- Improved electrochemical properties of LiMn2O4 with the Bi and La co-doping for lithium-ion batteries
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A series of LiBixLaxMn2-2xO4 (x = 0, 0.002, 0.005, 0.010, 0.020) samples were synthesized by solution combustion synthesis in combination with calcination. The phase structure and morphology of the products were characterized by X-ray diffraction, scanning electron microscopy, and transition electron microscopy. The results demonstrated that a single-phase LiMn2O4 spinel structure was obtained for the LiBixLaxMn2-2xO4 (x = 0, 0.002, 0.005) samples, whereas impurities were observed for the LiBixLaxMn2-2xO4 (x = 0.010, 0.020) samples as a result of the doping limit. The electrochemical properties were investigated by galvanostatic charge-discharge cycling and cycling voltammetry in a voltage range of 3.2-4.4 V. The substitution of Mn3+ by equimolar Bi3+ and La3+ could significantly improve the structural stability and suppress the Jahn-Teller distortion, thereby resulting in improved electrochemical properties for the Bi and La co-doped samples in contrast with the pristine LiMn2O4 sample. In particular, the LiBi0.005La0.005Mn1.99O4 sample delivered a high initial discharge capacity of 130.2 mA h g-1 at 1C, and following 80 cycles, the capacity retention was as high as 95.0%. Moreover, it also presented the best rate capability among all the samples, in which a high discharge capacity of 98.3 mA h g-1 was still maintained at a high rate of 7C compared with that of 75.8 mA h g-1 for the pristine LiMn2O4 sample.
- Han, Cheng-Gong,Zhu, Chunyu,Saito, Genki,Akiyama, Tomohiro
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- Synergistic Catalytic Effect of a Series of Energetic Coordination Compounds based on Tetrazole-1-acetic Acid on Thermal Decomposition of HMX
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A series of energetic coordination compounds [Co(tza)2}n (1), [Bi(tza)3]n (2), {[Cu4(tza)6(OH)2]·4H2O}n (3), [Mn(tza)2]n (4), {[Bi(tza)(C2O4)(H2O)]·H2O}n (5) and [Fe3O(tza)6(H2O)3]NO3 (6) based on tetrazole-1-acetic acid (Htza) were synthesized though environmentally friendly methods. The coordination compounds were characterized by elemental analyses, IR spectroscopy, single-crystal and powder X-ray diffraction (PXRD), thermogravimetric analyses (TG), and differential scanning calorimetry (DSC). Their catalytic performances and the synergetic catalytic effects between 1 and 2, 3 and 4, 5 and 6 on the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were all investigated by DSC. The results revealed that compounds 1–6 are thermally stable energetic compounds and they all exhibit high catalytic action for HMX thermal decomposition. The catalytic effects of the compounds on HMX thermal decomposition are closely related to the oxides, which come from the decomposition of the compounds, but have no positive relationships with the heat releases of the compounds themselves. Moreover, the synergetic catalytic effects between 1 and 2, 3 and 4, 5 and 6 were observed. Their mixtures at different mass ratio have different synergetic catalytic effects, and the sequence of the biggest synergetic index (SI) in each system is copper-manganese system (compounds 3 and 4) > iron-bismuth system (compounds 5 and 6) > cobalt-bismuth system (compounds 1 and 2), indicating that the synergistic catalytic effects are mainly related to the combination and the proportion of the compounds.
- Qu, Yuan-Yuan,Wei, Zhi-Xian,Kang, Li,Xie, Fei,Zhang, He-Dan,Yue, Pan
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- The preparation and characterization of composite bismuth tungsten oxide with enhanced visible light photocatalytic activity
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A composite photocatalyst (Bi3.84W0.16O 6.24-Bi2WO6) containing Bi, W and O elements was prepared by a facile hydrothermal method. Various characterization methods such as X-ray powder diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy and transmission electron microscopy were employed to investigate the structure and optical properties. The activities of the samples were evaluated by the photocatalytic degradation of methylene blue under visible light irradiation. The results showed that when the pH of the precursor solution is 12.3, and a hydrothermal treatment at 140 °C for 20 h was used, the prepared sample shows the mixed phases of Bi3.84W 0.16O6.24 and Bi2WO6. The Bi 3.84W0.16O6.24-Bi2WO6 composite exhibited an enhanced photocatalytic activity compared with single Bi2WO6 or Bi3.84W0.16O 6.24. The rate constant of Bi3.84W0.16O 6.24-Bi2WO6 is about 5 times that of Bi 2WO6. It is proposed that the increased photocatalytic activity may be attributed to the formation of a heterojunction between Bi 3.84W0.16O6.24 and Bi2WO 6, which suppresses the recombination of photoexcited electron-hole pairs.
- Chen, Shifu,Tang, Wenming,Hu, Yingfei,Fu, Xianliang
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- Reaction of bismuth nitrate with sodium citrate in water-glycerol solutions
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The reaction in a Bi(NO3)3-Na3Hcit-(H 2O + glycerol) system was studied in a wide range of component ratios by the solubility method and pH-metry in combination with chemical analysis of solid phases. Poorly sol
- Kuvshinova,Skorikov,Volodin
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- Mechanochemical destruction of decabromodiphenyl ether into visible light photocatalyst BiOBr
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In the present study, mechanochemical (MC) treatment of polybrominated diphenyl ethers (PBDEs), a kind of emerging persistent organic pollutant (POPs), was performed using a high energy ball mill. With Bi2O3 as co-milling reagent, deca-BDE was effectively destroyed and no hazardous intermediates or organic products were observed in the MC reaction. Meanwhile, BiOBr, a promising visible light photocatalyst, was proved to be the final product which could be utilized in further steps. Neither excessive Bi 2O3 nor unreacted deca-BDE was left after the reaction as they were originally added at stoichiometric ratio for BiOBr formation. FITR and Raman analyses demonstrate the collapse of deca-BDE skeleton and the cleavage of C-Br bonds with the generation of inorganic carbon, revealing the mechanism of carbonization and debromination. The gaseous products at different reaction atmosphere were also analyzed, showing that mostly CO2 with a fraction of CO were released during the MC process. The reaction formula of deca-BDE and Bi2O3 was then proposed based on the identified final products. Besides, the photocatalytic activity of the generated BiOBr was evaluated using methyl orange as the model pollutant. A good degradation performance from BiOBr was achieved under both simulated sunlight and visible light irradiation, indicating the possibility for its further utilization. This journal is the Partner Organisations 2014.
- Zhang, Kunlun,Huang, Jun,Wang, Haizhu,Yu, Gang,Wang, Bin,Deng, Shubo,Kano, Junya,Zhang, Qiwu
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- Secondary Phosphine Oxide Functionalized Gold Clusters and Their Application in Photoelectrocatalytic Hydrogenation Reactions
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Ligands in ligand-protected metal clusters play a crucial role, not only because of their interaction with the metal core, but also because of the functionality they provide to the cluster. Here, we report the utilization of secondary phosphine oxide (SPO), as a new family of functional ligands, for the preparation of an undecagold cluster Au11-SPO. Different from the commonly used phosphine ligand (i.e., triphenylphosphine, TPP), the SPOs inAu11-SPOwork as electron-withdrawing anionic ligands. While coordinating to gold via the phosphorus atom, the SPO ligand keeps its O atom available to act as a nucleophile. Upon photoexcitation, the clusters are found to inject holes into p-type semiconductors (here, bismuth oxide is used as a model), sensitizing the p-type semiconductor in a different way compared to the photosensitization of a n-type semiconductor. Furthermore, theAu11-SPO/Bi2O3photocathode exhibits a much higher activity toward the hydrogenation of benzaldehyde than a TPP-protected Au11-sensitized Bi2O3photocathode. Control experiments and density functional theory studies point to the crucial role of the cooperation between gold and the SPO ligands on the selectivity toward the hydrogenation of the C═O group in benzaldehyde.
- Wang, Yu,Liu, Xiao-He,Wang, Rongbin,Cula, Beatrice,Chen, Zhe-Ning,Chen, Qingyun,Koch, Norbert,Pinna, Nicola
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- TiO2-Bi2O3/(BiO)2CO3-reduced graphene oxide composite as an effective visible light photocatalyst for degradation of aqueous bisphenol A solutions
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TiO2 nanorods (T) were combined with a narrow band gap semiconductor β-Bi2O3 (B) to form a heterojunction, which makes it possible for TiO2 to become active as a photocatalyst also under visible light illumination. To further increase the photocatalytic activity of TiO2 + Bi2O3/(BiO)2CO3 (TB) composite, we used a hydrothermal procedure to link it with reduced graphene oxide (rGO). Structural, surface and electronic properties of the obtained catalysts were analyzed and correlated to their performance in photocatalytic oxidation of aqueous bisphenol A (BPA) solution conducted in a batch reactor under visible light illumination. XRD, FTIR, UV–vis DR spectroscopy and photocurrent measurements of visible light illuminated TB composite catalyst clearly showed that (i) β-Bi2O3 acts as a photosensitizer for TiO2 and (BiO)2CO3 present in the TB composite, (ii) holes (h+) are photo-generated in valence band (VB) of β-Bi2O3 and due to the β-Bi2O3/TiO2 heterojunction transferred into VB of TiO2, (iii) p-n junction between β-Bi2O3 and TiO2 allows the photo-generated electrons (e?) in the conduction band (CB) of β-Bi2O3 to transfer to TiO2, and (iv) p-n junction between β-Bi2O3 and (BiO)2CO3 allows the photo-generated electrons in the conduction band of β-Bi2O3 to transfer to (BiO)2CO3. This means that more charge carriers are available to participate in the catalytic visible-light triggered oxidation process for the degradation of organic pollutants dissolved in water. The highest photocurrent density was measured for multi-phase TBR (TB + rGO) composite, which indicates that visible-light generated charge carriers in TB composite are injected into the reduced graphene oxide. The latter acts as a web for charge carrier percolation and suppresses the recombination of electron-hole pairs, thus resulting in improved catalytic activity of TBR. The results of UV–vis DR spectroscopy and photocurrent density measurements were entirely in line with the results of photocatalytic oxidation of water dissolved bisphenol A (BPA) in batch reactor under visible light illumination.
- ?erjav, Gregor,Djinovi?, Petar,Pintar, Albin
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- Synthesis and study of ammonium hexamolybdobismuthate(III)
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Ammonium hexamolybdobismuthate(III) of composition (NH4) 3[BiMo6O18(OH)6] · 7H 2O (I) was synthesized and studied by mass spectrometry, X-ray diffraction, IR spectroscopy, and thermogravimetry. The compound is monoclinic: a = 10.438 A?, b = 7.909 A?, c = 18.127 A?, β = 96.59°, V = 1486.76 A?3, ρcalc = 3.32 g/cm3, Z = 2. Pleiades Publishing, Ltd., 2011.
- Oreshkina,Kaziev,Lobanov,Steblevskii
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- Characterization and photocatalytic activity of Bi3TaO7 prepared by hydrothermal method
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In this paper, Bi3TaO7 nanoparticles with visible light response have been prepared via a facile hydrothermal route and solid-state reaction. The photocatalytic performance of as-prepared samples was evaluated by the degradation of Tetracycline hydrochloride (TC). It was observed that the sample obtained by hydrothermal method showed an enhanced photocatalytic activity in contrast to the sample prepared by solid-state method. This could be ascribed to the efficient separation of photogenerated electrons and holes in the sample prepared via hydrothermal process, which is certified by the photoluminescence spectroscopy (PL) and transient photocurrent analysis. Moreover, the result of nitrogen adsorption-desorption isotherm indicated the existence of mesoporous structure in as-prepared sample with hydrothermal process, and specific surface area is significantly higher than the sample obtained by solid-state method. The optimal conditions involved in the photocatalytic reaction, such as TC concentration, catalyst concentration and pH value were investigated.
- Luo, Bifu,Chen, Min,Zhang, Zhengyuan,Hong, Yuanzhi,Lv, Taotao,Shi, Weidong
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- FORMATION OF HIGH OXIDE ION CONDUCTIVE PHASES IN THE SINTERED OXIDES OF THE SYSTEM Bi2O3-Ln2O3 (Ln equals La-Yb).
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The electrical conduction in various phases of the system Bi//2O//3-Ln//2O//3 (Ln equals La, Nd, Sm, Dy, Er, or Yb) was investigated by measuring ac conductivity and the emf of the oxygen gas concentration cell. High-oxide-ion conduction was observed in the rhombohedral and face-centered cubic (fcc) phase in these systems. The fcc phase could be stabilized over a wide range of temperature by adding a certain amount of Ln//2O//3. In these cases, the larger the atomic number of Ln, the lower the content of Ln//2O//3 required to form the fcc solid solution, except in the case of Yb//2O//3. The oxide ion conductivity of this phase decreased with increasing content of Ln//2O//3.
- Iwahara,Esaka,Sato,Takahashi
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- Organic–inorganic hybrid [H2mdap][BiCl5] showing an above-room-temperature ferroelectric transition with combined order–disorder and displacive origins
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Recently, molecule-based ferroelectric materials have drawn much attention due to their potential multifunctional optoelectronic device applications such as sensors, actuators, optical and memory devices. Therefore, the design of molecular ferroelectrics, explore their ferroelectrics origins and high performance are of significance. In this work, an organic–inorganic hybrid compound [H2mdap][BiCl5] (mdap?=?N-methyl-1,3-diaminopropane; 1) is found to exhibit brilliant ferroelectricity below 372?K. Ferro-paraelectric transition origins the order–disorder of the organic cations and relative displacements of the cis-connected ions in the anionic chains in the crystal lattice via the structural analysis. Second harmonic generation and ferroelectric hysteresis loop measurements reveal typical polarization switching with a spontaneous polarization of 2.38?μC?cm?2 at 353?K.
- Wang, Ya,Shi, Chao,Han, Xiang-Bin
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- A 3-D bismuth-organic framework containing 1-D cationic inorganic [Bi2O2]2+ chains
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A three-dimensional Bi(III) based metal-organic framework was synthesized under hydrothermal conditions using the multidentate organic linker 3,5-pyridinedicarboxylate. Bismuth oxide 3,5-pyridinedicarboxylate, Bi2O2[NC5Hs
- Tran, Dat T.,Chu, Deryn,Oliver, Allen G.,Oliver, Scott R.J.
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- Enhanced luminescence and photocatalytic activity of Bi2O3:Ho3+ needles
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A series of Bi2O3:Ho3+ (0.2–5 mol% Ho) phosphors with a crystalline monoclinic phase was synthesized using a co-precipitation route. The particle morphology and size were determined using a field emission scanning electron microscope (FESEM). The FESEM showed that the synthesized material consisted of needle-like particles. The oxidation state of the Bi as well as oxygen vacancies were investigated using X-ray photoelectron spectroscopy. It was found that Bi3+ was the dominant oxidation state in the samples, although Bi2+ was also detected. The doped Bi2O3 revealed a decrease in bandgap with an increase in Ho3+ concentration. The photoluminescence (PL) revealed that Ho3+ was the emitting centre in the samples. The 5F4/5S2→5I8 transition was responsible for the most intense emission in the visible region, whereas the near infrared emissions resulted from the 5S2→5I6, 5I6→5I8 and 5S2→5I5 transitions. A superior catalytic activity and a high PL intensity were observed due to the presence of a higher number of oxygen vacancies and defects. The 4 mol% Ho3+ doped sample was found to have the optimum doping concentration for both the PL intensity and photocatalysis activity. The results revealed that Bi2O3:Ho3+ can be potentially used for solid state displays as well as a photocatalyst under UV–visible light exposure.
- Divya,Shivaramu,Coetsee,Kroon,Purcell,Swart
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- Controlled synthesis of a Bi2O3-CuO catalyst for selective electrochemical reduction of CO2 to formate
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The electro-reduction of CO2 to produce energy sources has been considered as a visionary pathway with the help of renewable electricity, which can achieve carbon neutrality and mitigate global warming. Nevertheless, developing a high selectivity, good activity and superior stability catalyst is a big challenge. Here, Bi2O3-CuO(x) bimetallic oxide catalysts were synthesized by a facile coordination-precipitation method with concisely controlled atomic ratios (Cu/Bi). They exhibit a remarkable performance for sufficient reduction of CO2 to formate, achieving a maximum faradaic efficiency of 89.3% at a potential of ?1.4 V vs. SCE. The catalysts are shown to be robust during 10 h of uninterrupted electrolysis. The notable catalytic activity suggests that controlling the Cu/Bi molar ratio is a key factor in developing special micro-structure Bi2O3-CuO(x) catalysts for electrochemical reduction of CO2 to formate in aqueous systems.
- Dai, Chaoneng,Qiu, Yue,He, Yu,Zhang, Qiang,Liu, Renlong,Du, Jun,Tao, Changyuan
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- Fabrication of La-Doped Bi2O3 Nanoparticles with Oxygen Vacancies for Improving Photocatalytic Activity
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Abstract: La-doped Bi2O3 were prepared via a simple sol–gel method following a facile low temperature calcination process, and citric acid as an organic complexing agent. La3+ doping could not only create oxygen vacanices (OVs) on the surface of Bi2O3, but also as the efficient scavenger to capture photogenerated electrons. The novel x% La–Bi2O3 photocatalysts exhibited oxidation capacities for degrading azo dye methyl orange (MO) and colorless pollutant phenol, and 2% La–Bi2O3 sample showed the highest photocatalytic activity. The enhanced photocatalytic activity in MO and phenol photo-degradation were attributed to the strong synergistic effects of La3+-doping and oxygen vacancies (OVs), which La3+ ions capture, transfer, and release the photo-generated electrons for conversion from O2 to ·O2- to prevent the hot e? of CB to jump into the level of OVs, thereby increase separation efficiencies of photo-generated electrons and holes. The present study may present a new perspective for the utilization of rare earth ion doping to improve the performance of other photocatalytic materials. Graphic Abstract: [Figure not available: see fulltext.].
- Li, Ting,Quan, Shanyu,Shi, Xuefeng,Yang, Linmei,Liu, Cong
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- Photo-and thermogeneration of singlet oxygen by the metal ions deposited on Al2O3 and SiO2
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The specifics of photo-and thermogeneration of singlet molecular oxygen by metal oxides deposited on silica gel and Al2O3 were studied. The deposited oxides were observed to generate equilibrium and superequilibrium concentrations of 1ΔgO2. The V2O5/SiO2 and MoO3/SiO 2 systems were found to be most active in both types of generation. A common mechanism of photo-and thermogeneration was proposed. Pleiades Publishing, Inc., 2006.
- Shcherbakov,Emel'yanov,Khaula,Il'ichev,Vishnetskaya,Rufov
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- Infrared, Raman, 1H NMR, thermal and positron annihilation lifetime studies of Pb(II), Sn(II), Sb(III), Bi(III)-barbital complexes
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Metal complexes of Pb(II), Sn(II), Sb(III) and Bi(III) with a barbital sodium were synthesized and characterized by several techniques, including elemental analysis (C, H and N), molar conductance measurements, infrared, Raman, 1H NMR, positron annihilation lifetime and thermogravimetric analysis. Reactions of barbital sodium (NaL) with salts of Pb(NO 3)2, SnCl2?2H2O, SbCl 3 and BiCl3 affords four novel mononuclear complexes [Pb(HL)2], [Sn(L)(H2O)], [Sb(HL)(L)] and [Bi(HL)(L)]. In complexes of Pb(II), Sb(III) and Bi(III), the molar ratio of metal-to-ligand is 1:2. Both of Sb(III) and Bi(III) complexes have six coordination via two molecules of barbital (HL and L), one of them deprotonated NH. The Pb(II) complex has a central metal ion adopts tetradentate fashion which surrounded by two (HL) barbital moieties. The elemental analysis shows that Sn(II) complex is tetradentate 1:1 ratio, chelated through oxygen O of (ONa), deprotonated (NH) and one coordinated water molecule. The positron annihilation lifetime parameters were found to be dependent on the structure, electronic configuration and molecular weight of metal complexes.
- Refat, Moamen S.,Sharshar
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- Electrochemical synthesis of single-crystal (Ba0.05K0.95)BiO3·1/6H2O with the KSbO3 structure
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A new compound with a cubic structure, (Ba0.05K0.95)BiO3·1/6H2O (BKBO), was synthesized by electrochemical crystal growth using a rotating anode in molten KOH flux at 255 °C. The BKBO crystal had the KSbO3 structure and belonged to space group Im3 (No. 204) with Z = 12. Refinement of X-ray diffraction data at room temperature gave a = 10.0204(2) angstroms, V = 1006.1(1) angstroms3, and R = 2.4% for 1465 unique reflections. Potassium, barium, and hydrated oxygen were found to occupy different sites in the tunnel structure. The electrical conductivity at room temperature was similar to the ionic conductor KBiO3. BKBO decomposed to Bi2O3, K2O, and BaO above 400 °C.
- Jung,Han,Wilson,Payne
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- Alkali-treatment synthesis of bismuth vanadium oxide photocatalysts with different morphologies
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The bismuth vanadium oxide photocatalysts with different phases and morphologies were facilely synthesized by the alkali-treatment synthesis method. BiVO4 polyhedrons as the raw materials were firstly prepared by a facile hydrothermal method. With the change of the concentrations of NaOH, the surfaces of the raw BiVO4 polyhedrons became rough and then other phases appeared, such as Bi2O3 regular tetrahedrons, Bi7VO13 sheets and rods, and Bi25VO40 triangle-blocks and cuboids. When the concentration of NaOH was 0.1 ?M, the obtained samples were the composites of the polyhedral BiVO4 and regular tetrahedral Bi2O3, which exhibited the best photocatalytic activity in the degradation of several organic pollutants. From the exploration of the degradation mechanism, it showed that the transfer rate of photogenerated electron–hole pairs on the composites of BiVO4 and Bi2O3 was promoted. The h+, ?OH and O2?- played key effect in the degradation process. Furthermore, the bismuth vanadium oxide photocatalysts also showed antibacterial activities towards E. coli.
- Feng, Yuanyuan,Jing, Zhihong,Kong, Defen,Kong, Desheng,Li, Wenjuan,Shi, Meng,Yan, Tingjiang,You, Jinmao
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- Photocatalyst Bi(OH)SO4 · H2O with High Photocatalytic Performance
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Abstract: In this work, Bi(OH)SO4 · H2O, a novel photocatalyst was prepared by a facile method. The sample was characterized by XRD, XPS, SEM, Mott-Schottky curve and ESR. The band gap of Bi(OH)SO4 · H2O is about 4.64 eV, and its CB and VB are estimated at –0.5 and 4.14 eV, respectively. Degradation of RhB and PhOH under UV light irradiation illustrates that the sample has good UV activity. The results of ESR spectra and tapping experiments indicate that the main active species in the photocatalytic reaction process are hydroxyl radicals, superoxide radicals and holes. A possible mechanism of catalytic degradation of organic pollutants was proposed. This semiconductor has a positive valence band and high oxidation capacity theoretically and it may have broad application in synthesizing highly efficient photocatalysts through doping other elements or creating heterojunctions.
- Haojie Lu,Wang, Ruiting,Zhang, Linghua,Chen, Daimei,Hao, Qiang,Ma, Chao,Yao, Wenqing
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- BiVO4/Bi2O3 submicrometer sphere composite: Microstructure and photocatalytic activity under visible-light irradiation
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Bismuth vanadate (BiVO4) powders were synthesized by homogeneous precipitation method with different surface dispersants. Bi(NO3)3·5H2O and NH4VO3 were utilized as starting materials to syn
- Li, Lingzhi,Yan, Bing
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- Three novel bismuth-based coordination polymers: Synthesis, structure and luminescent properties
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Three novel bismuth-based coordination polymers, [(CH3)2NH2][Bi(pdc)(bdc)]·2DMF, [(CH3)2NH2][Bi(tdc)2]·1.5DMF and [Bi(bpdc)2H2O]·xGuest (compounds 1–3) (H2pdc = 3,5-pyridinedicarboxylic acid, H2bdc = 1,4-benzenedicarboxylic acid, H2tdc = 2,5-thiophenedicarboxylic acid, H2bpdc = 4,4′-biphenyldicarboxylic acid), have been successfully synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction. Compounds 1 and 2, which are constructed by 9-coordinated or 8-coordinated Bi3 +, feature three-dimensional structures with hms and dia topology, respectively. However, 5-coordinated Bi3 + based compound 3 is a two-dimensional layered structure. Compound 1 can tune emissive performance by doping different lanthanide ions Tb3 +, Eu3 + and Dy3 +. Furthermore, detection of nitro explosives is investigated. All of the compounds are characterized by elemental analysis, IR spectrum and thermogravimetric analysis.
- Kan, Liang,Li, Jiantang,Luo, Xiaolong,Li, Guanghua,Liu, Yunling
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- Synthesis and characterization of nanosized SrBi2Ta2O9 powder by a novel sol-gel process
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Chemically homogeneous SrBi2Ta2O9 (SBT) sol was synthesized using ethoxy tantalum, strontium acetate, and bismuth subnitrate as starting materials, methoxyethylene as a solvent and acetic acid (HOAc) as a catalyst. Single-phased perovskite phase SBT ferroelectric ultrafine powder was obtained after the dried gel was treated at 350°C for 30min and calcined at 800°C for 1h. FT-IR, XRD, TEM and TG-DTA were employed to investigate the transformation processes of sol to gel and gel to ultrafine SBT powder. Acetic acid not only acts as an acid catalyst, but also changes the alkoxide precursor as a ligand at a molecular level. Bidentate acetates replace OR groups and are directly bounded to the tantalum, leading to the formation of Ta (OR)x(OAc)5-x. The perovskite SBT phase formed via intermediate phase Bi3TaO7 and a Bi-deficient pyrocholore phase.
- Wang, Wen,Jia, Dechang,Zhou, Yu,Ye, Feng
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- A new method of synthesis of BiFeO3 prepared by thermal decomposition of Bi[Fe(CN)6]?4H2O
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In order to investigate the formation of the multiferroic BiFeO 3, the thermal decomposition of the inorganic complex Bismuth hexacyanoferrate (III) tetrahydrate, Bi[Fe(CN)6]?4H2O has been studied. The starting material and the decomposition products were characterized by IR spectroscopy, thermal analysis, laboratory powder X-ray diffraction, and microscopic electron scanning. The crystal structures of these compounds were refined by Rietveld analysis. BiFeO3 were synthesized by the decomposition thermal method at temperature as low as 600 °C. There is a clear dependence of the type and amount of impurities that are present in the samples with the time and temperature of preparation.
- Navarro,Lagarrigue,De Paoli,Carbonio,Gomez
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- Enhancing the thermoelectric power factor of nanostructured ZnCo2O4by Bi substitution
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BixZnCo2-xO4(0 =x= 0.2) nanoparticles with differentxvalues have been prepared by the sol-gel method; the structural, morphological, thermal and thermoelectric properties of the prepared nanomaterials are investigated. XRD analysis confirms that Bi is completely dissolved in the ZnCo2O4lattice till thexvalues of =0.1 and the secondary phase of Bi2O3is formed at higherxvalue (x> 0.1). The synthesized nanomaterials are densified and the thermoelectric properties are studied as a function of temperature. The electrical resistivity of the BixZnCo2-xO4decreased withxvalue and it fell to 4 × 10-2O m for the sample withxvalue = 0.1. The Seebeck coefficient value increased with the increase of Bi substitution till thexvalue of 0.1 and decreased for the sample with higher Bi content (x= 0.2) as the resistivity of the sample increased due to secondary phase formation. With the optimum Seebeck coefficient and electrical resistivity, Bi0.1ZnCo1.9O4shows the high-power factor (a2s550 K) of 2.3 μW K-2m-1and figure of merit of 9.5 × 10-4at 668 K respectively, compared with other samples. The experimental results reveal that Bi substitution at the Co site is a promising approach to improve the thermoelectric properties of ZnCo2O4.
- Alagar Nedunchezhian, A. S.,Anbalagan, G.,Arivanandhan, M.,Fujiwara, K.,Jayavel, R.,Maeda, K.,Rajkumar, R.,Sidharth, D.,Yalini Devi, N.
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- Electrochemistry of powder material studied by means of the cavity microelectrode (CME)
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The kinetic aspects of powder material electrochemistry can be studied using the cavity microelectrode (CME) as it allows carrying out voltammetry at scan rates between a few millivolts per second to several hundreds of volts per second. Thus, significant voltammogram characteristics-scan rate profiles can be drawn. Theoretical models suited to each material needs to be developed for their exploitation. First, we report significant results obtained with CME on powder materials. The materials studied were chosen for their wide variety of possible applications such as battery materials (polyaniline or Bi2O3, which modifies the electrochemical behavior of materials in which it is included), supercapacitor (carbon black), and for the electrocatalytic hydrogenation of organic compounds (PtO2). Secondly, we briefly describe the general action for establishing models to obtain a better understanding of the electrochemical processes.
- Cachet-Viviera,Vivier,Cha,Nedelec,Yu
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- Template Synthesis and Characterization of Bi 2O 3-Based Composite Nanoclusters Within Diblock Copolymer
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Diblock copolymer templates were synthesized using norbornene and 5-norbornene-2, 3-dicarboxylic acid by ring-opening metathesis polymerization. By introducing bismuth salt into these prepared diblock copolymer template, the Bi2O3-based composite nanoclusters were achieved. XRD, FTIR, and TEM were used severally to characterize the Bi2O3 particles, the process of oxide formation, and the size of nanoclusters.
- Pan, Chuanyi,Li, Xuehui,Wang, Lefu
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- Combined photocatalytic degradation of pollutants and inactivation of waterborne pathogens using solar light active α/β-Bi2O3
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A solar light active composite of α/β-Bi2O3 was synthesized using a chemical-free solid-state reduction method. The obtained composite was characterized by X-ray diffraction, UV–vis spectroscopy, field emission scanning electron microscopy, and zeta potential. Initially, to validate the photocatalytic effectiveness, the obtained α/β-Bi2O3 composite was used to degrade indigo carmine dye. Then, the inactivation of E. coli and S. aureus waterborne pathogens was performed on solid and in liquid media. On solid agar media, a significant inhibition zone was observed for both bacterial strains. Similarly, in liquid culture, these strains E. coli and S. aureus were reduced from 1 × 106 CFU/mL to a few CFU/mL, after 240 min of photocatalytic exposure. Furthermore, mixed wastewater of indigo carmine and E. coli/S. aureus were tested to study the combined photocatalytic mechanism against the organic dye and microorganisms. Overall, the obtained results suggested the efficacy of α/β-Bi2O3 towards visible light inactivation of bacteria even in combination with other pollutants, highlighting the great potential of the advanced photocatalytic process for combined treatment of organic pollutants and pathogens.
- Channa, Najeebullah,Gadhi, Tanveer A.,Mahar, Rasool Bux,Chiadò, Alessandro,Bonelli, Barbara,Tagliaferro, Alberto
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- Novel perovskite nanocatalyst (BiFeO3) for the photodegradation of rhodamine B/tartrazine and swift reduction of nitro compounds
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Design and synthesis of visible light respondent photocatalyst with high separation efficiency is of great importance due to its application in practical point of view. In this presentation, novel perovskite-structured BiFeO3 nanoparticles have been successfully synthesized by simple, cost-effective and eco-friendly technique. The BiFeO3 nanoparticles were prepared by using different chelating agents (sucrose, citric acid, tartaric acid and urea) and under different range of calcination temperature (150–850?°C). Different characterization techniques such as FT-IR, XRD, VSM, BET, TEM and UV–Vis spectroscopy have been used for its structure evaluation. Further, by using this catalyst, a green approach has been developed for the removal of harmful organic compounds from the industrial waste. The catalytic activity was assessed by the catalytic degradation of industrial waste dyes such as rhodamine B and tartrazine (first time by perovskite-structured material) in aqueous media under sunlight irradiation and reduction of various nitro compounds to corresponding amines (in s) by using NaBH4 in green solvent water at room temperature. Effect of all types of BiFeO3 nanoparticles on catalytic degradation and reduction was investigated. BiFeO3 nanoparticles prepared by sucrose as chelating agent and calcinated at 650° were selected as a better catalyst on the basis of its performance in degradation and reduction experiment. Thus, the present approach provides a promising way to prepare noble catalyst for extensive applications in degradation/reduction of organic pollutants. The examination of degraded products of dye has been carried out by using FT-IR; mass spectroscopy and UV–Vis spectroscopy and confirmation of reduction of nitrocompounds with UV–Vis spectroscopy.
- Singh, Harminder,Rajput, Jaspreet Kaur
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- Automated diffraction tomography for the structure elucidation of twinned, sub-micrometer crystals of a highly porous, catalytically active bismuth metal-organic framework
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A combined approach: A permanent highly porous bismuth-containing metal-organic framework (CAU-7) has been synthesized and its structure determined by a combination of electron diffraction, Rietveld refinement, and DFT calculations. The compound is catalytically active in the hydroxymethylation of furan (see picture). Copyright
- Feyand, Mark,Reimer, Tim,Stock, Norbert,Mugnaioli, Enrico,Kolb, Ute,Dieterich, Johannes M.,Vermoortele, Frederik,Bueken, Bart,De Vos, Dirk
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p. 10373 - 10376,4
(2012)
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- One-step hydrothermal formation of Bi2O3 nanourchins with radially ultrathin nanotubes
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A novel Bi2O3 urchin-like microarchitecture with high-density radially oriented Bi2O3 nanotubes (NTs) was fabricated by a one-step hydrothermal approach without any template or surfactant at a relative low temperature of 90 °C. The radial Bi 2O3 NTs on the surface of nanourchins (NUs) were 4-7nm in diameter and ~ 1.7 μm in length. The mean wall thickness of the NTs was as thin as 1.5 nm. Based on the time-dependent evolutions of morphology examined by scanning electron microscope (SEM), a rolling-up mechanism was demonstrated to explain the formation of the ultrathin Bi2O 3 NTs. The ultrathin and long NTs bring on the high surface-to-volume ratios of the Bi2O3 urchin-like microarchitectures, which makes them great potential applications in gas sensors, photocatalysis, environmental purification, and solar energy conversion.
- Lu, Hongbing,Wang, Shimin,Dong, Binghai,Xu, Zuxun,Zhao, Li,Li, Jinchai
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- Precipitation of bismuth(III) oxobromide from bromide media
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Abstract-X-ray phase analysis, thermogravimetry, IR spectroscopy, and chemical analysis were used to study bismuth(III) precipitation from nitrate solutions upon addition of aqueous solutions of hydrobromic acid or ammonium bromide, and from bismuth-containing hydrobromic acid solutions. The conditions in which bismuth(III) oxobromide of BiOBr composition is formed were determined and the possibility of obtaining a high-purity product was assessed.
- Novokreshchenova,Daminova,Yukhin
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- Low-temperature vacuum reduction of BiMnO3
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Low-temperature vacuum reduction was used for the preparation of the oxygen-deficient BiMnO2.81 sample in a bulk form from stoichiometric BiMnO3. The transformation occurs in vacuum better than 10 -3 Pa at a narrow temperature range of 570-600 K. The structure of the new phase was analyzed using synchrotron X-ray powder diffraction data. BiMnO2.81 crystallizes in a perovskite-type cubic structure (space group I-43d) with a = 15.88552(5) A corresponding to a 4ap superstructure, where ap is the parameter of the cubic perovskite subcell. Oxygen vacancies are ordered, and one oxygen site in BiMnO 2.81 is completely vacant, resulting in MnO5 pyramids. BiMnO2.81 is rather unstable in air and slowly restores its oxygen content even at room temperature.
- Belik, Alexei A.,Matsushita, Yoshitaka,Tanaka, Masahiko,Takayama-Muromachi, Eiji
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- Direct Z-scheme Cs2O-Bi2O3-ZnO heterostructures for photocatalytic overall water splitting
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In this work, a direct Z-scheme Cs2O-Bi2O3-ZnO heterostructure without any electron mediator is fabricated by a simple solution combustion route. Cs2O is chosen as a sensitizer to expand the light absorption range, and in addition, its conduction band minimum (CBM) and valence band maximum (VBM) positions are suitable to construct a direct Z-scheme system with ZnO and Bi2O3. Structural and elemental analyses show clear evidence for heterostructure formation. The Z-scheme charge carrier migration pathway in Cs2O-Bi2O3-ZnO is confirmed by high resolution XPS and ESR studies. The fabricated heterostructure exhibits a good ability to split water to H2 and O2 under simulated sunlight irradiation without any sacrificial agents or co-catalysts and has excellent photostability. The apparent quantum efficiency of the optimized Cs2O-Bi2O3-ZnO heterostructure reaches up to 0.92% at 420 nm. The excellent efficiency of this fabricated heterostructure is attributed to the efficient charge carrier separation, the high redox potential of the CBM and VBM benefiting from a direct Z-scheme charge carrier migration pathway and the extended light absorption range.
- Hezam, Abdo,Namratha,Drmosh,Ponnamma, Deepalekshmi,Nagi Saeed, Adel Morshed,Ganesh,Neppolian,Byrappa
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- Optical properties of bismuth oxide thin films prepared by reactive d.c. magnetron sputtering onto p-GaSe (Cu)
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Bismuth oxide (Bi2O3) thin films with thickness in the range 20-160 nm have been deposited by d.c. reactive magnetron sputtering of Bi in an atmosphere Ar:O2 (1:1), onto single crystalline p-GaSe (Cu) substrates. The optic
- Leontie, Liviu,Caraman,Evtodiev, Igor,Cuculescu, Elmira,Mija, Ana
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- Synthesis and structure of pentavalent bismuth(V) alkoxides and ligand redistribution equilibria in solution
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The six new pentavalent Bi(V) alkoxide complexes Ph3Bi(OR)2, 1, Ph3BiBr(OR), 2, and Ph4Bi(OR), 3 (a, R = C6F5; b R = C6Cl5) have been prepared. Ph4Bi(OR) was synthesized by alcoholysis of BiPh5 with ROH. Ph3Bi(OR)2 and Ph3BiBr(OR) were products of the salt elimination reaction between Ph3BiBr2 and NaOR. These compounds were characterized spectroscopically and by single-crystal X-ray diffraction. In the solid state, they possess distorted trigonal bipyramidal coordination geometries. Although the mixed species Ph3BiBr(OR) may be isolated in pure form as crystalline solids, they do not exist as pure compounds in solution owing to the very rapid redistribution equilibrium Ph3Bi(OR)2 + Ph3BiBr2 ? 2Ph3BiBr(OR). The equilibrium constants were measured using VT NMR spec-troscopy. For comparison, the equilibrium constants for the previously unreported cross-exchange reactions between the dihalides Ph3BiX2 (X = F, Cl, Br) were also measured at 226 K. Trends observed in the values of Keq correlate with the difference in the electro-negativity of the mixed X species. The thermal stabilities of Ph3Bi(OR)2 were examined in toluene solution and in the solid state. Pyrolysis results in elimination of ROPh for both R = C6F5 and C6Cl5.
- Hoppe, Silke,Whitmire, Kenton H.
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- Bi2O3 and g-C3N4 quantum dot modified anatase TiO2 heterojunction system for degradation of dyes under sunlight irradiation
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A facile and feasible method was successfully utilized to incorporate Bi2O3 and g-C3N4 quantum dots on TiO2 surface to synthesize a novel composite g-C3N4/TiO2/Bi2O3. The photocatalytic activity of the composite g-C3N4/TiO2/Bi2O3 for degradation of dyes under sunlight and UV light irradiation was evaluated. It possessed the higher photocatalytic performance than that of pristine TiO2 or g-C3N4 under the same conditions. Under sunlight irradiation, the reaction rate constants of the g-C3N4/TiO2/Bi2O3 was about 4.2 times and 3.3 times higher than that of TiO2 and g-C3N4, respectively. The promising photocatalytic performance was attributed to the broader light absorption range and efficient separation of photoinduced carriers. Moreover, based on the TEM, XPS, XRD, UV-vis spectrum, radicals scavenging test and Mott-Schottky analysis systematic mechanism for photodegradation process was proposed. This work provides a promising strategy for the modification of TiO2-based semiconductors by incorporating different quantum dots and promoting the efficiency of the photocatalysts in practical application.
- Peng, Weidong,Yang, Chun,Yu, Jiang
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- Molecular Design for Tailoring a Single-Source Precursor for Bismuth Ferrite
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Nearly phase-pure bismuth ferrite particles were formed by thermolysis of the single-source precursor [Cp(CO)2FeBi(OAc)2] (1) in octadecene at 245 °C, followed by subsequent calcination at 600 °C for 3 h. In contrast, the slightly modified compound [Cp(CO)2FeBi(O2CtBu)2] (2) yielded only mixtures of different bismuth oxide phases, revealing the distinctive influence of molecular design in material synthesis. The chemical composition, morphology, and crystallinity of the resulting materials were investigated by X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the optical properties were investigated by Fourier transform infrared and UV-vis spectroscopies, showing a strong band gap absorption in the visible range at 590 nm (2.2 eV). The magnetic behavior was probed by vibrating-sample and superconducting quantum interference device magnetometry, as well as 57Fe M?ssbauer spectroscopy.
- Bendt, Georg,Schiwon, Rafael,Salamon, Soma,Landers, Joachim,Hagemann, Ulrich,Limberg, Christian,Wende, Heiko,Schulz, Stephan
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- Development of BiOI as an effective photocatalyst for oxygen evolution reaction under simulated solar irradiation
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In this study, crystalline BiOI powders were prepared for photocatalytic O2evolution in the presence of NaIO3as the electron mediator. BiOI with a microspherical morphology, a layered structure composed of [Bi2O2]2+and intercalated I?ions, exhibited a suitable valence band level to generate photoexcited holes for O2evolution. Moreover, ruthenium was loaded using the impregnation or photodeposition method to produce RuO2as a co-catalyst to improve the photocatalytic activity of BiOI. Photodeposited RuO2-loaded BiOI showed a high O2evolution rate of 2730 μmol h?1and can be reused eight times in the presence of NaIO3under simulated solar irradiation. The high photocatalytic O2evolution can be attributed to the highly dispersed RuO2, which could serve as an effective electron sink, on the surface of BiOI and its enhanced visible light-harvesting ability. Besides, the presence of NaIO3in the system was effective to receive photoexcited electrons from RuO2-loaded BiOI for improving charge separation and hence the O2evolution from RuO2sites on the BiOI surface. The RuO2-loaded BiOI with high photocatalytic activity and stability for generating O2could be a potential candidate for achieving overall water splitting in aZ-scheme system in the presence of NaIO3for solar utilization in the future.
- Chen, Tzu-Hsin,Hu, Chechia,Lin, Kun-Yi Andrew,Tsunekawa, Shun,Wu, Jia-Hao,Yoshida, Masaaki
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- Bimetallic Salen-Based Compounds and Their Potential Applications
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The new bimetallic coordination compounds [LNiAg(NO3)], [LCuMn(NO3)2], [LCuCu(NO3)2], [LCuZn(NO3)2], and [{LCuBi(NO3)3}(ACN)] have been synthesized from a salen-type ligand L containing two distinct coordination sites to accommodate (different) metal ions M1 and M2. In the solid state, the formation of 1:1 compounds (LCu:M2) is always observed, but interactions between the compounds lead to differences in packing. For example, a head-to-tail arrangement along the crystallographic b-axis is observed in the case of the LCuBi compound, and the LNiAg compound is polymeric, while its Cu homologue LCuAg forms a discrete dimer. Given the inherent potential of the preorganizing, two metal ions using L could be used to synthesize nanoscale copper-bismuth and-manganese mixed metal oxides as a function of the temperature. The combination of different bioactive metal ions within one ligand system was furthermore explored for antimicrobial efficiency.
- Abram, Sarah-Luise,Crochet, Aurélien,Finelli, Alba,Fromm, Katharina M.,Hérault, Nelly
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- Formation of Nd1–xBixFeO3 Nanocrystals under Conditions of Glycine-Nitrate Synthesis
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Nd1–xBixFeO3 nanocrystals with crystallite size 30?60 nm have been prepared under conditions of glycine–nitrate burning. Single-phase Nd1–xBixFeO3 nanocrystals are formed over the entire studied concentrations range if the glycine–nitrate synthesis is performed in excess of the oxidizer. Under these conditions, a continuous range of the Nd1–xBixFeO3 solid solutions (0 ≤ х ≤ 0.75) crystallized in the rhombic system (space group Pbnm) are formed without crystallization of the burning intermediates. The Nd1–xBixFeO3 solid solutions (х = 0.775, 0.8) crystallize in the rhombic system (space group Pbаm).
- Karpov,Tomkovich,Tugova
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- Bismuth and mixed bismuth-lanthanide carboxylates as precursors for pureand Ln-promoted bismuth molybdate catalysts
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Several bismuth(III) carboxylates (formate, acetate, propionate, oxalate, lactate) and the analogous tervalent lanthanum, samarium and praseodymium formates and acetates were synthesized and characterized in view of their use as precursors for the formati
- Devillers, M.,De Smet, F.,Tirions, O.
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- The synthesis of pure-phase bismuth ferrite in the Bi-Fe-O system under hydrothermal conditions without a mineralizer
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Bismuth ferrite, BiFeO3 (BFO), was synthesized in a hydrothermal process without the introduction of any metal cations, other than Fe 3+ and Bi3+. For this purpose, a strong organic hydroxide was used for the precipitation of the bismuth and iron salts. With the aim to study the molar range for the production of BFO in the Bi-Fe-O system under hydrothermal conditions, the complexity of the phases appearing after the reaction was investigated. Pure-phase BFO was achieved in the case of a hydrothermal treatment after the coprecipitation of a solution of bismuth and iron salts containing an equimolar ratio of Bi3+ and Fe3+ ions. Various iron and bismuth compounds having different morphologies were achieved by changing the Bi3+:Fe3+ ratios in the reaction, but no other bismuth iron oxide phases were observed. To obtain a complete picture of the compounds, we compared the results from transmission electron microscopy with those from X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The dielectric properties of the pure BFO and a multiphase system were compared. The pure BFO shows a higher dielectric permittivity than the multiphase system and is comparable with the values reported in the literature.
- Gajovic, Andreja,Sturm, Sago,JanWar, Bogtjan,Santic, Ana,Zagar, Kristina,Cehz, Miran
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- Manganese(III) chemistry in KOH solutions in the presence of Bi- or Ba-containing compounds and its implications on the rechargeability of γ-MnO2 in alkaline cells
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The influence of Bi- or Ba-containing compounds on the rechargeability of γ-MnO2 in alkaline electrolytes has been investigated with AA cells containing cylindrical cathodes and flooded cells containing thin-film type cathodes. In addition to the electrochemical evaluation of the cells, the discharged cathodes were analyzed by X-ray diffraction after washing and drying. The incorporation of bismuth or barium into the cathodes was found to improve the cell cyclabibility, which is partly due to the suppression of electrochemically inactive phases such as birnessite (δ-MnO2) and hausmannite (Mn3O4). A series of chemical oxidation reactions of Mn(OH)2 with H2O2 in KOH medium and nonredox reactions of Mn(III) acetate with KOH followed by an analysis of the solid and filtrate indicate that the Mn3+ ions, which were in equilibrium with the solid phases containing Mn(III), disproportionated into Mn(II) compounds and Mn(IV) oxides. Reaction mechanisms involving Mn(III) compounds in KOH solution and the role of bismuth or barium on those reactions are discussed.
- Im,Manthiram,Coffey
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- A simple preparation of carbon doped porous Bi2O3 with enhanced visible-light photocatalytic activity
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Carbon doped bismuth oxide (Bi2O3) with a porous structure is obtained by a simply calcination of bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) in glycol solution. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange (MO) in an aqueous solution under visible-light radiation (λ > 420 nm). The results show that carbon was incorporated into the lattice of Bi2O3. The absorption intensity of C-doped Bi2O3 increases in the region of 450-530 nm and the absorption edge has an obvious shift to long wavelength. The C-doped Bi2O3 exhibited much higher photocatalytic activity than the pure one due to the synergetic effects of the porous structure and the improved absorption in the visible-light region.
- Dai, Gaopeng,Liu, Suqin,Liang, Ying
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- Co2+ substituted for Bi3+ in BiVO4 and its enhanced photocatalytic activity under visible LED light irradiation
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We investigated the fabrication of Co-doped BiVO4 (Bi1-xCoxVO4+δ, 0.05 4. The X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) results indicated that the substitution of Co2+ ions for Bi3+ sites in BiVO4 was successful, although a change in the crystal phase of BiVO4 did not occur. UV-vis DRS and PL results suggested that the Co-incorporation could slightly improve the visible light absorption of BiVO4 and induce the separation of photoinduced electron-hole pairs; therefore, a significant enhancement of photocatalytic performance was achieved. The Bi0.8Co0.2VO4+δ sample showed superior photocatalytic activity in comparison with other samples, achieving 96.78% methylene blue (MB) removal within 180 min. In addition, the proposed mechanism of improved photocatalytic activities and the stability of the catalyst were also investigated.
- Nguyen, Trinh Duy,Bui, Quynh Thi Phuong,Le, Tien Bao,Altahtamouni,Vu, Khanh Bao,Vo, Dai-Viet N.,Le, Nhan Thi Hong,Luu, Tuan Duy,Hong, Seong Soo,Lim, Kwon Taek
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- In-situ growth UiO-66 on Bi2O3 to fabrication p-p heterojunction with enhanced visible-light degradation of tetracycline
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A p-p heterostructure has been constructed through loading UiO-66 on Bi2O3 as a composite photocatalyst to degrade the antibiotic tetracycline (TC) under visible light. The Bi2O3@UiO-66 composites were characterized by XRD, SEM, UV, BET, PL and FTIR. The formed p-p heterojunction improves the separation efficiency of electrons and holes, which caused the degradation rate constant of the composite photocatalyst for TC reaching 0.0492 min-1. The UiO-66 is added to improve the TC adsorption capacity and photocatalytic stability of the composite photocatalyst, so that the composite photocatalyst can have a photodegradation effect on TC under different anion and cation environments or a strong acid-base solution environment with the pH value of 1~13. The photoelectrochemical analyses is the evidence of the fast transfer of electron and hole pairs with inhibiting recombination.
- Duan, Zhengzhou,Hou, Dongmei,Li, Chuwen,Meng, Chunfeng,Tang, Jijun,Xv, Qinyun,Zhang, Qiyuan,Zhang, Tang,Zhang, Yamei,Zhu, Yu
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- Synthesis of Bi2O3@BiOI@UiO-66 composites with enhanced photocatalytic activity under visible light
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Bi2O3 is a photocatalyst with excellent performance; however, its applications are limited due to its wide bandgap. In this paper, by adding BiOI and the metal–organic framework UiO-66, a Bi2O3@BiOI@UiO-66 composite material is obtained with high adsorption capacity, in which the bandgap of Bi2O3 is reduced, the recombination of photogenerated electrons and holes is prevented, the photocatalytic efficiency and stability are improved. In visible light degradation experiments, Bi2O3@BiOI@UiO-66 has obvious degradation effects on Rhodamine B and tetracycline, which are 22.2 and 1.04 times that of pure Bi2O3, respectively. Bi2O3@BiOI@UiO-66 demonstrats its potential as photocatalytic degradation material.
- Tang, Jijun,Zhang, Tang,Duan, Zhengzhou,Li, Chuwen,Meng, Chunfeng,Zhang, Yamei,Zhang, Qiyuan,Hou, Dongmei,Xv, Qinyun,Zhu, Yu
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- Enhanced photocatalytic performance by Y-doped BiFeO3 particles derived from MOFs precursor based on band gap reduction and oxygen vacancies
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In order to improve the photocatalytic performance of BiFeO3, we prepared BiFeO3 nanoparticles doped with different molar concentrations of Y by thermal decomposition of MOFs precursor. The samples were characterized by XRD, TG, FESEM, XPS, UV-vis, and PL. The results of XRD and XPS reveal that Y3+ have been successfully incorporated into BiFeO3 lattice. FESEM and UV-vis results reveal that Y doping leads to a decrease in BiFeO3 particle size and band gap. PL shows that the recombination rate of photogenerated electron hole pairs of Bi0.95Y0.05FeO3 is the lowest. The influences of Y doping content on photocatalytic activity of BiFeO3 have been investigated. The results show that the best photocatalytic activity is Bi0.95Y0.05FeO3. Compared with pure BiFeO3, Bi0.95Y0.05FeO3 increased the degradation rate of MO by 1.3 times in 120 min. This may be due to the larger light response range and the lower photogenerated electron hole pairs recombination rate.
- Li, Zhendong,Cheng, Li,Zhang, Ke,Wang, Zhenhua
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- Oxygen Vacancy-Enhanced Ultrathin Bi2O3-Bi2WO6Nanosheets' Photocatalytic Performances under Visible Light Irradiation
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The oxygen vacancy caused by ultrathin structures would be introduced into the semiconductor photocatalyst to boost its photocatalytic activity. Herein, ultrathin Bi2O3-Bi2WO6 nanosheet composites have been successfully synthesized via a facile hydrothermal method. Compared to pure Bi2WO6 nanosheets, the Bi2O3-Bi2WO6 nanosheet composites possess abundant oxygen vacancies, which was confirmed by the positron annihilation spectra. The ultrathin Bi2O3-Bi2WO6 nanosheet composites exhibited remarkable photocatalytic degradation performance for oxytetracycline compared with that of pure Bi2WO6 nanosheets. The excellent photocatalytic activities of Bi2O3-Bi2WO6 composites could be attributed to the heterojunction structure and the oxygen vacancies caused by ultrathin structures.
- Bai, Jinwu,Ren, Xiaolei,Chen, Xue,Lu, Peng,Fu, Min
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p. 5049 - 5058
(2021/05/06)
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- CATALYST AND METHOD FOR PREPARING LIGHT OLEFIN USING DIRECT CONVERSION OF SYNGAS
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A catalyst for preparing light olefin using direct conversion of syngas is a composite catalyst and formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of component I is a metal oxide; and the component II is one or more than one of zeolite of CHA and AEI structures or metal modified CHA and/or AEI zeolite. A weight ratio of the active ingredients in the component Ito the component II is 0.1-20. The reaction process has high product yield and selectivity, wherein the sum of the selectivity of the propylene and butylene reaches 40-75%; and the sum of the selectivity of light olefin comprising ethylene, propylene and butylene can reach 50-90%. Meanwhile, the selectivity of a methane side product is less than 15%.
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Paragraph 0033; 0034-0038; 0043; 0044
(2021/04/30)
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- A gold(I) oxide double perovskite: Ba2AuIO6
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Oxide perovskites offer improved stability compared to halide perovskite compounds for optoelectronic applications. Here, we report the first gold-containing double perovskite, Ba2AuIO6, and compare it to Ba2AgIO6 and Ba2NaIO6. Ba2AuIO6 and Ba2AgIO6 exhibit a monoclinic distortion from the cubic perovskite structure possessed by Ba2NaIO6 and have similar lattice constants despite the nominally larger size of Au+ compared to Ag+. Ba2AgIO6 shows photoluminescence (PL) at 2.10 eV, and Ba2AuIO6 exhibits PL at 1.30 and 1.47 eV. As prepared, both compounds appear stable under visible light at room temperature but decompose when subjected to gentle heating followed by illumination. Our data suggest that this behavior is due to the presence of -OH defects in the crystal structures. This discovery provides a new route to semiconductors with a near-IR band gap and identifies engineering challenges that must be addressed to use oxide perovskites for optoelectronic devices.
- Abraham, John B. S.,Bond, Jack,Drichko, Natalia,Imperato, Cassandra,Mcqueen, Tyrel M.,Pogue, Elizabeth A.
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supporting information
p. 19033 - 19042
(2021/11/26)
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- One-pot synthesis of Bi2O3/Bi2O4 p-n heterojunction for highly efficient photocatalytic removal of organic pollutants under visible light irradiation
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Construction of p-n heterojunction is an effective strategy to obstacle the rapid recombination of photo-generated carriers for single photocatalyst. Herein, visible-light-active Bi2O3/Bi2O4 p-n junction was prepared by a one-pot hydrothermal method, using Bi(NO3)3·5H2O, KCl, and NaBiO3·2H2O as precursors. The in-situ formed BiOCl reacts with NaBiO3·2H2O during the hydrothermal process, producing the target product of Bi2O3/Bi2O4 p-n heterojunction. As expected, the obtained Bi2O3/Bi2O4 heterojunction photocatalysts exhibited higher photocatalytic activity than Bi2O4 for the degradation of MO (methyl orange) and phenol under visible-light irradiation. The superior photocatalytic performance of Bi2O3/Bi2O4 hybrid is mainly attributed to the improved separation efficiency of e--h+ pair induced by the internal electric field of p-n junction. The present work may provide a rational and facile strategy to construct a highly efficient Bi2O4-based p-n heterojunction photocatalyst toward pollutant removal.
- Li, Chengyu,Ma, Yaya,Zheng, Shizheng,Hu, Changyuan,Qin, Feng,Wei, Lin,Zhang, Cuiqing,Duo, Shuwang,Hu, Quanhong
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- A facile synthesis of a highly efficient β-Bi2O3/Bi2O2CO3heterojunction with enhanced photocatalytic NO oxidation under visible light
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The construction of a β-Bi2O3/Bi2O2CO3 heterojunction is an effective approach to separate the photogenerated charge carriers and to improve the photocatalytic performance of the semiconductor photocatalysts. In this study, a composite nanosheet of β-Bi2O3/Bi2O2CO3 was fabricated via an in situ annealing of Bi2O2CO3 at 380 °C. The composite showed an excellent adsorption toward NO and an enhanced photocatalytic efficiency over NO oxidation from 5.7 v/v% (bare Bi2O2CO3) to 32.5 v/v% (β-Bi2O3/Bi2O2CO3). Furthermore, the presence of the β-Bi2O3/Bi2O2CO3 heterojunction promoted the formation of additional O2-, and then improved the NO oxidation activity and safety of BOC in conjunction with OH. This journal is
- Deng, Zhaoqi,Hao, Yaru,Song, Xijia,Zhao, Ziquan
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p. 10989 - 10993
(2020/07/15)
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- Bismuth MOF-derived BiOBr/Bi24O31Br10heterojunctions with enhanced visible-light photocatalytic performance
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In this work, a hierarchical BiOBr/Bi24O31Br10 heterojunction is prepared for the first time from a bismuth MOF (Bi-BTC) by a facile bromination-annealing route. Since cetyltrimethylammonium bromide (CTAB) is used as the Br element source, the heterojunction constructed of BiOBr and Bi24O31Br10 nanosheets maintains the rod-like morphology of the original MOF. In photocatalytic degradation tests, the BiOBr/Bi24O31Br10 heterojunction exhibits much higher photocatalytic activity than pure Bi2O3, and the heterojunctions annealed at 450 °C show the best photocatalytic activity among samples prepared at various temperatures. The heterojunction also shows good pH adaptability, good reusability, and structural stability for RhB degradation, and the TOC results and full UV-vis spectra confirm its good mineralization performance under visible-light irradiation. Based on the photo-electrochemical characterization and free radical tests, a photocatalytic enhancement mechanism over the heterojunction and different photocatalytic reactions in the presence of photo-induced h+, O2- and 1O2 are reasonably proposed.
- Huang, Ganghong,Huang, Jing,Li, Zishun,Liu, Kun,Tang, Xuekun,Zhang, Guofan
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p. 4645 - 4654
(2020/08/10)
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- Insights into the impurities of Bi2WO6synthesized using the hydrothermal method
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Bismuth tungstate (Bi2WO6) nanomaterials are widely used as visible-light driven photocatalysts. However, limited attention has been paid to the purity of prepared Bi2WO6 nanoparticles, which may affect the photocatalytic performance and hinder in-depth study of Bi2WO6. In this work, the impurities of Bi2WO6 formed during the hydrothermal process under a wide range of acid-base conditions (from 1.5 M HNO3 to 0.5 M NaOH) were qualitatively analyzed and accurately quantified for the first time. After confirmation of Bi2WO6 stability, the impurities were dissolved using acid or base treatment, followed by measurements of the ion concentrations using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Furthermore, various characterization techniques including XRD, FE-SEM, TEM, UV-Vis DRS, XPS and FTIR were implemented to explore the change in morphology and optical properties of Bi2WO6 prepared in different acid-base environments, and to facilitate qualitative analysis of impurities. The hydrolytic properties of raw materials used for the synthesis of Bi2WO6 were also analyzed with UV-Vis transmittance observation. Following these analyses, the types and contents of impurities in Bi2WO6 prepared by the hydrothermal method under different acid-base conditions were determined. Results show that the primary impurity is WO3·0.33H2O (41.09%) for the precursor prepared in 1.5 M nitric acid solution. When the pH of the precursor was in the range of 0.97-7.01, the synthesized Bi2WO6 has relatively high purity, and the impure products were identified as BiONO3. Bi2O3 began to appear when pH reached 9.01 and it reached 18.88% when pH was 12.98. The final product was Bi2O3 exclusively for the precursor conditioned in 0.5 M NaOH solution. In addition, the accuracy of the proposed quantitative method using ICP-MS was validated for several scenarios by weight difference experiments. This journal is
- Liu, Jiayou,Luo, Yulin,Nie, Qianqian,Tan, Zhongchao,Wang, Shuai,Yu, Hesheng
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p. 40597 - 40607
(2020/11/23)
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- Improved photoelectrode performance of chemical solution-derived Bi2O3crystals: Via manipulation of crystal characterization
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Three-dimensional Bi2O3 crystals with various morphologies were successfully synthesized on F-doped tin oxide substrates with and without homoseed layers via chemical bath deposition (CBD) routes. The structural analysis reveals that control of the pH value of the reaction solution resulted in as-grown Bi2O3 crystals with nanosheet and plate morphologies. A lower pH value of the reaction solution engendered formation of a porous sheet-like morphology of Bi2O3; by contrast, a higher pH value of the reaction solution is favorable for formation of solid Bi2O3 plates on the substrates. Furthermore, a sputter coated Bi2O3 seed layer with dual α- and β-Bi2O3 phases plays an important role in the CBD-derived Bi2O3 crystallographic structures. The Bi2O3 crystals formed via CBD processes without a sputter coated Bi2O3 homoseed layer demonstrated a high purity in β-Bi2O3 phase; those grown with a homoseed layer exhibited a dual α/β phase. The photoactive performance results show that construction of an α/β-Bi2O3 homojunction in the CBD-derived Bi2O3 crystals substantially improved their photoactive performance. Comparatively, the porous Bi2O3 nanosheets with a dual α/β-Bi2O3 phase demonstrated the highest photoactive performance among various Bi2O3 crystals in this study. The superior photoactivity of the porous α/β-Bi2O3 nanosheets herein is attributed to their high light absorption capacity and photoinduced charge separation efficiency. The experimental results in this study provide a promising approach to design CBD-derived Bi2O3 crystals with desirable photoelectric conversion functions via facile morphology control and seed layer crystal engineering. This journal is
- Chou, Yu-Hsun,Liang, Yuan-Chang
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p. 45042 - 45058
(2020/12/30)
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- Heteroatom-induced band-reconstruction of metal vanadates for photocatalytic cyclohexane oxidation towards KA-oil selectivity
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Structure-function correlation constitutes a central theme in the selective photocatalytic oxidation of cyclohexane with molecular oxygen, as a result of precise tailoring band-structure towards KA-oil selectivity. Herein, we comparatively and systematically investigate the correlation among optical properties, electronic structure, and photocatalytic performance of two d°-vanadate photocatalysts (BiVO4 and Cu3V2O8) using theoretical calculations and experimental techniques. Results show that BiVO4 promotes the selective oxidation pathway under visible-light irradiation with higher efficiency (TOF = 7.5 h?1, based on the molar amount of V sites) and chemoselectivity (cyclohexanone/cyclohexanol molar ratio = 3.0) than the Cu3V2O8. Meanwhile, the photocatalytic performance of BiVO4 demonstrates high photocatalytic selectivity towards KA-oil (95%), while Cu3V2O8 seems to facilitate the accommodation of chlorine promoters, leading to very different chlorocyclohexane selectivity (46%). Such the distinct photocatalytic performances of BiVO4 and Cu3V2O8 can be ascribed to their unique electronic structures to facilitate the e??h+ charge carriers and generation of reactive species during photoirradiation. The Bi3+ 6p states of BiVO4 are predominant components of the conduction band minimum (CBM) and hybridize with Bi3+ 6 s, and O2? 2p and V5+ 3d orbitals at the valence band maximum (VBM); whereas the Cu2+ 3d and V5+ 3d orbitals contribute to the CBM of Cu3V2O8, and Cu2+ 3d, O2? 2p and V5+ 3d orbitals at the VBM. So BiVO4 with s ? p matrix elements is more effective than the Cu3V2O8 in producing [rad]OH, h+ and H2O2, which can rapidly oxidize the C ? Cl band cleavage for chlorocyclohexane intermediate to regenerate newly Cl[rad] radicals in the next cycle reactions. Heteroatom-tuning of photocatalytic performance is further supported by universal evidences from experimental results by replacing Bi or Cu of the above vanadates with Ag, La, Sr, Fe or Ti atom and the study of the electrons, holes and radicals mediated reaction pathway by scavengers, respectively.
- Xiang, Liping,Fan, Jingjing,Zhong, Wenzhou,Mao, Liqiu,You, Kuiyi,Yin, Dulin
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p. 120 - 131
(2019/02/25)
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- Oxygen-Vacancy-Mediated Photocatalysis over Bi2Sn2O7: Exceptional Catalytic Activity and Selectivity
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A series of Bi2Sn2O7 photocatalysts was developed with the aim to regulate defect chemistry as well as electronic structure by modulating the charge states of tin species for boosting photocatalytic selective oxidation of alcohols performance. Defective centers, such as oxygen vacancies (OVs), were beneficial to enhancing the adsorption and activation of molecular oxygen. Meanwhile, the valence band edge potential of Bi2Sn2O7 with higher OVs content exhibited a distinct downshift, improving the thermodynamical driving force of photooxidation. Additionally, OVs contributed to promoting the separation efficiency of photogenerated carriers, which can be confirmed by the surface photovoltage measurement. By optimizing the electronic structure as well as defect chemistry, the optimal benzyl alcohol conversion efficiency was 76.0 % with selectivity toward benzaldehyde being about 100 %. It's found that photogenerated holes and .O2 ? active species played critical role in photocatalytic aerobic oxidation. This work may provide a novel insight to clarify the role of defect chemistry during the selective benzyl alcohol oxidation over Bi2Sn2O7 photocatalyst.
- Huang, Shushu,Kou, Xin,He, Dan,Du, Chunfang,Wang, Xiaojing,Su, Yiguo
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p. 6316 - 6323
(2019/05/27)
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- Iodine-Deficient BiO1.2I0.6 Coupling with Bi2O3 for Degradation of Volatile Organic Compounds under Simulated Sunlight Irradiation
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A photocatalyst with a high separation efficiency of carriers is crucial for the photocatalytic efficient decomposition of volatile organic compounds (VOCs). In this work, a new iodine-deficient BiO1.2I0.6/Bi2O3 photocatalyst was developed through a solvothermal approach coupled with thermal decomposition. The 2 wt % BiO1.2I0.6/Bi2O3 sample demonstrated optimal photocatalytic activity for the degradation of toluene, achieving a 55.1 % mineralization ratio under 8 h of irradiation, which was 14.9 and 2.1 times higher than those of BiO1.2I0.6 and Bi2O3, respectively. Compared with BiO1.2I0.6 and Bi2O3, 2 wt % BiO1.2I0.6/Bi2O3 exhibited the weakest fluorescence band, highest photocurrent density, and lowest impedance; thus suggesting that Bi2O3 compounded by 2 wt % BiO1.2I0.6 distinctly promoted the separation efficiency of carriers. The hydroxyl radical (.OH) was the main active species, apart from holes, for the photocatalytic degradation of toluene.
- Wang, Shaomang,Guan, Yuan,Zeng, Ruiheng,Zhang, Zhijun,Liu, Liang,Li, Zhongyu,An, Wen,Fu, Yang
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p. 4874 - 4881
(2019/11/13)
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- Z-scheme MoS2/Bi2O3 heterojunctions: Enhanced photocatalytic degradation performance and mechanistic insight
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A new Z-scheme MoS2/Bi2O3 heterojunction photocatalyst was successfully prepared using a facile and practical hydrothermal method. The Z-scheme MoS2/Bi2O3 heterojunction exhibits a superior degradation efficiency compared to pure MoS2 and Bi2O3 for removing industrial and domestic pollutants under visible light, such as 2-mercaptobenzothiazole, tetracycline and rhodamine B. The enhancement in the photocatalytic performance mainly stems from the interfacial interaction between the MoS2 nanosheets and Bi2O3 rods, which can increase the specific surface area and accelerate the separation of the photo-induced electron-hole pairs. To explain this interfacial interaction between MoS2 and Bi2O3 in the Z-scheme MoS2/Bi2O3 heterojunction, several characterization techniques were applied. In addition, the photocatalytic mechanism for degrading pollutants was demonstrated using trapping experiments and electron spin resonance. This work could provide a promising approach for the formation of other Z-scheme transition metal compound heterojunctions with outstanding photocatalytic activity.
- Ji, Rong,Ma, Changchang,Ma, Wei,Liu, Yang,Zhu, Zhi,Yan, Yongsheng
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supporting information
p. 11876 - 11886
(2019/08/07)
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- Studies on the thermal stability of BiFeO3 and the phase diagram of Bi-Fe-O system
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The thermal stability of BiFeO3 was examined by different experimental techniques and found that it is metastable at low temperatures and it attains thermodynamic stability at around 940 K. Long term equilibration studies at 773 and 1023 K, and characterization of coexisting phases by XRD revealed the phase fields. Based on this, the isothermal section of the ternary phase diagram of Bi-Fe-O system was constructed at 773 and 1023 K.
- Meera,Ganesan, Rajesh,Gnanasekaran
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p. 1108 - 1118
(2019/03/28)
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- Boosting Electrochemical Reduction of CO2 at a Low Overpotential by Amorphous Ag-Bi-S-O Decorated Bi0 Nanocrystals
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Bimetal-S-O composites have been rarely researched in electrochemical reduction of CO2. Now, an amorphous Ag-Bi-S-O decorated Bi0 catalyst derived from Ag0.95BiS0.75O3.1 nanorods by electrochemical pre-treatment was used for catalyzing eCO2RR, which exhibited a formate FE of 94.3 % with a formate partial current density of 12.52 mA cm?2 at an overpotential of only 450 mV. This superior performance was attributed to the attached amorphous Ag-Bi-S-O substance. S could be retained in the amorphous region after electrochemical pre-treatment only in samples derived from metal-S-O composites, and it would greatly enhance the formate selectivity by accelerating the dissociation of H2O. The existence of Ag would increase the current density, resulting in a higher local pH, which made the role of S in activating H2O more significantly and suppressed H2 evolution more effectively, thus endowing the catalyst with a higher formate FE at low overpotentials.
- Zhou, Jun-Hao,Yuan, Kun,Zhou, Liang,Guo, Yu,Luo, Ming-Yu,Guo, Xiao-Yan,Meng, Qing-Yuan,Zhang, Ya-Wen
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supporting information
p. 14197 - 14201
(2019/09/03)
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- Transesterification of dimethyl carbonate and phenol to diphenyl carbonate with the bismuth compounds
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Bismuth oxide was first employed for the transesterification of dimethyl carbonate with phenol to diphenyl carbonate, which has excellent catalytic activity. With 0.4?g Bi2O3, the phenol conversion of 46.4% and transesterification selectivity of 99.9% were attained. The characterization of the used sample by XRD, FTIR and solid-state 13C-NMR indicate that a new compound of bismuth phenoxide was formed with the disappearance of bismuth oxide. It was evidenced that the bismuth phenoxide act as the role of active phase in the transesterification, which was generated facilely in situ by the reaction of bismuth oxide added with the raw material of phenol. The bismuth phenoxide presents excellent reusability, after four consecutive runs, the phenol conversion remained above 45%, and the transesterification selectivity was maintained at 99.9%.
- Xiao, Zhongliang,Yang, Hao,Zhang, Hua,Chen, Tong,Wang, Gongying
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p. 2347 - 2352
(2018/08/06)
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- Citric acid-assisted hydrothermal synthesis of a self-modified Bi2SiO5/Bi12SiO20 heterojunction for efficient photocatalytic degradation of aqueous pollutants
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A self-modified Bi2SiO5/Bi12SiO20 heterojunction was synthesized for the first time via a citric acid-assisted hydrothermal method. It was found that citric acid (CA) played two roles in the formation of the Bi2SiO5/Bi12SiO20 heterojunction: enhancement of the specific surface area due to the release of many volatiles from the decomposition of CA and tuning the weight ratio of Bi2SiO5 and Bi12SiO20 in the heterojunction by forming different complexes with Bi3+. Thus, a self-modified Bi2SiO5/Bi12SiO20 heterojunction prepared at a CA dosage of 11.25 mmol presented an I27.9:I29.2 value of 1.52 and a BET specific surface area of 32.6 m2 g-1, 5.7 times that without addition of CA. It showed the highest first-order apparent reaction constant of 0.1694 min-1 in the photocatalytic degradation of acid orange 7 (AO7), which is 1.8, 53.0, and 2.2 times that of Bi2SiO5, Bi12SiO20, and TiO2 (P25), respectively. The capture experiments show that the main active species that degraded AO7 are not O2- and OH but h+vb. During the AO7 degradation, four intermediates, sulfonic acid, oxalic acid, benzenesulfonic acid, and 4-aminobenzenesulfonic acid, were identified by capillary electrophoresis/capacitively coupled contactless conductivity detection. Finally, other pollutants, rhodamine B, p-chlorophenol, and tetracycline, were also found to be efficiently removed by the Bi2SiO5/Bi12SiO20-mediated photocatalysis system.
- Li,Wen,Tian,Shan,Xiong
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p. 1051 - 1061
(2018/03/05)
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- The formation of a direct Z-scheme Bi2O3/MoO3 composite nanocatalyst with improved photocatalytic activity under visible light
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A direct Z-scheme photocatalyst Bi2O3/MoO3 was prepared via hydrothermal method and mixing-calcination methods. The as-obtained Bi2O3/MoO3 composites exhibit higher photocatalytic activities than pure Bi2O3 and MoO3 for degradation of methylene blue (MB) under visible light irradiation. The increased photocatalytic activity is mainly attributed to the efficient separation of photogenerated charge carriers through a Z-scheme system between Bi2O3 and MoO3. Furthermore, the results of energy band positions, active species trapping experiments and photoluminescence spectroscopy (PL) provide direct evidence of an efficient Z-scheme as the main mechanism for degradation of MB under visible light irradiation over Bi2O3/MoO3 composites.
- Hu, Zeshu,Zhou, Jiabin,Zhang, Ying,Liu, Wei,Zhou, Jun,Cai, Weiquan
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p. 208 - 214
(2018/06/14)
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- Synthesis of Bi2O3-Bi4V2O11 heterojunctions with high interface quality for enhanced visible light photocatalysis in degradation of high-concentration phenol and MO dyes
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One-dimensional Bi2O3-Bi4V2O11 heterostructures with enhanced visible light photocatalytic performance were synthesized by high temperature calcination of Bi(OHC2O4)·2H2O-Bi2VO5.5 precursors. The Bi4V2O11 nanosheets uniformly grew on the Bi2O3 porous rods by crystallographic-oriented epitaxial growth, which increased the interface quality and then provided the smallest penetration barrier for electron-hole pair transfer between Bi2O3-Bi4V2O11 interfaces. The photocatalytic performance of the obtained products was evaluated by degradation of phenol and methyl orange (MO) with high concentration under visible light irradiation. The results show that the Bi2O3-Bi4V2O11 heterostructure displays higher photocatalytic activity than pure phase Bi2O3 and Bi4V2O11, and more encouragingly, 40 mg L-1 of phenol can be completely degraded in 30 min under visible light irradiation using the Bi2O3-Bi4V2O11 (DS-2) heterostructure as the photocatalyst. This enhanced photocatalytic performance is ascribed to the synergistic effect of the suitable band alignment of the Bi2O3 and Bi4V2O11, high interface quality and one-dimensionally ordered nanostructure. Radical scavenger experiments indicate that holes (h+) and superoxide radicals (O2-) were the main active species for phenol (and MO) degradation during the photocatalytic process. This work would offer a simple route to design and fabricate junction structures with high interface quality for photocatalytic applications.
- Liu, Ting,Mao, Yan Ge,Peng, Yin
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p. 2553 - 2561
(2018/05/23)
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- Preparation and Performance of Visible-Light-Driven Bi2O3/ZnS Heterojunction Functionalized Porous CA Membranes for Effective Degradation of Rhodamine B
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Photocatalytic degradation is an effective method for fast removal of dye-contaminated water. In the present work, a bismuth oxide/zinc sulfide-cellulose acetate photocatalytic membrane (Bi2O3/ZnS-CA) is successfully fabricated via the phase-inversion method with a Bi2O3/ZnS heterojunction as the photocatalyst. The Bi2O3/ZnS-CA membranes shows high photocatalytic activity in degradation of Rhodamine B (RhB) under visible-light irradiation due to the Bi2O3/ZnS heterojunction structure contributing to the high efficiency of photogenerated charge separation. The photodegradation efficiency of Bi2O3/ZnS-CA membrane is significantly enhanced (about 30% improvement) and the photodegradation kinetic is four times faster than that of the Bi2O3-CA and the ZnS-CA membranes. Moreover, the Bi2O3/ZnS-CA membrane exhibits excellent permeation flux (649.7 L m?2 h?1) and high porosity (69.94%). The Bi2O3/ZnS-CA membrane also shows good adsorption performance of RhB, which could enhance the interaction between RhB and the catalyst. This work provides a new sight to construct highly effective visible-light-driven photocatalytic membranes for continuous organic dye treatment.
- Li, Binrong,Chu, Jinyu,Li, Yi,Meng, Minjia,Cui, Yanhua,Li, Qidi,Feng, Yonghai
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- Metastable Bi2Zr2O7 with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties
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Equimolar concentrations of Zr4+ and Bi3+ were chelated with ethylenediaminetetraacetic acid ligand with the purpose of using it as a precursor to generate pyrochlore-like Bi2Zr2O7. When the X-ray amorphous precursor was calcined at 750 °C for 3 h in air, pyrochlore-like product with superstructure reflections was identified by powder X-ray diffraction (PXRD) along with one minor reflection due to β-Bi2O3. This phase was found to be metastable from additional experiments conducted by varying calcination conditions. Structural refinement of PXRD pattern by Le Bail method in Fd3m space group yielded cubic lattice constant of 10.8421(27) ?. Flower-petal-like morphology of the sample was evident in its field-emission scanning electron microscopy image and energy-dispersive X-ray analysis performed at various locations of the specimen confirmed nearly equal concentration of zirconium and bismuth. Six bands at 260, 320, 448, 531, 597, and 828 cm-1 were observed for this sample in its Raman spectrum and supported our claim of pyrochlore-like structure. Indexation of bright spots present in selected area electron diffraction pattern and observed distances of lattice fringes in high-resolution transmission electron microscopy image were in conformity with the results from PXRD measurements. Absorbance maxima at 312, 372, and 423 nm with a broad tailing stretching up to visible region was noticed in the UV-visible spectrum of this sample. Direct band gap of 2 eV was estimated for this sample from Tauc plot. The oxygen ion conductivity of the sample in the temperature range of 333-773 K was examined, and the highest conductivity at 773 K was 3.071 × 10-6 S/cm. From activation energy estimation and dielectric loss analysis, thermally activated process related to the mobility of oxygen ion vacancy was found responsible for the observed ionic conductivity. A similar conclusion was reached after careful analysis of dielectric spectroscopy data of this sample. High surface area (125.04 m2/g) and mesoporosity (pore diameter of 3.81 nm) were possessed by this sample, which paved way for studying its catalytic role in the reduction of nitroaromatics and carcinogenic Cr6+. Cyclability experiments showed the retainment of catalytic activity up to five cycles by the sample without undergoing any structural change.
- Pandey, Jyoti,Shrivastava, Vipul,Nagarajan, Rajamani
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p. 13667 - 13678
(2018/10/24)
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- Efficient Solar-Driven Hydrogen Transfer by Bismuth-Based Photocatalyst with Engineered Basic Sites
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Photocatalytic organic conversions involving a hydrogen transfer (HT) step have attracted much attention, but the efficiency and selectivity under visible light irradiation still needs to be significantly enhanced. Here we have developed a noble metal-free, basic-site engineered bismuth oxybromide [Bi24O31Br10(OH)] that can accelerate the photocatalytic HT step in both reduction and oxidation reactions, i.e., nitrobenzene to azo/azoxybenzene, quinones to quinols, thiones to thiols, and alcohols to ketones under visible light irradiation and ambient conditions. Remarkably, quantum efficiencies of 42% and 32% for the nitrobenzene reduction can be reached under 410 and 450 nm irradiation, respectively. The Bi24O31Br10(OH) photocatalyst also exhibits excellent performance in up-scaling and stability under visible light and even solar irradiation, revealing economic potential for industrial applications.
- Dai, Yitao,Li, Chao,Shen, Yanbin,Zhu, Shujie,Hvid, Mathias S.,Wu, Lai-Chin,Skibsted, J?rgen,Li, Yongwang,Niemantsverdriet, J. W. Hans,Besenbacher, Flemming,Lock, Nina,Su, Ren
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supporting information
p. 16711 - 16719
(2018/12/11)
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- Efficient photocatalytic reduction of dinitrogen to ammonia on bismuth monoxide quantum dots
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N2 reduction to ammonia by solar light represents a green and sustainable ammonia synthesis approach which helps to suppress the global warming and energy crisis. However, conventional semiconductors usually suffer from low activity or poor stability, largely suppressing the application of this technology. Here, we report that bismuth monoxide (BiO) quantum dots with an average size of 2-5 nm exhibited efficient photocatalytic activity for ammonia synthesis under simulated solar light. A highly efficient ammonia synthesis rate of 1226 μmol g?1 h?1 is achieved without the assistance of any sacrificial agent or co-catalyst, which is about 1000 times higher than that using the traditional Fe-TiO2 photocatalyst. Kinetic analysis reveals that the synergy of three low valence surface Bi(ii) species markedly enhances N2 activation by electron donation, which finally resulted in the highly efficient N2 photoreduction performance. This work will shed light on designing efficient and robust N2 reduction photocatalysts.
- Sun, Songmei,An, Qi,Wang, Wenzhong,Zhang, Ling,Liu, Jianjun,Goddard III, William A.
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p. 201 - 209
(2016/12/27)
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- Facile synthesis of porous Bi2O3-BiVO4p-n heterojunction composite microrods with highly efficient photocatalytic degradation of phenol
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In the present work, high-quality porous Bi2O3-BiVO4composite microrods (CMRs) with a uniform size distribution have been successfully prepared through a facile solvothermal method followed by an annealing treatment, in which Bi(OH)C2O4-BiVO4precursors were first synthesized using Na2C2O4and NaVO3as starting materials and then thermally decomposed to produce porous Bi2O3-BiVO4p-n heterojunction CMRs. The as-prepared Bi2O3-BiVO4product was characterized by UV–Vis diffuse reflectance spectroscopy (DRS) and valence-band X-ray photoelectron spectroscopy (XPS). Significantly enhanced photocatalytic activity in degrading colorless organic phenol under visible-light illumination (λ?>?420?nm) was observed with the porous CMRs, more than 48 times higher than that of the mixture of BiVO4and Bi2O3, and 192 and 160 times higher than pure BiVO4and Bi2O3, respectively. A direct Z-scheme mechanism was employed to describe the transfer of photogenerated electrons and holes in the Bi2O3-BiVO4CMR system, and the dramatically enhancement of the observed photoactivity may be attributed to the high separation efficiency of electron-hole pairs, resulting from the p-n heterojunction formed in the porous structure.
- Mao, Mengmeng,Chen, Fang,Zheng, Changcheng,Ning, Jiqiang,Zhong, Yijun,Hu, Yong
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supporting information
p. 1080 - 1087
(2016/07/26)
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- Optical nonlinearity in multiferroic bismuth ferrite
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Bismuth ferrite (BFO) nanoparticles were synthesized via sol-gel route with malic acid as a chelating agent. Structural characterization by XRD reveals the formation of single phase rhombohedral BFO and FTIR (433, 546?cm?1) confirms the molecular structure. FESEM exhibits an agglomerated spherical morphology with an average particle size of 119?nm. The first and second order structural transitions have been detected at 821 (rhombohedral – orthorhombic) and 932?°C (orthorhombic – cubic) by DTA. Strong visible light absorption with a band gap of 1.92?eV and defect related emissions at blue (417,450?nm) and green (521?nm) regions have been observed. Multiferroic properties at room temperature show weak ferromagnetism with remnant magnetization (Mr) 0.179 emu/gm and ferroelectric behavior with remnant polarization (Pr) 0.08?μC/cm2. Dielectric measurements as a function of frequency (100?Hz–5?MHz) and temperature (30–450?°C) illustrate an evidence for magnetoelectric coupling with a peak at 350?°C indicating the magnetic phase transition. Third order nonlinear optical property studied by the open aperture Z-scan technique (Nd: YAG, 532?nm, 5?ns) shows the reverse saturable absorption (RSA) based optical limiting behavior.
- Francis, P. Nisha,Dhanuskodi,Muneeswaran,Thomas, Anitta Rose,Giridharan
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p. 796 - 802
(2016/07/22)
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- The enhanced photocatalytic activity and self-cleaning properties of mesoporous SiO2 coated Cu-Bi2O3 thin films
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Mesoporous SiO2 coated Cu-Bi2O3 thin films (meso-SiO2/Cu-Bi2O3) were prepared on glass substrates using a simple sol-gel/spin-coating method. The structure and optical properties were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, a UV-vis spectrophotometer and a water contact angle meter. The photocatalytic activity and self-cleaning properties of the films were investigated through the degradation of methyl orange and stearic acid, respectively. It was found that the meso-SiO2/Cu-Bi2O3 thin films were highly transparent and showed excellent superhydrophilicity even in the dark. The thin films exhibited enhanced photocatalytic activity and self-cleaning properties compared to pure Bi2O3 films, which was attributed to the cooperation of the interfacial charge transfer between Bi2O3 and surface Cu species as well as the unique mesoporous SiO2 structure. The results showed that the films can be used as promising self-cleaning and antifogging materials.
- Shan, Wenjie,Hu, Yun,Zheng, Mengmeng,Wei, Chaohai
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p. 7428 - 7436
(2015/04/27)
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- Microstructure and charge carrier dynamics in Dy substituted phase stabilized cubic Bi2O3
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Room temperature phase stabilization of cubic Bi2O3 has been achieved by adding Dy2O3 as the dopant, using a low temperature citrate-auto-ignition method. The samples were sintered at different temperatures retaining the cubic fluorite structure. Rietveld refinement of the X-ray diffraction profiles has given detailed microstructural information of the prepared samples. The transmission electron micrographs confirmed the presence of atomic planes as obtained from X-ray diffraction. The UV-Vis spectra show a red shift of the absorption peak with the increase in sintering temperature. Impedance spectroscopy studies of the samples exhibited thermally activated non-Debye type relaxation process. In addition, studies of the electrical conductivity have suggested the negative temperature coefficient of resistance (NTCR) behavior of the samples. The comparable values of activation energies, obtained from different parameters, indicated that the ions follow the same type of mechanism for conduction as well as for relaxation. The temperature independence of the mechanisms has been confirmed from scaling of different spectra. The correlation between structural and electrical properties of the samples has been discussed and interpreted accordingly.
- Bandyopadhyay, Swagata,Dutta, Abhigyan
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p. 65123 - 65132
(2015/08/18)
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