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Cas Database

7732-18-5

7732-18-5

Identification

  • Product Name:Water

  • CAS Number: 7732-18-5

  • EINECS:215-185-5

  • Molecular Weight:18.0153

  • Molecular Formula: H2O

  • HS Code:3303000000

  • Mol File:7732-18-5.mol

Synonyms:caustic soda liquid;Aquafina;Distilled water;Hydrogen oxide (H2O);UltrexII Ultrapure;

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Safety information and MSDS view more

  • Pictogram(s):CorrosiveC

  • Hazard Codes: Xn:Harmful;

  • Signal Word:No signal word.

  • Hazard Statement:none

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician. In case of skin contact Wash off with soap and plenty of water. Consult a physician. In case of eye contact Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

  • Fire-fighting measures: Suitable extinguishing media Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Pick up and arrange disposal. Sweep up and shovel. Keep in suitable, closed containers for disposal.

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. Store in cool place. Keep container tightly closed in a dry and well-ventilated place.

  • Exposure controls/personal protection:Occupational Exposure limit valuesBiological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 918 Articles be found

Oxygen electroreduction on heat-treated multi-walled carbon nanotubes supported iron polyphthalocyanine in acid media

Zhang, Rui,Peng, Yingxiang,Li, Zhipan,Li, Kai,Ma, Jie,Liao, Yi,Zheng, Lirong,Zuo, Xia,Xia, Dingguo

, p. 343 - 351 (2014)

Multi-walled carbon nanotubes (MWCNTs) supported iron phthalocyanine (FePc), binuclear iron phthalocyanine (bi-FePc) and iron polyphthalocyanine (FePPc) were prepared by a solvothermal process. The resulting FePc/MWCNTs, bi-FePc/MWCNTs and FePPc/MWCNTs were heat-treated in argon (Ar) atmosphere at various temperatures ranging from 500 to 900°C to obtain optimized catalysts for the oxygen reduction reaction (ORR). The crystal structure, morphology and chemical environment of the catalysts were examined by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS). The electrocatalytic activity of the obtained catalysts was measured using a rotating disk electrode (RDE) technique in 0.5 mol L-1 H2SO4 solution saturated with oxygen. The ORR activity of the heat-treated FePPc/MWCNTs was found to be better than that of the heat-treated bi-FePc/MWCNTs and FePc/MWCNTs. Furthermore, the heat-treatment temperature greatly influenced the catalytic ORR ability of the catalysts. The FePPc/MWCNTs heat-treated at 800°C exhibited a four-electron transfer process and the best ORR activity (EORR = 0.79 V vs. RHE), methanol resistance, and stability (current loss = 13% at -0.13 V vs. Hg/Hg2SO4 after 55 h). XPS indicated that pyridine-type nitrogen, not graphitic-N, played a critical role in determining the electrocatalytic ORR activity of the amples. XAFS showed that the coordination geometry around Fe was close to square planar in structure, suggesting that the Fe-N4 structure was produced by the high temperature treatment.

Guentherschulze, A.

, p. 358 - 379 (1928)

Ni2P hollow microspheres for electrocatalytic oxygen evolution and reduction reactions

Lei, Haitao,Chen, Mingxing,Liang, Zuozhong,Liu, Chengyu,Zhang, Wei,Cao, Rui

, p. 2289 - 2293 (2018)

H2 generated by solar-driven water splitting is a clean and environmentally benign fuel and is an ideal alternative to replace fossil fuels, whose uses have caused a series of energy and environmental issues. The synthesis of Ni2P and its catalytic properties foroxygen evolution reduction (OER) and oxygen reduction reaction (ORR) was reported. The as-prepared Ni2P material has a hollow microsphere structure, which has a very high surface-to-volume ratio and is beneficial for fast charge transfer and mass diffusion. These features are useful for electrocatalysis. The high activities and stabilities of this Ni2P material for both OER and ORR were confirmed, representing a rare example of bifunctional OER and ORR catalysts among Ni phosphides. Results showed that NI2P can catalyze water oxidation, achieving a 10 mA cm-2 current density at a 280 mV overpotential and can catalyze the selective four-electron reduction of O2 to H2O at an onset potential of 0.92 V, making it one of the most active metal phosphide catalysts for OER and ORR.

Tuning Cobalt and Nitrogen Co-Doped Carbon to Maximize Catalytic Sites on a Superabsorbent Resin for Efficient Oxygen Reduction

Liu, Mengran,Lin, Hai,Mei, Zongwei,Yang, Jinlong,Lin, Jie,Liu, Yidong,Pan, Feng

, p. 3631 - 3639 (2018)

The electrocatalytic performance and cost of oxygen reduction reaction (ORR) catalysts are crucial to many renewable energy conversion and storage systems/devices. Recently, transition-metal/nitrogen-doping carbon catalysts (M–N–C) have attracted tremendous attention due to their low cost and excellent catalytic activities; however, they are restricted in large-scale commercial applications by complex preparation processing. Here, a facile strategy to prepare Co–N–C catalysts has been developed. A kind of superabsorbent resin normally found in diapers, poly(acrylic acid-acrylamide), is used to adsorb a transition-metal cobalt salt and a pyrolysis strategy at 800 °C under an argon atmosphere is followed. The resin simultaneously plays a multiple role, which includes structural support, dispersing cobalt ions by coordinate bonds, and providing a carbon and nitrogen source. Attributed to the conductive carbon frameworks and abundant catalytic sites, the Co–N–C catalyst exhibits an excellent electrocatalytic performance. High onset potential (0.96 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.80 V vs. RHE), and a large diffusion-limited current density (4.65 mA cm?2) are achieved for the ORR, which are comparable or superior to the commercial 20 % Pt/C and reported M–N–C ORR electrocatalysts. This work provides a universal dispersion technology for Co–N–C catalyst, which makes it a very promising candidate toward the ORR.

Caley,Brundin

, p. 142 (1953)

Synthesis, electrochemistry and electrocatalytic activity of cobalt phthalocyanine complexes – Effects of substituents for oxygen reduction reaction

Acar, Elif Turker,Tabakoglu, Tuba Akk?zlar,Atilla, Devrim,Yuksel, Fatma,Atun, Gulten

, p. 114 - 124 (2018)

The synthesis, characterization, electrochemistry and electrocatalytic activity of the mono (pyridine-4-oxy)-tri (tert-butyl) phthalocyaninato Co(II) (Pc1) and mono (pyridine-4-oxy)-hexa (hexyl) phthalocyaninato Co(II) (Pc2) are reported here. One reversi

Mechanism of the low-temperature interaction of hydrogen with α-oxygen on FeZSM-5 zeolite

Dubkov,Starokon',Paukshtis,Volodin,Panov

, p. 202 - 208 (2004)

The mechanism of a low-temperature reaction of hydrogen with the radical anion surface oxygen species (α-oxygen, Oα) formed by decomposing N2O over FeZSM-5 zeolite was studied using kinetic and isotope techniques. It was found that the reaction is of first order with respect to hydrogen and the rate of the reaction is proportional to the concentration of Oα. The activation energy of the reaction, which was measured for H2 or D2 over a temperature range from +20 to -100°C, is equal to 3.2 or 5.3 kcal/mol, respectively. The reaction occurs with a considerable kinetic isotope effect (kH/k D), which varies over the range of 3.4-41 depending on the temperature. This fact indicates that the rate-limiting step of the reaction includes the dissociation of the hydrogen molecule. The temperature dependence of the isotope effect gave a value of 2.1 kcal/mol, which is close to the difference between the zero bond energies in the molecules of H2 and D2; this fact suggests that a tunnel effect does not significantly contribute to the reaction. The dissociative mechanism is consistent with data obtained by in situ IR spectroscopy. The interaction of hydrogen with α-oxygen is accompanied by the formation of new hydroxyl groups O αH (absorption bands at 3635 and 3674 cm-1) at the surface of the zeolite. The identification of these groups was supported by an isotope shift either on the replacement of H2 by D2 or on the replacement of 16Oα by Oα,. The stoichiometric ratio H2:Oα, is consistent with the previously drawn conclusion on the paired arrangement of α-sites.

A four-electron O2-electroreduction biocatalyst superior to platinum and a biofuel cell operating at 0.88 V

Soukharev, Valentine,Mano, Nicolas,Heller, Adam

, p. 8368 - 8369 (2004)

O2 was electroreduced to water, at a true-surface-area-based current density of 0.5 mA cm-2, at 37 °C and at pH 5 on a wired laccase bioelectrocatalyst-coated carbon fiber cathode. The polarization (potential vs the reversible potential of the O2 /H2O half-cell in the same electrolyte) of the cathode was only -0.07 V, approximately one-fifth of the -0.37 V polarization of a smooth platinum fiber cathode, operating in its optimal electrolyte, 0.5 M H2SO4. The bioelectrocatalyst was formed by wiring laccase to carbon through an electron conducting redox hydrogel, its redox functions tethered through long and flexible spacers to its cross-linked and hydrated polymer. Incorporation of the tethers increased the apparent electron diffusion coefficient 100-fold to (7.6 ± 0.3) × 10-7 cm 2 s-1. A miniature single-compartment glucose-O2 biofuel cell made with the novel cathode operated optimally at 0.88 V, the highest operating voltage for a compartmentless miniature fuel cell. Copyright

2D Layered non-precious metal mesoporous electrocatalysts for enhanced oxygen reduction reaction

Huo, Lili,Liu, Baocang,Zhang, Geng,Si, Rui,Liu, Jian,Zhang, Jun

, p. 4868 - 4878 (2017)

Rational design of inexpensive, highly active, and long-term stable non-precious metal electrocatalysts for oxygen reduction reaction (ORR) is of significant importance for large-scale applications of fuel cells in practice. In this paper, we report, for the first time, the construction of 2D layered mesoporous transition metal-nitrogen-doped carbon/nitrogen-doped graphene (meso-M-N-C/N-G, M = Fe, Co, and Ni) electrocatalysts using 4,4-bipyridine as the nitrogen and carbon source and mesoporous KIT-6/N-G generated by in situ formation of KIT-6 on graphene nanosheets as a template. The meso-Fe-N-C/N-G electrocatalyst showed super electrocatalytic performance for ORR. Excitingly, its catalytic activity and durability were superior to those of Pt/C, making it a good candidate as an ORR electrocatalyst in fuel cells. The results suggested that the outstanding electrocatalytic performance of the electrocatalysts could be attributed to the unique mesoporous structure, high surface area, ultrasmall size of Fe or FeOx nanocrystals embedded in 2D layered N-G nanosheets, excellent electron transportation, homogeneous distribution of high-density pyridinic N and graphitic N, graphitic C, and abundant metal active sites (Fe-Nx). The synthesis approach can be used as a versatile route toward the construction of various 2D layered graphene-based mesoporous materials.

Rational Design of Hierarchical, Porous, Co-Supported, N-Doped Carbon Architectures as Electrocatalyst for Oxygen Reduction

Qiao, Mengfei,Wang, Ying,Mamat, Xamxikamar,Chen, Anran,Zou, Guoan,Li, Lei,Hu, Guangzhi,Zhang, Shusheng,Hu, Xun,Voiry, Damien

, p. 741 - 748 (2020)

Developing highly active nonprecious-metal catalysts for the oxygen reduction reaction (ORR) is of great significance for reducing the cost of fuel cells. 3D-ordered porous structures could substantially improve the performance of the catalysts because of their excellent mass-diffusion properties and high specific surface areas. Herein, ordered porous ZIF-67 was prepared by forced molding of a polystyrene template, and Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) was obtained after further carbonization. Co-NOPC exhibited excellent performance for the ORR in an alkaline medium with a half-wave potential of 0.86 V vs. reversible hydrogen electrode (RHE), which is higher than that of the state-of-the-art Pt/C (0.85 V vs. RHE). Moreover, the substantially improved catalytic performance of Co-NOPC compared with Co-supported, N-doped carbon revealed the key role of its hierarchical porosity in boosting the ORR. Co-NOPC also exhibited a close-to-ideal four-electron transfer path, long-term durability, and resistance to methanol penetration, which make it promising for large-scale application.

2H→1T Phase Engineering of Layered Tantalum Disulfides in Electrocatalysis: Oxygen Reduction Reaction

Luxa, Jan,Mazánek, Vlastimil,Pumera, Martin,Lazar, Petr,Sedmidubsky, David,Callisti, Mauro,Polcar, Tomá?,Sofer, Zdeněk

, p. 8082 - 8091 (2017)

Tremendous attention is currently being paid to renewable sources of energy. Transition-metal dichalcogenides (TMDs) have been intensively studied for their promising catalytic activities in the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR). In this fundamental work, we explored the catalytic properties of TMD family members 2H TaS2 and 1T TaS2. Our findings reveal that both polytypes exhibit poor HER performance, which is even more pronounced after electrochemical reduction/oxidation. Our experimental data show that 1T TaS2 has a lower overpotential at a current density of ?10 mA cm?1, despite theoretical DFT calculations that indicated that the more favorable free energy of hydrogen adsorption should make “perfect” 2H TaS2 a better HER catalyst. Thorough characterization showed that the higher conductivity of 1T TaS2 and a slightly higher surface oxidation of 2H TaS2 explains this discrepancy. Moreover, changes in the catalytic activity after electrochemical treatment are addressed here. For the ORR in an alkaline environment, the electrochemical treatment led to an improvement in catalytic properties. With onset potentials similar to that of Pt/C catalysts, TaS2 was found to be an efficient catalyst for the ORR, rather than for proton reduction, in contrast to the behavior of Group 6 layered TMDs.

Bifunctional gold-manganese oxide nanocomposites: Benign electrocatalysts toward water oxidation and oxygen reduction

Rahaman, Hasimur,Barman, Koushik,Jasimuddin, Sk,Ghosh, Sujit Kumar

, p. 41976 - 41981 (2014)

Gold-manganese oxide nanocomposites were synthesised by seed-mediated epitaxial growth at the water/n-heptane interface under mild reflux conditions. These nanocomposites exhibit efficient electrocatalytic activity toward the water oxidation reaction (WOR) and the simultaneous oxygen reduction reaction (ORR) at a low overpotential (η ≈ 370 mV) and under neutral pH conditions. This journal is

Boosting the catalysis of AuCuMo for oxygen reduction: Important roles of an optimized electronic structure and surface electrochemical stability

Gong, Hongyu,Li, Fan,Li, Ling,Yang, Bo,Yang, Ruizhi

, (2020)

The slow kinetics of the oxygen reduction reaction (ORR) remains a great challenge in many energy storage and conversion devices, such as alkaline fuel cells and metal-air batteries. Herein, a self-supported Au-based alloy (AuCuMo) was successfully synthesized by a one-pot hydrothermal method. By combining Cu and Mo, the electronic structure of Au was finely tuned. Furthermore, the electrochemical stability of surface Cu was enhanced by the incorporation of Mo. Benefitting from these advantages, the reaction of oxygen and oxygenated intermediates on AuCuMo was optimized, and the intrinsic activity was improved. AuCuMo thereby exhibited superior ORR activity and stability compared to commercial Pt/C catalysts.

Kinetic characterization of the reduction of silica supported cobalt catalysts

Wan,Li,Chen

, p. 415 - 419 (2007)

The reduction process of silica supported cobalt catalyst was studied by thermal analysis technique. The reduction of the catalyst proceeds in two steps: Co3O4 + H2 to 3CoO + H2O, 3CoO + 3H2 to 3Co + 3H2O which was validated by the TPR and in-situ XRD experiments. The kinetic parameters of the reduction process were obtained with a comparative method. For the first step, the activation energy, E a, and the pre-exponential factor, A, were found to be 104.35 kJ mol-1 and 1.18?106~2.45?109 s-1 respectively. The kinetic model was random nucleation and growth and the most probable mechanism function was found to be f(α)=3/2(1- α)[-ln(1-α)]1/3 or in the integral form: g(α)=[-ln(1-α)]2/3. For the second step, the activation energy, E a, and the pre-exponential factor, A, were found to be 118.20 kJ mol-1 and 1.75?107~2.45 ? 10 9s-1 respectively. The kinetic model was a second order reaction and the probable mechanism function was f(α)=(1-α) 2 or in the integral form: g(α)=[1-α]-1-1.

Effect of the Composition of Supported Copper-Containing Salt Catalysts on Their Activity in the Deacon Reaction: Dependence of the Rate of the Deacon Reaction on the Ratio between Copper and Potassium Chlorides in a Supported CuCl2–KCl Salt Catalyst

Aglulin

, p. 290 - 296 (2019)

Abstract: The effect of KCl/CuCl2 molar ratios from 0 to 2.5 in the СuCl2–KCl catalyst (support) on its activity in the Deacon reaction was studied by a gradientless method in a temperature range of 350–425°C. The essential role of the hydration processes of the salt catalyst components in the homogenization of a reaction layer was established. The experiments did not contradict the previously proposed reaction kinetics and mechanism. A possible explanation of the experimental results was given based on the polarization representations used earlier in the reaction mechanism.

Enhanced oxygen reduction activity of platinum subnanocluster catalysts through charge redistribution

Tsunoyama, Hironori,Ohnuma, Akira,Takahashi, Koki,Velloth, Archana,Ehara, Masahiro,Ichikuni, Nobuyuki,Tabuchi, Masao,Nakajima, Atsushi

, p. 12603 - 12606 (2019)

Single-size platinum Pt6 subnanoclusters exhibit superior mass-specific and surface-specific activities for the oxygen reduction reaction. The enhanced activity is attributed to polarized electron distributions based on rigorous structure chara

Core-Shell Nanocomposites Based on Gold Nanoparticle@Zinc-Iron-Embedded Porous Carbons Derived from Metal-Organic Frameworks as Efficient Dual Catalysts for Oxygen Reduction and Hydrogen Evolution Reactions

Lu, Jia,Zhou, Weijia,Wang, Likai,Jia, Jin,Ke, Yunting,Yang, Linjing,Zhou, Kai,Liu, Xiaojun,Tang, Zhenghua,Li, Ligui,Chen, Shaowei

, p. 1045 - 1053 (2016)

Core-shell nanocomposites based on Au nanoparticle@zinc-iron-embedded porous carbons (Au@Zn-Fe-C) derived from metal-organic frameworks were prepared as bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). A single Au nanoparticle of 50-100 nm in diameter was encapsulated within a porous carbon shell embedded with Zn-Fe compounds. The resulting Au@Zn-Fe-C hybrids exhibited apparent catalytic activity for ORR in 0.1 M KOH (with an onset potential of +0.94 V vs RHE, excellent stability and methanol tolerance) and for HER as well, which was evidenced by a low onset potential of -0.08 V vs RHE and a stable current density of 10 mA cm-2 at only -0.123 V vs RHE in 0.5 M H2SO4. The encapsulated Au nanoparticles played an important role in determining the electrocatalytic activity for ORR and HER by promoting electron transfer to the zinc-iron-embedded porous carbon layer, and the electrocatalytic activity was found to vary with both the loading of the gold nanoparticle cores and the thickness of the metal-carbon shells. The experimental results suggested that metal-embedded porous carbons derived from metal-organic frameworks might be viable alternative catalysts for both ORR and HER.

Taube, H.

, p. 2468 - 2474 (1942)

Factors affecting catalytic destruction of H2O2 by hydrogenation and decomposition over Pd catalysts supported on activated carbon cloth (ACC)

Gudarzi, Davood,Ratchananusorn, Warin,Turunen, Ilkka,Heinonen, Markku,Salmi, Tapio

, p. 69 - 79 (2015)

Destruction of hydrogen peroxide by its decomposition and hydrogenation over Pd catalysts supported on activated carbon cloth has been investigated. The catalysts were prepared by the impregnation method using acidic solution of palladium dichloride (PdCl2) as a metal precursor. The reactions were performed batchwise in a Parr stainless steel autoclave. Tests were run at room temperature using either methanol or water as a reaction medium. The effects of oxidation pre-treatment of the support with different acids (nitric and acetic acid), the heat treatment of the catalysts in different atmospheres (H2 and air), and Pd content on the final properties and H2O2 destruction activity of the catalysts were investigated. The results indicated that oxygen-containing surface functional groups have an important role in determining the physicochemical properties and H2O2 destruction activity of the catalysts. In fact, the presence of these groups stabilizes H2O2 in the solution and reduces its decomposition and hydrogenation. Furthermore, the presence of the oxidized state of Pd (PdO) in the catalyst makes it less active in H2O2 decomposition when compared to the corresponding zero valences (Pd0) catalyst. Using water instead of methanol dramatically increased the H2O2 decomposition

Keck, K.-E.,Kasemo, B.,Hoegberg, T.

, p. 469 - 478 (1983)

Tungsten oxide in polymer electrolyte fuel cell electrodes - A thin-film model electrode study

Wickman, Bj?rn,Wesselmark, Maria,Lagergren, Carina,Lindbergh, G?ran

, p. 9496 - 9503 (2011)

Thin films of WOx and Pt on WOx were evaporated onto the microporous layer of a gas diffusion layer (GDL) and served as model electrodes in the polymer electrolyte fuel cell (PEFC) as well as in liquid electrolyte measurements. In order to study the effects of introducing WO x in PEFC electrodes, precise amounts of WOx (films ranging from 0 to 40 nm) with or without a top layer of Pt (3 nm) were prepared. The structure of the thin-film model electrodes was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy prior to the electrochemical investigations. The electrodes were analyzed by cyclic voltammetry and the electrocatalytic activity for hydrogen oxidation reaction (HOR) and CO oxidation was examined. The impact of Nafion in the electrode structure was examined by comparing samples with and without Nafion solution sprayed onto the electrode. Fuel cell measurements showed an increased amount of hydrogen tungsten bronzes formed for increasing WOx thicknesses and that Pt affected the intercalation/deintercalation process, but not the total amount of bronzes. The oxidation of pre-adsorbed CO was shifted to lower potentials for WOx containing electrodes, suggesting that Pt-WO x is a more CO-tolerant catalyst than Pt. For the HOR, Pt on thicker films of WOx showed an increased limiting current, most likely originating from the increased electrochemically active surface area due to proton conductivity and hydrogen permeability in the WOx film. From measurements in liquid electrolyte it was seen that the system behaved very differently compared to the fuel cell measurements. This exemplifies the large differences between the liquid electrolyte and fuel cell systems. The thin-film model electrodes are shown to be a very useful tool to study the effects of introducing new materials in the PEFC catalysts. The fact that a variety of different measurements can be performed with the same electrode structure is a particular strength.

Kinetics and Mechanism of the OH + HO2 Reaction

Schwab, James J.,Brune, William H.,Anderson, James G.

, p. 1030 - 1035 (1989)

A discharge flow reactor with laser magnetic resonance and resonance fluorescence detection axes is used to measure the rate constant for the raction of OH and HO2 radicals by measuring the decay of OH in excess HO2 under pseudo-first-order conditions.Particular care is taken to reduce impurity O and H atoms to low levels since their presence leads to an underestimate of the rate constant.The rate constant is measured to be (8.0 +3.0/-2.0) x 1E-11 cm3 molecule-1 s-1 at 298 K and 2 Torr after a small (3 percent) correction is made for the impurity atoms.It is argued that recent experimental and theoretical results indicate that the reaction mechanism is likely dominated by attack at the hydrogen and of HO2 and that the reaction is unusually fast due a long-range attractive interaction.

Absolute Rate Constant of the Reaction OH + H2O2 -> HO2 + H2O from 245 to 423 K

Keyser, L. F.

, p. 1659 - 1663 (1980)

The absolute rate constant of the reaction between the hydroxyl radical and hydrogen peroxide was measured by using the discharge-flow resonance fluorescence technique at total pressures between 1 and 4 torr.At 298 K the results is (1.64+/-0.32)E-12 cmsu

Significantly improved electrocatalytic oxygen reduction by an asymmetrical Pacman dinuclear cobalt(ii) porphyrin-porphyrin dyad

Liu, Yanju,Zhou, Guojun,Zhang, Zongyao,Lei, Haitao,Yao, Zhen,Li, Jianfeng,Lin, Jun,Cao, Rui

, p. 87 - 96 (2020)

Pacman dinuclear CoII triphenylporphyrin-tri(pentafluorophenyl)porphyrin 1 and dinuclear CoII bis-tri(pentafluorophenyl)porphyrin 2, anchored at the two meso-positions of a benzene linker, are synthesized and examined as electrocatalysts for the oxygen reduction reaction (ORR). Both dinuclear Co bisporphyrins are more efficient and selective than corresponding mononuclear CoII tetra(pentafluorophenyl)porphyrin 3 and CoII tetraphenylporphyrin 4 for the four-electron electrocatalytic reduction of O2 to water. Significantly, although the ORR selectivities of the two dinuclear Co bisporphyrins are similar to each other, 1 outperforms 2, in terms of larger catalytic ORR currents and lower overpotentials. Electrochemical studies showed different redox behaviors of the two Co sites of 1: the CoIII/CoII reduction of the Co-TPP (TPP = triphenylporphyrin) site is well-behind that of the Co-TPFP (TPFP = tri(pentafluorophenyl)porphyrin) site by 440 mV. This difference indicated their different roles in the ORR: CoII-TPFP is likely the O2 binding and reduction site, while CoIII-TPP, which is generated by the oxidation of CoII-TPP on electrodes, may function as a Lewis acid to assist the O2 binding and activation. The positively charged CoIII-TPP will have through-space charge interactions with the negatively charged O2-adduct unit, which will reduce the activation energy barrier for the ORR. This effect of Co-TPP closely resembles that of the CuB site of metalloenzyme cytochrome c oxidase (CcO), which catalyzes the biological reduction of O2. This work represents a rare example of asymmetrical dinuclear metal catalysts, which can catalyze the 4e reduction of O2 with high selectivity and significantly improved activity.

Nitrogen/sulfur co-doped non-noble metal material as an efficient electrocatalyst for the oxygen reduction reaction in alkaline media

Xu, Li,Pan, Guoshun,Liang, Xiaolu

, p. 19756 - 19765 (2014)

This work demonstrates the feasibility of nitrogen/sulfur co-doped non-noble metal materials (Fe-N/C-TsOH) as platinum-free catalysts for the oxygen reduction reaction (ORR) in alkaline media. Electrochemical techniques such as cyclic voltammetry (CV), rotating disk electrodes (RDEs) and rotating ring-disk electrodes (RRDEs) are employed with the Koutecky-Levich theory to investigate the ORR kinetic constants and the reaction mechanism. It is found that the catalysts doped with TsOH (p-toluenesulfonic acid) show significantly improved ORR activity relative to a TsOH-free catalyst. The overall electron transfer numbers for the catalyzed ORR are determined to be 3.899 and 3.098, respectively, for the catalysts with and without TsOH-doping. Catalysts heat treated at 600 °C exhibit relatively higher activity. In addition, the catalyst doped with TsOH (Fe-N/C-TsOH-600) not only exhibits exceptional stability in 0.1 mol L-1 KOH solution but also has higher methanol tolerance compared to commercial Pt/C catalyst in 0.1 mol L-1 KOH. To some extent, increasing the Fe-N/C-TsOH-600 loading on the electrode favors a faster reduction of H2O2 to intermediate to H 2O. X-ray photoelectron spectroscopy analysis indicates that pyrrolic N groups are the most active sites, and that sulfur species are structurally bound to carbon in the forms of C-S(n)-C and oxidized -SO (n)- bonds, an additional beneficial factor for the ORR.

Covalent Phenanthroline Framework Derived FeS@Fe3C Composite Nanoparticles Embedding in N-S-Codoped Carbons as Highly Efficient Trifunctional Electrocatalysts

Kong, Fantao,Fan, Xiaohong,Kong, Aiguo,Zhou, Ziqian,Zhang, Xiaoying,Shan, Yongkui

, (2018)

Efficient and earth-abundant materials with multifunctional electrocatalytic properties within a wide range of pH are the new darlings for developing green energy conversion and storage techniques. A novel porous covalent phenanthroline framework (Fe-Phen-COFs) that involved Fe-DMSO (dimethyl sulfoxide) coordination complexes is successfully synthesized using 3, 8-dibromophenanthroline and 1, 3, 5-benzenetriboronicacid trivalent alcohol ester as a rigid building block via Suzuki coupling reaction. Fe-Phen-COFs as the self-carrier enriched with Fe, S, N, and C is pyrolyzed to produce N-S-codoping carbons with embedded core–shell Fe3C and FeS composite nanostructures (FeS/Fe3C@N-S-C). The FeS/Fe3C@N-S-C-800 obtained by pyrolysis at 800 °C exhibits efficient trifunctional electrocatalytic activity for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) within a wide pH range. Impressively, the ORR half-potential of FeS/Fe3C@N-S-C-800 reaches 0.87 V in 0.1 m KOH, more positive than the previously reported Pt-free electrocatalysts. It could be utilized as the advanced air electrode materials in zinc–air batteries, which exhibit an excellent power density and cycling stability superior to those of Pt/C-based zinc–air battery. Thermal conversion of novel Fe-Phen-COFs provides an effective strategy to prepare high-performance trifunctional electrocatalytic materials for the new-generation powerful energy conversion technologies.

Nelson, H. H.,Marinelli, W. J.,Johnston, H. S.

, p. 495 - 499 (1981)

Griffith, R. O.,Shutt, W. J.

, p. 2752 - 2767 (1923)

In situ growth of Pt3Ni nanoparticles on an A-site deficient perovskite with enhanced activity for the oxygen reduction reaction

Gao, Yang,Wang, Jian,Lyu, Yu-Qi,Lam, Kwunyu,Ciucci, Francesco

, p. 6399 - 6404 (2017)

A novel A-site deficient perovskite, La0.9Mn0.9Pt0.075Ni0.025O3-δ, is developed as a catalyst for the oxygen reduction reaction in alkaline solution. Pt3Ni nanoparticles are exsolved in situ on the surface upon reduction. The catalytic activity improves significantly after exsolution. This improvement is attributed to the synergy between the host perovskite and the nanoparticles.

Accelerating the oxygen reduction reaction via a bioinspired carbon-supported zinc electrocatalyst

Nahavandi, Faezeh,Seyyedi, Behnam

, p. 291 - 296 (2019)

Oxygen utilization in electrochemical energy generation systems requires to overcome the slow kinetics of oxygen reduction reaction (ORR). Herein, we have outstretched an efficient strategy in order for developing a bioinspired Zn (N4)/sulfur/graphitic carbon composite (Zn-S-Gc) with an effective performance for the ORR at low temperature. The catalyst composite was created by attaching the Zn (N4) centers in the form of zinc phthalocyanine on the sulfur-linked graphitic carbon surface. The most positive ORR onset potential of about 1.00 V versus a reversible hydrogen electrode (RHE) was obtained due to the unique structure of a new catalyst in KOH solution (pH = 13) at low temperature (T = 298 K). The catalyst was evaluated using the rotating-disk electrode method in the potential range of ?0.02–1.18 V versus RHE. The number of transferred electrons as one of the most important parameters (n > 3.70) is almost constant in a wide range of low overpotentials (0.1–0.6 V), which indicates a more efficient four-electron pathway from O2 to H2O on the catalyst surface. The estimated Tafel slope in an appropriate range is about ≈ ?133.3 mV/dec at a low current density and E1/2 of the electrocatalyst displays a negative shift of only 11 mV after 10,000 cycles. The mean size of the catalyst centers is on the nanoscale (50 nm).

Water affects the stereochemistry and dioxygen reactivity of carboxylate-rich diiron(II) models for the diiron centers in dioxygen-dependent non-heme enzymes

Yoon, Sungho,Lippard, Stephen J.

, p. 8386 - 8397 (2005)

Carboxylate-bridged high-spin diiron(II) complexes with distinctive electronic transitions were prepared by using 4-cyanopyridine (4-NCC 5H4N) ligands to shift the charge-transfer bands to the visible region of the absorption spectrum. This property facilitated quantitation of water-dependent equilibria in the carboxylate-rich diiron(II) complex, [Fe2(μ-O2CArTol) 4(4-NCC5H4N)2] (1), where -O2CArTol is 2,6-di-(p-tolyl)benzoate. Addition of water to 1 reversibly shifts two of the bridging carboxylate ligands to chelating terminal coordination positions, converting the structure from a paddlewheel to a windmill geometry and generating [Fe2(μ-O 2CArTol)2(O2CArTol) 2(4-NCC5H4N)2(H2O) 2] (3). This process is temperature dependent in solution, rendering the system thermochromic. Quantitative treatment of the temperature-dependent spectroscopic changes over the temperature range from 188 to 298 K in CH 2Cl2 afforded thermodynamic parameters for the interconversion of 1 and 3. Stopped flow kinetic studies revealed that water reacts with the diiron(II) center ca. 1000 time faster than dioxygen and that the water-containing diiron(II) complex reacts with dioxygen ca. 10 times faster than anhydrous analogue 1. Addition of {H(OEt2)2} {BAr′4}, where BAr′4- is tetrakis(3,5- di(trifluoromethyl)phenyl)borate, to 1 converts it to [Fe2(μ- O2CArTol)3(4-NCC5H 4N)2]-(BAr′4) (5), which was also structurally characterized. Moessbauer spectroscopic investigations of solid samples of 1, 3, and 5, in conjunction with several literature values for high-spin iron(II) complexes in an oxygen-rich coordination environment, establish a correlation between isomer shift, coordination number, and N/O composition. The products of oxygenating 1 in CH2Cl2 were identified crystallographically to be [Fe2(μ-OH) 2(μ-O2CArTol)2(O 2CArTol)2(4-NCC5H4N) 2]·2(HO2CArTol) (6) and [Fe 6(μ-O)2(μ-OH)4(μ-O2CAr Tol)6(4-NCC5H4N)4Cl 2] (7).

Direct NMR and luminescence observation of water exchange at cationic ytterbium and europium centres

Batsanov, Andrei S.,Beeby, Andrew,Bruce, James I.,Howard, Judith A. K.,Kenwright, Alan M.,Parker, David

, p. 1011 - 1012 (1999)

Cationic chiral Yb and Eu tetra-amide complexes, have been studied by VT NMR, luminescence and crystallography: the rate of dissociation of water is about 500 times faster at Yb than at the square antiprismatic Eu centre.

Giauque, W. F.,Johnston, H. L.

, p. 2300 - 2321 (1929)

The influence of ruthenium substitution in LaCoO3towards bi-functional electrocatalytic activity for rechargeable Zn-air batteries

Caruso, Rachel A.,Chandrappa, Shivaraju Guddehalli,Chen, Dehong,Karkera, Guruprakash,Moni, Prabu,Prakash, Annigere S.,Prakasha, Kunkanadu R.

, p. 20612 - 20620 (2020)

The rechargeable zinc-air battery is a clean technology for energy storage applications but is impeded by the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during its cycling. Herein, a series of lanthanum cobaltate based perovskites are synthesised with the B-site cation deficiencies in the structure occupied by Ru substitution: LaCo1-xRuxO3-δ (x = 0, 0.1, 0.2, 0.3 and 0.5). These compositions were designed to enhance the OER/ORR activities, which are two vital reactions for rechargeable Zn-air batteries. Powder X-ray diffraction analysis revealed that increasing the Ru substitution >20% (x > 0.2) alters the LaCoO3 crystal structure from rhombohedral to orthorhombic. Photoelectron spectroscopy studies reveal that the surface oxygen vacancies increased in the Ru substituted catalyst, a property important for enhancing the OER/ORR efficiency. The LaCo0.8Ru0.2O3-δ (LCRO82) catalyst exhibits promising electrocatalytic activities in both the OER and the ORR in 0.1 M KOH solution. Furthermore, the LCRO82 catalyst was evaluated as a cathode for rechargeable Zn-air battery applications displaying a high power density of 136 mW cm-2 at a current density of 175 mA cm-2 and a stable charge-discharge voltage gap of 0.78 V after 1440 cycles, with excellent cycling stability over 240 h.

Accelerated diffusion of chain carriers and kinetic features of heterogeneous processes in gas-phase chain reactions

Azatyan,Piloyan,Baimuratova,Masalova

, p. 178 - 185 (2008)

In gas-phase combustion processes, the regeneration of free atoms and radicals in chain propagation reactions enhances the diffusion flux of these species from the flame zone. In flame propagation in tubular reactors and in filtration combustion, this eff

Electroreduction of O2 to water on the wired laccase cathode

Barton, Scott Calabrese,Kim, Hyug-Han,Binyamin, Gary,Zhang, Yongchao,Heller, Adam

, p. 11917 - 11921 (2001)

Oxygen was electrocatalytically reduced to water at a current density of 5 mA/cm2 and at +0.7 V (NHE) in pH 5 citrate buffer at 37.5 ?°C. The electrocatalyst was a composite of laccase cross-linked with a redox polymer on a hydrophilic cloth of 10 ??m diameter carbon fibers. The redox polymer, PVI-Os(tpy)(dme-bpy)2+/3+, [poly-N-vinyl imidazole with 1/5th of the imidazoles complexed with [Os(tpy)(dme-bpy)]2+/3+ (tpy=terpyridine; dme-bpy= 4,4a?2-dimethyl-2,2a?2-bipyridine)], electrically connected ( wired ) the laccase reaction centers to the fibers.

Oxygen Reduction Catalysis at a Dicobalt Center: The Relationship of Faradaic Efficiency to Overpotential

Passard, Guillaume,Ullman, Andrew M.,Brodsky, Casey N.,Nocera, Daniel G.

, p. 2925 - 2928 (2016)

The selective four electron, four proton, electrochemical reduction of O2 to H2O in the presence of a strong acid (TFA) is catalyzed at a dicobalt center. The faradaic efficiency of the oxygen reduction reaction (ORR) is furnished from a systematic electrochemical study by using rotating ring disk electrode (RRDE) methods over a wide potential range. We derive a thermodynamic cycle that gives access to the standard potential of O2 reduction to H2O in organic solvents, taking into account the presence of an exogenous proton donor. The difference in ORR selectivity for H2O vs H2O2 depends on the thermodynamic standard potential as dictated by the pKa of the proton donor. The model is general and rationalizes the faradaic efficiencies reported for many ORR catalytic systems.

Functional Species Encapsulated in Nitrogen-Doped Porous Carbon as a Highly Efficient Catalyst for the Oxygen Reduction Reaction

Song, Li,Wang, Tao,Ma, Yiou,Xue, Hairong,Guo, Hu,Fan, Xiaoli,Xia, Wei,Gong, Hao,He, Jianping

, p. 3398 - 3405 (2017)

The scarcity, high cost, and poor stability of precious metal-based electrocatalysts have stimulated the development of novel non-precious metal catalysts for the oxygen reduction reaction (ORR) for use in fuel cells and metal–air batteries. Here, we fabricated in situ a hybrid material (Co-W-C/N) with functional species (tungsten carbide and cobalt nanoparticles) encapsulated in an N-doped porous carbon framework, through a facile multi-constituent co-assembly method combined with subsequent annealing treatment. The unique structure favors the anchoring active nanoparticles and facilitates mass transfer steps. The homogenously distributed carbide nanoparticles and adjacent Co-N-C sites lead to the electrocatalytic synergism for the ORR. The existence of Co and W can promote the graphitization of the carbon matrix. Benefiting from its structural and material superiority, the Co-W-C/N electrocatalyst exhibits excellent electrocatalytic activity (with a half-wave potential of 0.774 V vs. reversible hydrogen electrode (RHE)), high stability (96.3 % of the initial current remaining after 9000 s of continuous operation), and good immunity against methanol in alkaline media.

Tannic acid decorated AuPd lavender-like nanochains for enhanced oxygen reduction electrocatalysis

Jiao, Shiqian,Li, Xiaonian,Liu, Songliang,Wang, Hongjing,Wang, Liang,Wang, Ziqiang,Xu, You,Yin, Shuli,Zhang, Hugang

, p. 15678 - 15683 (2021)

Benefiting from the interaction of inorganic and organic building blocks, the design of metal-organic nanohybrids is of great significance for the oxygen reduction reaction (ORR). Herein, a universal strategy is presented to controllably synthesize tannic acid (TA) functionalized AuPd lavender-like nanochains (AuPd@TA LCs) by a chemical reduction method at low temperature. Due to the unique structural characteristics and polyphenolic modification, the AuPd@TA LCs show superior ORR performance in an alkaline electrolyte. Moreover, the surface decorated TA polymers can act as a molecular screen window to prevent methanol molecules from accessing the active site of the catalyst, thus resulting in high methanol tolerance and catalytic stability. The presented molecular screen window strategy is highly valuable for designing ORR electrocatalysts with high methanol tolerance.

Nitrogen-doped graphene supported cobalt oxide nanocomposite as high performance electrocatalyst for oxygen reduction reaction

Yasmin, Sabina,Ahmed, Mohammad Shamsuddin,Jeon, Seungwon

, p. 3959 - 3966 (2017)

Nitrogen doped reduced graphene oxide-supported cobalt oxide catalyst has been synthesized by a simple one step chemical reduction method (denoted as NrGO-Co3O4) for electrocatalytic oxygen reduction reaction (ORR). This material has been characterized by various instrumental methods. The morphological analysis shows the Co3O4 nanocomposites are well set on to the reduced graphene oxide with better dispersion. The X-ray photoelectron spectroscopy (XPS) shows electrochemical reduction has been done successfully with the increasing C/O ratio. Also, the Raman data reveals that the Co is presents with the oxidized form. The electrocatalytic activities have been verified using cyclic voltammetry (CV) and hydrodynamic voltammetry techniques in 0.1 M KOH electrolyte. The as prepared catalyst has shown more positively shifted onset and half wave potential (-0.091 V and -0.276 vs. Ag/AgCl) and high cathodic current density 2.57 mA cm-2 and high methanol, ethanol crossover tolerance than Pt/C. It is the introduction of strongly bonded cobalt nanocomposite into the network of NrGO that modulate the electronic properties of the NrGO-Co3O4, resulting in the superb electrocatalytic performance. The reaction kinetics have confirmed that the ORR at NrGO-Co3O4 catalyst follows a four electron transfer reaction process.

Fe ultra-small particles anchored on carbon aerogels to enhance the oxygen reduction reaction in Zn-air batteries

Shi, Jinjin,Shu, Xinxin,Xiang, Chensheng,Li, Hong,Li, Yang,Du, Wei,An, Pengfei,Tian, He,Zhang, Jintao,Xia, Haibing

, p. 6861 - 6871 (2021)

In this work, ultra-small Fe particles (Fe-UPs) anchored on carbon aerogel (CA) (Fe-UP/CA catalysts) are successfully prepared by the optimal pyrolysis of hollow composite particles of zeolitic imidazolate framework-8 (ZIF) coated with coordination complexes of tannic acid (TA) and Fe precursors. Within these Fe-UPs, each Fe-N4moiety is separated by one O atom while each Fe atom is coordinated with four N atoms and one O atom. The as-prepared Fe-UPs composed of the Fe-N4-O-Fe-N4moiety (FeFe-O-Fe-UPs) are proposed as a new type of active species for the first time, to the best of our knowledge. Moreover, different types of active species (such as Fe single atoms, FeFe-O-Fe-UPs, and Fe nanoparticles) in the CA can be controlled by rationally adjusting the Fe-to-TA molar ratios. More importantly, FeFe-O-Fe-UPs in Fe-UP/CA catalysts are realized at an Fe-to-TA molar ratio of 2.2. With the merits of both Fe-single atom and traditional Fe-NPs, the as-prepared FeFe-O-Fe-UP/CA catalysts are able to regulate properly the adsorption of reactants and the desorption of intermediates and products due to their increasing size and the presence of the multi-metal-atom structure. Accordingly, the as-prepared FeFe-O-Fe-UP/CA catalysts towards the oxygen reduction reaction (ORR) exhibit a higher half-wave potential (0.93 Vvs.0.89 V of Pt/C), a higher onset potential (1.08 Vvs.1.0 V of Pt/C), a higher kinetic current density (14.2 mA cm?2at 0.9 V) and better long-term stability in alkaline media. Additionally, Zn-air batteries assembled with such electrocatalysts also exhibit a higher power density of 140.1 mW cm?2and a larger specific capacity of 781.7 mA h g?1, which are better than those of the state-of-the-art the commercial Pt/C catalyst.

Four-electron reduction of dioxygen catalyzed by a decavanadium complex

Dewi, Eniya Listiani,Oyaizu, Kenichi,Tsuchida, Eishun

, p. 316 - 318 (2003)

The electroreduction of O2 in acidic aqueous solutions at an electrode modified with a decavanadium cluster [(V=O)10(μ2-O)9(μ3-O) 3(C5H7O2)6] (1) revealed that it produces H2O with four electrons per O2 molecule near 0.5 V versus SCE. The usefulness of the complex as a reduction catalyst of O2 with a high selectivity was demonstrated.

Hill, G. R.

, p. 1306 - 1307 (1948)

Synergetic Metals on Carbocatalyst Shungite

Gusm?o, Rui,Sofer, Zdeněk,Bou?a, Daniel,Pumera, Martin

, p. 18232 - 18238 (2017)

The naturally occurring Palaeoproterozoic carbon mineral shungite is a complex raw carbon microporous matrix, loaded with a wide range of elements. Shungite exhibits a disordered and amorphous structure with highly irregular building blocks. Shungite incorporates metals in its structure; typically catalytic elements such Fe and Ni are present, as well as the toxic elements Pb and As at mg g?1 levels. We show here that incorporation of the metals in the carbon matrix of shungite leads into synergistic catalytic effect. We investigate the application of shungite in energy related electrochemical catalytic reactions, such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). All elements have a synergetic effect, thus contributing for shungite′s interesting catalytic performance towards a different range of electrochemical reactions, outperforming other tested carbon allotropes, such as carbon black, metal loaded carbon nanotubes, fullerene, and glassy carbon. These findings have profound impact on the application of the natural carbon materials for catalysis.

Facile synthesis of well dispersed spinel cobalt manganese oxides microsphere as efficient bi-functional electrocatalysts for oxygen reduction reaction and oxygen evolution reaction

Yang, Shuting,Wang, Zhichao,Cao, Zhaoxia,Mao, Xinxin,Shi, Mengjiao,Li, Yanlei,Zhang, Ruirui,Yin, Yanhong

, p. 482 - 491 (2017)

Developing catalysts with high bi-functional electrocatalytic activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for the fuel cells and metal-air batteries because of the sluggish kinetics of oxygen electrochemical reaction. Herein, we prepared a porous and well dispersed spinel MnCo2O4 (MCO) catalyst through a facile solvothermal method followed by a calcination process. CH3COONH4 used in solvothermal process played an important role in control of the size and morphology of MCO. The as-prepared MCO submicrospheres feature a porous structure and a high specific surface area. Tested by the rotating ring disk electrode (RRDE) technique, the sample MCO-10 and MCO-5 shows best catalytic towards ORR and OER, respectively. In particular, MCO-10 exhibits a high diffusion limiting current density (5 mA cm?2) and a better stability comparable to commercial Pt/C (20 wt% Pt on carbon) catalyst.

Makower, B.

, p. 1315 - 1319 (1934)

Wahnstroem, T.,Ljungstroem, S.,Rosen, A.,Kasemo, B.

, p. 439 - 451 (1990)

Designed nanostructured Pt film for electrocatalytic activities by underpotential deposition combined chemical replacement techniques

Huang, Minghua,Jin, Yongdong,Jiang, Heqing,Sun, Xuping,Chen, Hongjun,Liu, Baifeng,Wang, Erkang,Dong, Shaojun

, p. 15264 - 15271 (2005)

Multiple-deposited Pt overlayer modified Pt nanoparticle (MD-Pt overlayer/PtNPs) films were deliberately constructed on glassy carbon electrodes through alternately multiple underpotential deposition (UPD) of Ag followed redox replacement reaction by Pt (II) cations. The linear and regular growth of the films characterized by cyclic voltammetry was observed. Atomic force spectroscopy (AFM) provides the surface morphology of the nanostructured Pt films. Rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry demonstrate that the MD-Pt overlayer/PtNPs films can catalyze an almost four-electron reduction of O2 to H 2O in air-saturated 0.1 M H2SO4. Thus-prepared Pt films behave as novel nanostructured electrocatalysts for dioxygen reduction and hydrogen evolution reaction (HER) with enhanced electrocatalytic activities, in terms of both reduction peak potential and peak current, when compared to that of the bulk polycrystalline Pt electrode. Additionally, it is noted that after multiple replacement cycles, the electrocatalytic activities improved remarkably, although the increased amount of Pt is very low in comparison to that of pre-modified PtNPs due to the intrinsic feature of the UPD-redox replacement technique. In other words, the electrocatalytic activities could be improved markedly without using very much Pt by the technique of tailoring the catalytic surface. These features may provide an interesting way to produce Pt catalysts with a reliable catalytic performance as well as a reduction in cost. ? 2005 American Chemical Society.

Frost, A. A.,Oldenberg, O.

, p. 781 - 784 (1936)

Rock-Salt-Type MnCo2O3/C as Efficient Oxygen Reduction Electrocatalysts for Alkaline Fuel Cells

Yang, Yao,Zeng, Rui,Xiong, Yin,Disalvo, Francis J.,Abru?a, Héctor D.

, p. 9331 - 9337 (2019)

The search for nonprecious metal-based electrocatalysts with high activity and long durability for the oxygen reduction reaction (ORR) has been long pursued by the renewable energy material community. Here, we designed a new Mn-Co bimetallic oxide MnCo2O3/C with the rock-salt-type structure, derived from a spinel-type precursor MnCo2O4/C under mild reduction using NH3 at 300 °C. In-depth electron microscopic and spectroscopic investigations suggest that MnCo2O3/C predominantly has Mn(II) and Co(II) and can be written as MnO(CoO)2/C. Charge transfer between Mn and Co was probed by electron energy-loss near-edge structure (ELNES) analysis. MnCo2O3/C has a Co-rich core and a thin 1-3 nm Mn shell with a mesoporous morphology. MnCo2O3/C achieved a high ORR activity with a half-wave potential of 0.86 V in 1 M KOH, which was ascribed to the microstructure and the synergistic effects between Mn and Co, serving as co-active sites for the ORR.

Facile preparation of porous hollow CoxMn3-xO4 normal-reverse coexisted spinel for toluene oxidation

Gu, Wenxiu,Li, Chenqi,Qiu, Jianhao,Yao, Jianfeng

, (2021/10/08)

A facile method for the preparation of porous hollow CoxMn3-xO4 normal-reverse coexisted spinel is developed. The CoxMn3-xO4 catalysts with different morphologies can be prepared via adjusting the Co/Mn molar ratio using mixed carbonates as the precursors. The as-prepared CoxMn3-xO4 catalysts exhibit excellent catalytic activities for toluene oxidation due to the synergistic effect of abundant oxygen vacancies and the optimal molar ratio of Co3+/Mn2+–Co2+/Mn3+ coupled redox ion pairs. The porous hollow hierarchical structure of CoxMn3-xO4 is conducive to maintain good long-term structural stability and activity stabilities. The catalytic activity of CoxMn3-xO4 shows no significant loss during the 100 h of on-stream stability test and the 5 vol% water vapor inhibition test, showing excellent anti-sintering ability, high-efficiency mass transfer ability and anti-moisture ability.

Formation of Catalytically Active Nanoparticles under Thermolysis of Silver Chloroplatinate(II) and Chloroplatinate(IV)

Filatov, Evgeny,Smirnov, Pavel,Potemkin, Dmitry,Pishchur, Denis,Kryuchkova, Natalya,Plyusnin, Pavel,Korenev, Sergey

, (2022/02/19)

The thermal behaviour of Ag2 [PtCl4 ] and Ag2 [PtCl6 ] complex salts in inert and reducing atmospheres has been studied. The thermolysis of compounds in a helium atmosphere is shown to occur in two stages. At the first stage, the complexes decompose in the temperature range of 350–500?C with the formation of platinum and silver chloride and the release of chlorine gas. At the second stage, silver chloride is sublimated in the temperature range of 700–900?C, while metallic platinum remains in the solid phase. In contrast to the thermolysis of Ag2 [PtCl6 ], the thermal decomposition of Ag2 [PtCl4 ] at 350?C is accompanied by significant heat release, which is associated with disproportionation of the initial salt to Ag2 [PtCl6 ], silver chloride, and platinum metal. It is confirmed by DSC measurements, DFT calculations of a suggested reaction, and XRD. The thermolysis of Ag2 [PtCl4 ] and Ag2 [PtCl6 ] compounds is shown to occur in a hydrogen atmosphere in two poorly separable steps. The compounds are decomposed within 170–350?C, and silver and platinum are reduced to a metallic state, while a metastable single-phase solid solution of Ag0.67Pt0.33 is formed. The catalytic activity of the resulting nanoalloy Ag0.67Pt0.33 is studied in the reaction of CO total (TOX) and preferential (PROX) oxidation. Ag0.67Pt0.33 enhanced Pt nano-powder activity in CO TOX, but was not selective in CO PROX.

Investigating the effects of various synthesis routes on morphological, optical, photoelectrochemical and photocatalytic properties of single-phase perovskite BiFeO3

Chang Chien, Shui-Wen,Jaffari, Zeeshan Haider,Kumar, Dileep,Lam, Sze-Mun,Ng, Ding-Quan

, (2021/08/23)

Herein, various BiFeO3 morphologies, including sheet-like, coral-like and rod-like structures, were synthesized via co-precipitation (CP), hydrothermal (HT), and sol-gel (SG) synthesis routes, respectively. The as-synthesized samples were characterized by physicochemical techniques to investigate their crystal structure, optical and photoelectrochemical properties. The SG-BiFeO3 sample exhibited remarkable direct sunlight photocatalytic degradation of phenol (98.95%), superior to those of the HT-BiFeO3 (77.4%) and CP-BiFeO3 (66.9%) in 120 min. The SG-BiFeO3 sample was the most effective among all due to the lower energy band gap value and highest separation of photogenerated charge carriers, which was validated by the UV–vis absorption, photoluminescence (PL) and photoelectrochemical measurements. The recycling and ferric (Fe3+) ion leakage test suggested that the SG-BiFeO3 sample was highly stable for up to six consecutive runs. The radical scavenger studies implied that the photogenerated hole (h+), hydrogen peroxide (H2O2) and hydroxyl radicles (?OH) were the dominant reactive species. Finally, based on these, a possible photocatalytic mechanism for phenol degradation over SG-BiFeO3 sample was also postulated.

Syntheses of two copper metal-organic frameworks with tri(1,2,4-triazole) and biscarboxylate and graphene oxide composites for decomposition of dye by visible-light driven and ultrasonic assisted

Hu, Chuan-Jiang,Li, Bao-Long,Li, Hai-Yan,Li, Le-Yan,Ma, Li-Xiao,Zha, Miao,Zhou, Wen-Jing

, (2022/01/06)

Two crystalline and nano-sized new Cu(II) MOFs {[Cu(ttpa)(1,3-bdc)(H2O)]·CH3OH}n (Cu(ttpa)-1) and {[Cu(ttpa)(mip)(H2O)]?2H2O} (Cu(ttpa)-2) were prepared and characterized (ttpa ?= ?tris(4-(1,2,4-triaz

Hydrothermally grown α-MoO3 microfibers for photocatalytic degradation of methylene blue dye

Dewangan, Khemchand,Singh, Dadan,Satpute, Nilesh,Singh, Ritika,Jaiswal, Adhish,Shrivas, Kamlesh,Bahadur, Indra

, (2021/12/13)

Adsorption and photodegradation efficiency of α-MoO3 microfibers towards methylene blue (MB) dye in the aqueous solution were reported. To obtain high-quality α-MoO3 microfibers, an aqueous solution of (NH4)6Mo7O24·4H2O and citric acid was hydrothermally treated (180 °C, 12 h) in the presence of HNO3. The possible growth mechanism of microfibers in the hydrothermal reaction is explained. XRD and TEM studies provide shreds of evidence that microfibers have crystallized in a pure orthorhombic phase and grown up in the direction of [0 0 1]. The structural bonding between molybdenum and oxygen constituent elements of microfibers was further confirmed by XPS, FTIR, and Raman techniques. The estimated optical band gap of α-MoO3 microfibers (Eg = 2.68 eV) lies in the visible region, making them suitable for visible light photocatalytic application. MB adsorption and degradation capacity of microfibers were performed in the dark and light, respectively. The photocatalytic properties revealed that 90 % MB dye was degraded within 120 min illumination. Moreover, the good photocatalytic recycling capability of α-MoO3 microfibers makes them a promising photocatalyst to eliminate organic pollutants from water.

Process route upstream and downstream products

Process route

3,4-dibromo-2,6-dimethyl-heptan-2-ol
859187-55-6

3,4-dibromo-2,6-dimethyl-heptan-2-ol

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
zersetzt sich auch im Dunkeln rasch unter Abspaltung;
2,3-dibromo-2-methyl-succinic acid
37951-41-0

2,3-dibromo-2-methyl-succinic acid

3-bromo-4-methyl-2,5-furandione
59107-74-3

3-bromo-4-methyl-2,5-furandione

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
low-melting 2,3-dibromo-2-methyl-succinic acid; bei der Destillation;
1-bromo-ethenesulfonic acid
97925-62-7

1-bromo-ethenesulfonic acid

carbon dioxide
124-38-9,18923-20-1

carbon dioxide

sulfuric acid
7664-93-9

sulfuric acid

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
1-bromo-ethenesulfonic acid
97925-62-7

1-bromo-ethenesulfonic acid

carbon dioxide
124-38-9,18923-20-1

carbon dioxide

sulfuric acid
7664-93-9

sulfuric acid

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
1-bromo-ethenesulfonic acid
97925-62-7

1-bromo-ethenesulfonic acid

carbon dioxide
124-38-9,18923-20-1

carbon dioxide

sulfuric acid
7664-93-9

sulfuric acid

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
4-methyl-pent-3-en-2-one
141-79-7

4-methyl-pent-3-en-2-one

methylmagnesium iodide

methylmagnesium iodide

2,4-Dimethyl-1,3-pentadiene
1000-86-8

2,4-Dimethyl-1,3-pentadiene

water
7732-18-5

water

Conditions
Conditions Yield
bei der Destillation;
bis-(4-hydroxy-3,5-dimethyl-phenyl)-methylium; [bis-(4-hydroxy-3,5-dimethyl-phenyl)-methyl]-bromide

bis-(4-hydroxy-3,5-dimethyl-phenyl)-methylium; [bis-(4-hydroxy-3,5-dimethyl-phenyl)-methyl]-bromide

water
7732-18-5

water

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
at 180 ℃;
carbon dioxide
124-38-9,18923-20-1

carbon dioxide

carbon monoxide
201230-82-2

carbon monoxide

water
7732-18-5

water

hydrogen
1333-74-0

hydrogen

Conditions
Conditions Yield
With oxygen; at 850 ℃; for 24h; under 760.051 Torr; Temperature; Catalytic behavior; Flow reactor;
55%
With oxygen; palladium; at 300 - 1200 ℃; under 1350.14 - 15001.5 Torr; Gas phase;
With oxygen;
With oxygen;
Ni-Fe/La2O3 catalyst, CH4:O2=2:1, 1 atm, 600-900 °C, 85 % CO selectivity;
With oxygen; at 650 ℃; Reagent/catalyst; Temperature; Catalytic behavior;
With Ni#NiO; oxygen; at 720 ℃; under 750.075 Torr; Reagent/catalyst; Flow reactor;
Conditions
Conditions Yield
Product distribution / selectivity;
Conditions
Conditions Yield
Product distribution / selectivity;

Global suppliers and manufacturers

Global( 195) Suppliers
  • Company Name
  • Business Type
  • Contact Tel
  • Emails
  • Main Products
  • Country
  • Shanghai Upbio Tech Co.,Ltd
  • Business Type:Lab/Research institutions
  • Contact Tel:+86-21-52196435
  • Emails:upbiocn@hotmail.com
  • Main Products:88
  • Country:China (Mainland)
  • Chemwill Asia Co., Ltd.
  • Business Type:Manufacturers
  • Contact Tel:021-51086038
  • Emails:sales@chemwill.com
  • Main Products:56
  • Country:China (Mainland)
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