99.98% trace metals basis12013-10-4Relevant articles and documents
Solid state synthesis of binary metal chalcogenides
Shaw, Graham A.,Morrison, Daniel E.,Parkin, Ivan P.
, p. 1872 - 1875 (2001)
Solid state reaction of metal halides MXn (n = 1 or 2) with stoichiometric amounts of sodium chalcogenide (Na2S2 or Na2E where E = S, Se or Te) at 300 °C for 48 h in evacuated ampoules affords a range of transition and main-group metal chalcogenides: ME2 (M = Fe or Co, E = S or Te); M(1-x)E (M = Fe or Co, E = S); Ag2E (E = S, Se or Te), Ni(1-xE (E = S, Se or Te); NiS2, MnS, FeSe, SnSe and SnTe along with co-formed salt. Washing of the highly sintered, fused product mixture with water resulted in isolation of crystalline binary chalcogenides, typically of a single phase in good yield (90%). The products were characterised by X-ray powder diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and infrared spectroscopy.
On the synergism between La2O2S and CoS2 in the reduction of SO2 to elemental sulfur by CO
Ma, Jianxin,Fang, Ming,Lau, Ngai Ting
, p. 251 - 259 (1996)
In our study of the catalytic reduction of SO2 to elemental sulfur by CO in the presence of La2O2S and CoS2, a synergistic effect between the two sulfides was observed which not only increased the catalytic activity but also suppressed the formation of the side-product COS. It was also found that the crystal phase of CoS2, which can be easily reduced by CO, could be retained when La2O2S coexisted even in small quantities. A mechanism was proposed based on the COS intermediate mechanism and the remote control concept.
Synthesis and properties of cobalt sulfide phases: CoS2 and Co9S8
Kumar, Nitesh,Raman, Natarajan,Sundaresan, Athinarayanan
, p. 1069 - 1074 (2014)
Single phase cobalt disulfide (CoS2) nanoparticles were prepared by thermal decomposition of cobalt-thiourea complex at a low temperature (400 °C). CoS2 nanoparticles exhibit ferromagnetic ordering at 122 K below which the temperatur
X-RAY PHOTOELECTRON SPECTRA OF 3d TRANSITION METAL PYRITES.
van der Heide,Hemmel,van Bruggen,Hass
, p. 17 - 25 (1980)
Photoelectron spectra of the synthetic compounds FeS//2, CoS//2, NiS//2, MnSe//2, CoSe//2, and NiSe//2 and of a natural crystal of MnS//2, all with the pyrite structure, are reported. The sulfur 3s and selenium 4s contributions are split into peaks for bonding and antibonding orbitals due to the covalent bonding in the molecular anion pairs. The difference in lineshape of the peaks for the bonding and antibonding orbitals is attributed to vibronic effects. The metal 2p//3/////2 spectra show the effects of multiplet splitting and satellites due to shake-up or shake-off processes. The valence band spectra consist of slightly overlapping contributions of anion p and metal 3d electrons. The metal 3d spectrum of FeS//2 has a single strong peak of width 0. 9 eV.
Pyrite formation via kinetic intermediates through low-temperature solid-state metathesis
Martinolich, Andrew J.,Neilson, James R.
, p. 15654 - 15659 (2014)
The preparation of materials with limited phase stabilities yet high kinetic activation barriers is challenging. Knowledge of their possible formation pathways aids in addressing these challenges. Metathesis reactions present an approach to circumvent these barriers; however, solid-state metathesis reactions are often too rapid from extensive self-heating to understand the reaction. The stoichiometric reaction of MCl2 salts (M = Mn, Fe, Co, Ni, Cu, Zn) with Na2S2 enables the formation of pyrite (FeS2), CoS2, and NiS2 at low temperatures (250-350 °C). Na2S2 has the same polyanionic dimer as found in the pyrite structure, which would suggest the possibility of a facile ion-exchange reaction. However, from high-resolution synchrotron X-ray diffraction and differential scanning calorimetry, the energetic driving force does not appear to result solely from NaCl formation but also from formation of intermediate and pyrite phases. It is apparent that the reaction proceeds through polyanionic disproportionation and formation of a low-density alkali-rich intermediate, followed by anionic comproportionation and atomic rearrangement into the pyrite phase. These results have profound implications for the use of low-temperature metathesis in achieving materials by design.
Electronic effect of substituents on the hydrodesulfurization of ring substituted benzenethiols
Konuma,Takase,Kameda,Itabashi
, p. 229 - 242 (1993)
To clarify the electronic factors of the reactants affecting hydrodesulfurization (HDS) reactivity, the o-, m- and p-isomers of aminobenzenethiol (ABT), methoxybenzenethiol (MBT) and toluenethiol (TT) were hydrogenolyzed by a batch method over CoS2, NiS2 and a presulfided commercial HDS catalyst. In the hydrogenolysis of all the isomers of ABT, MBT and TT, HDS by cleavage of the C-S bond occurred selectively and was promoted by the presence of electron-releasing substituents in the ortho- and para-positions. Among the quantities obtained from the MINDO/3 calculation for a reactant, the next three are especially interesting: these are the coefficients of the ipso-carbon and the sulfur atoms in the highest occupied π-orbital (π-HOMO), CCHOMO and CSHOMO, and the energy level of π-HOMO. The differences in reactivity among the isomers of a substituted benzenethiol can be interpreted by use of the frontier π-electron densities (FED), 2(CCHOMO)2 and 2(CSHOMO)2. On the other hand, the differences in reactivity among the molecules, i.e., ABT, MBT, TT, and benzenethiol, shows a close correlation with the ratio of the two FEDs, (CCHOMO/CSHOMO)2, and also with the energy level of π-HOMO. It is suggested that the energy level and the FED assume an important role in the HDS reactivities and that the magnitudes of the FEDs on the positions of both the sulfur and the ipso carbon atoms affect the reactivities not independently but concertedly.
Copper dopants improved the hydrogen evolution activity of earth-abundant cobalt pyrite catalysts by activating the electrocatalytically inert sulfur sites
Zhang, Jingyan,Xiao, Baorui,Liu, Xiaoli,Liu, Peitao,Xi, Pinxian,Xiao, Wen,Ding, Jun,Gao, Daqiang,Xue, Desheng
, p. 17601 - 17608 (2017)
Cobalt pyrite (CoS2) is considered to be a promising catalyst for the hydrogen evolution reaction (HER) due to its intrinsic metallicity and high catalytic activity. However, the catalytically inert S-sites and sluggish reaction kinetics severely impede its commercial application. Herein, combining systematic theoretical and experimental approaches, a highly active and stable Cu doped CoS2 catalyst for the HER is demonstrated. Cu dopants are proven to not only reduce the hydrogen adsorption free energy (ΔGH?) of the Co sites from 0.41 eV to -0.13 eV, but also arouse the inert S sites with the low ΔGH? of -0.11 eV. A large cathode current density (10 mA cm-2 at 52 mV), low Tafel slope (42 mV dec-1), large exchange current density (0.68 mA cm-2), and good stability were observed in the Co0.93Cu0.07S2 catalyst, which are better than those found for the previously reported CoS2-based catalysts. The success of improving the electrochemical performance via the introduction of Cu dopants offers new opportunities in the development of high performance CoS2-based electrodes for other energy-related applications.
Preparation of CoS2 nanoflake arrays through ion exchange reaction of Co(OH)2 and their application as counter electrodes for dye-sensitized solar cells
Tsai, Jung-Che,Hon, Min-Hsiung,Leu, Ing-Chi
, p. 4328 - 4333 (2015)
The cobalt sulfide nanoflake arrays prepared by the transformation of Co(OH)2 nanoflake arrays using the ion exchange reaction method were incorporated into Pt-free dye-sensitized solar cells (DSSCs). Morphologies and crystal structures of the cobalt sulfide and cobalt hydroxide nanoflakes arrays were characterized by SEM, TEM and XRD analyses. The electrochemical properties were determined by cyclic voltammetry (CV) measurement. The cobalt sulfide nanoflakes which were composed of CoS2 single crystals and their aggregates dispersing in the amorphous cobalt sulfide matrix were completely transferred by substitution of S2- for O2- in the ion exchange reaction. The DSSC assembled with cobalt sulfide nanoflake arrays as the counter electrode showed a photovoltaic conversion efficiency of 5.20%, which was close to that of DSSC with sputtered Pt as the counter electrode (5.34%). Therefore, the cobalt sulfide nanoflake array film can be considered as a promising alternative counter electrode for use in DSSCs due to its large surface area and high electrocatalytic performance.
New low-temperature preparations of some simple and mixed Co and Ni dispersed sulfides and their chemical behavior in reducing atmosphere
Bezverkhyy,Danot,Afanasiev
, p. 1764 - 1768 (2003)
A series of simple (CoS2, Co9S8, NiS2, NiS, Ni3S2) and mixed sulfides (NiCo2S4, Ni0.33Co0.67S2, Ni3Co6S8, CuCo2S4, Cu0.33Co0.67S2) was prepared using low-temperature procedures. To obtain the mixed sulfides, the mixtures of the solutions of the corresponding salts were precipitated by Na2S and then heated in a sulfiding atmosphere at 300 °C. It has been found that the product phase composition depends on the sulfiding atmosphere. Using a H2S/Ar mixture leads to pyrite type sulfides, whereas treatment in H2S/H2 flow allowed the preparation of Ni-Co and Cu-Co thiospinels. The as prepared highly dispersed single-phase materials were characterized by X-ray powder diffraction, scanning electron microscopy, temperature-programmed reduction (TPR), elemental analysis, and BET surface area measurements.
One-step synthesis of nickel cobalt sulphides particles: Tuning the composition for high performance supercapacitors
Zhang, Huaihao,Guan, Bing,Gu, Jiangna,Li, Yu,Ma, Chi,Zhao, Jing,Wang, Tianyi,Cheng, Changjing
, p. 58916 - 58924 (2016)
NiS2-CoS2 composites with different Ni and Co molar ratios for supercapacitors (SCs) were synthesized by one-step hydrothermal co-deposition method using cheap Na2S2O3·5H2O as sulfur source. With the increase of Ni content, the composites particle size increases gradually and the hollow sphere structure becomes more obvious. The electrochemical measurements demonstrate that these composites possess a high specific capacitance (Cm) performance, good rate capability and long cycle stability. To be specific, the Cm of Ni/Co/S-1 composite is the largest, up to 954.3 F g-1 at 1 A g-1, and as high as 309.5 F g-1 even at large current density of 20 A g-1. Furthermore, the Ni/Co/S-1 maintains 99.9% of its initial Cm after 1000 cycles at 5 A g-1. Moreover, the asymmetric supercapacitors with Ni/Co/S-1 as positive electrode and active carbon as negative electrode are of prominent energy density of 29.3 W h-1 kg-1 at the power density of 0.7 kW kg-1, and superior cycling stability of 99.1% initial value retention after 1000 cycles.
Facet-controlled morphology of cobalt disulfide towards enhanced oxygen reduction reaction
Singh, Vikram,Tiwari, Aarti,Nagaiah, Tharamani C.
, p. 22545 - 22554 (2018)
Catalytic activity has a significant contribution from exposed facets which are prominently correlated with morphology. It has been witnessed that even a small refinement in morphology alters the catalytic activity over several folds which is a key towards catalyst design. The present study thereby explores the design of octahedral CoS2 crystals with the aim of exposing highly active facets for the oxygen reduction reaction (ORR) which were carefully synthesized to incorporate carbon inherently. One-pot hydrothermal synthesis was employed using trisodium citrate and sodium thiosulfate. The resultant crystals of octahedral CoS2 with exposed {111} and {220} planes were revealed by HR-TEM and XRD studies. Detailed structure-activity insight regarding ORR was obtained using rotating ring disk electrode and electrochemical quartz crystal microbalance (EQCM) analysis and facet controlled octahedral CoS2 was shown to have the 50 fold increase in activity relative to other variants in an acidic medium and is comparable to a state-of-the-art Pt/C (20%) catalyst. The local catalytic activity of the CoS2 catalyst was visualized by the redox-competition mode of scanning electrochemical microscopy (RC-SECM).
Hierarchical CoS2/Ni3S2/CoNiO:X nanorods with favorable stability at 1 A cm-2 for electrocatalytic water oxidation
Lee, Husileng,Wu, Xiujuan,Ye, Qilun,Wu, Xingqiang,Wang, Xiaoxiao,Zhao, Yimeng,Sun, Licheng
, p. 1564 - 1567 (2019)
Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (η) as low as 256 mV to exhibit a current density of 10 mA cm-2 in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm-2 for one week in 30% KOH solution with only 25 mV increment of η. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications.
High-performance dye-sensitized solar cell based on an electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/cobalt sulfide nanocomposite membrane electrolyte
Vijayakumar,Subramania,Fei, Zhaofu,Dyson, Paul J.
, p. 52026 - 52032 (2015)
Electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanocomposite membranes incorporated with different weight percentages (1, 2 and 3 wt%) of cobalt sulfide (CoS) were prepared by an electrospinning technique. The surface morphology, crystallinity, porosity and electrolyte uptake of the electrospun nanocomposite membranes were examined. The prepared electrospun PVdF-HFP/CoS nanocomposite membranes (esCPM) were activated by an ionic liquid electrolyte containing 0.5 M LiI, 0.05 M I2, 0.5 M 4-tert-butylpyridine and 0.5 M 1-butyl-3-methylimidazolium iodide in acetonitrile to obtain electrospun PVdF-HFP/CoS nanocomposite membrane electrolytes (esCPMEs). The uniformly dispersed CoS nanoparticles increased charge transport and facilitated the diffusion of the redox couple in the electrolyte system. The electrochemical characteristics of the dye-sensitized solar cells depended on the amount of CoS incorporated into the esCPMEs. The photovoltaic performance of the dye-sensitized solar cell assembled using the esCPME incorporated with 1 wt% of CoS was measured and found to be 7.34%, which is higher than that of the dye-sensitized solar cell assembled using the esPME without CoS (6.42%).
Cobalt-Doped FeS2Nanospheres with Complete Solid Solubility as a High-Performance Anode Material for Sodium-Ion Batteries
Zhang, Kai,Park, Mihui,Zhou, Limin,Lee, Gi-Hyeok,Shin, Jeongyim,Hu, Zhe,Chou, Shu-Lei,Chen, Jun,Kang, Yong-Mook
, p. 12822 - 12826 (2016)
Considering that the high capacity, long-term cycle life, and high-rate capability of anode materials for sodium-ion batteries (SIBs) is a bottleneck currently, a series of Co-doped FeS2solid solutions with different Co contents were prepared by a facile solvothermal method, and for the first time their Na-storage properties were investigated. The optimized Co0.5Fe0.5S2(Fe0.5) has discharge capacities of 0.220 Ah g?1after 5000 cycles at 2 A g?1and 0.172 Ah g?1even at 20 A g?1with compatible ether-based electrolyte in a voltage window of 0.8–2.9 V. The Fe0.5 sample transforms to layered NaxCo0.5Fe0.5S2by initial activation, and the layered structure is maintained during following cycles. The redox reactions of NaxCo0.5Fe0.5S2are dominated by pseudocapacitive behavior, leading to fast Na+insertion/extraction and durable cycle life. A Na3V2(PO4)3/Fe0.5 full cell was assembled, delivering an initial capacity of 0.340 Ah g?1.
One-step hydrothermal synthesis of a CoS2@MoS2 nanocomposite for high-performance supercapacitors
Huang, Feng,Meng, Rongde,Sui, Yanwei,Wei, Fuxiang,Qi, Jiqiu,Meng, Qingkun,He, Yezeng
, p. 844 - 851 (2018)
A MoS2-coated CoS2 composite has been prepared successfully via a one-step hydrothermal method. This CoS2@MoS2 hybrid material has a distinct morphology with few-layer MoS2 wrapping the CoS2 nanoparticles. Serving as a supercapacitor electrode, the obtained CoS2@MoS2 hybrid material exhibits a remarkable specific capacitance of 1038 F/g, a high rate capability of 71.7%, and excellent cycling stability of 84.76% retention after 10000 cycles. The superior electrochemical properties of the CoS2@MoS2 nanocomposite are attributed to the synergistic effects between the layered MoS2 and conductive CoS2.
Synthesis of Lattice-Contracted Cobalt Disulfide as an Outstanding Oxygen Reduction Reaction Catalyst via Self-assembly Arrangement
Zhang, Hao,Wang, Zhiqiang,Ma, Chenglong,Zhou, Zhenhua,Cao, Limei,Gong, Xueqing,Dong, Chunxiao,Yang, Ji
, p. 1388 - 1395 (2021)
Identifying high-performance non-precious metal-based catalysts at the cathode is a major challenge for future practical applications. Herein, a soft-template route through a self-assembly arrangement of sulfur sources was successfully developed, facilitating the anion exchange. In addition, compared with pristine cobalt disulfide synthesized without templates, the cobalt disulfide prepared using the new method presented a lattice shrinking phenomenon due to the hindrance of cobalt hydroxide crystal cell. Based on X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculation, increased occupancy of eg orbitals was verified for the cobalt disulfide after shrinkage, which was the main factor for enhancing the intrinsic activity of the catalyst. Besides the microscopic morphologic structure, elementary composition, and the valence state of the elements, the possible growth process of the cobalt disulfide was also discussed in detail. As catalyst for the oxygen reduction reaction, CoS2 showed a similar half-wave potential (0.81 vs. 0.84 V for Pt/C) and higher diffusion-limiting current density (reaching 5.33 vs. 5.19 mA cm?2 for Pt/C) than a commercial Pt/C catalyst. Hence, our results provide a rational design direction for this type of catalysts.
Magnetocaloric effect of Co(S1-xSex) 2
Wada,Tanaka,Tajiri
, p. 706 - 708 (2005)
The magnetic entropy change, ΔSM, was measured for Co(S1-xSex)2 with 0≤x≤0.103, which is a system showing the itinerant electron metamagnetism (IEM). It was found that the peak value of -ΔSM shows a maximum at around x=0.08. The origin of this behavior is discussed in terms of the Clausius-Clapeyron relation.
Low-temperature molten salt synthesis of MoS2@CoS2 heterostructures for efficient hydrogen evolution reaction
He, Song,Du, Hongfang,Wang, Ke,Liu, Qianchi,Sun, Jinmeng,Liu, Yuhang,Du, Zhuzhu,Xie, Linghai,Ai, Wei,Huang, Wei
, p. 5548 - 5551 (2020)
A versatile low-temperature molten salt approach has been developed for fabricating a MoS2@CoS2 heterostructure electrocatalyst, where low-cost molten KSCN serves as both the reaction medium and sulfur source. The as-obtained electrocatalyst with a defect-rich structure is highly efficient for the hydrogen evolution reaction (HER), delivering a low overpotential of 96 mV at an HER current density of 10 mA cm-2, a small Tafel slope of 60 mV dec-1, and outstanding durability. Density functional theory (DFT) calculations suggest that the heterostructures present an optimized Gibbs free energy of hydrogen adsorption (ΔGH?) close to zero, which is responsible for the excellent HER performance.
Single-step microwave mediated synthesis of the CoS2 anode material for high rate hybrid supercapacitors
Amaresh,Karthikeyan,Jang,Lee
, p. 11099 - 11106 (2014)
A short time microwave irradiation based synthesis method of phase pure cubic CoS2 nanoparticles is reported in this study for the first time. The energy density (ED) of hybrid supercapacitors based on CoS2 as an anode having activated carbon as a cathode has been enhanced by using the higher operating potential of organic electrolytes and by increasing the concentration of the mobile ionic species at the negative electrode, in addition to the lithium ions present in the electrolyte. The specific capacitance delivered by non-lithiated CoS2 nanoflakes was 52 F g-1 at a current rate of 0.7 A g-1 between 0 and 3 V using a LiPF 6-based electrolyte. Increasing the concentration of the mobile ionic species, i.e., lithium, at the anode enhanced the performance of the hybrid supercapacitor to 119 F g-1 at a current rate of 0.7 A g -1. The hierarchical arrangement of pores in the electroactive material allowed high electrolyte access and reduced the length of the ionic pathway. Consequently, the lithiated form exhibited an ED of 37 W h kg -1 with a power density of 1 kW kg-1 at a current rate of 0.7 A g-1, compared to only 15 W h kg-1 for the non-lithiated sample. Furthermore, both samples maintained superior stability over extended cycling for 10 000 cycles at a very high PD of 4 kW kg -1 with a capacitance retention of 100% for the lithiated sample and 80% for the non-lithiated sample. These results will be useful in the fabrication of high ED, high rate hybrid supercapacitors for electric vehicle applications.
Magnetic properties of the itinerant metamagnetic system Co(S1-xSex)2 under high magnetic fields and high pressure
Goto,Shindo,Takahashi,Ogawa
, p. 14019 - 14028 (1997)
The magnetization of the Co(S1-x-Sex)2 system with 0≤x≤0.2 has been measured under high magnetic fields and high pressure. Ferromagnetic CoS2 exhibits a second-order transition at T2=122 K. Substitution of 10% Se for S in CoS2 reduces the Curie temperature to Tc.=27 K and the transition to first order. Co(S1-xSex)2 with 0.12≤x becomes an exchange-enhanced Pauli paramagnet. The itinerant metamagnetic transition has been observed in the paramagnet. Co(S0.9Se0.1)2 also shows a transition just above Tc. Using the experimental data, the magnetic phase diagram of Co(S1-xSex)2 is determined. With increasing pressure, the Curie temperature of CoS2 decreases and the ferromagnetic transition changes to first order at P≈0.4 GPa. In the pressure regime of the first-order transition P>0.4 GPa, the metamagnetic transition is observed just above Tc. In Co(S0.9Se0.1)2, the ferromagnetism disappears at 0.25 GPa and paramagnetism appears. The observed magnetic properties and the magnetic phase diagram of Co(S1-x.Sex)2 can be qualitatively described with a theory of the itinerant electron metamagnetism at finite temperatures.
Hierarchical mesoporous CoS2 microspheres: Morphology-controlled synthesis and their superior pseudocapacitive properties
Xing, Jia-Chao,Zhu, Yan-Li,Li, Meng-Yao,Jiao, Qing-Jie
, p. 285 - 292 (2014)
A simple and novel strategy has been developed for the morphology-controlled synthesis of hierarchical CoS2 microspheres. The hierarchical mesoporous CoS2 architecture constructed by ultrathin nanosheets, when applied as electrode materials for supercapacitors, achieves a highest specific capacitance of 718.7 F g-1 at 1 A g-1 under a high mass loading, excellent rate capability (66.3% capacitance retention from 1 A g-1 to 20 A g-1), and good cycling stability (only a loss of 7.0% in the specific capacitance after 1000 cycles). Therefore, this work provides a promising approach for the rational design and synthesis of morphology-tunable micro/nanomaterials with superior properties for supercapacitors and other electrochemical applications.
Self-template synthesis of hierarchical CoMoS3 nanotubes constructed of ultrathin nanosheets for robust water electrolysis
Zhang, Xiao,Guo, Jinxue,Zhang, Xinqun,Sun, Yanfang,Tang, Lin
, p. 11309 - 11315 (2017)
Exploration of pH-universal and durable catalysts with specific structure and high performance is desirable but challenging for electrochemical water splitting. Aiming at this goal, hierarchical CoMoS3 nanotubes constructed of ultrathin nanosheet subunits are prepared via a self-sacrifice template method. The conversion from CoMoO4 nanorods to hierarchical MoCoS3 nanotubes is successfully realized through a facile solvothermal process. The obtained sample simultaneously possesses advanced structural superiority and synergism of ternary Co-Mo-S. Endowed with these advantages, MoCoS3 can serve as a pH-universal and high-performance electrocatalyst for hydrogen evolution, delivering low onset overpotential, small overpotential required to generate current density of 10 mA cm-2, and good stability. Moreover, it exhibits excellent catalytic performance in the electrochemical oxygen evolution reaction, making it a promising dual-functional catalyst for water electrolysis.
Synthesis of CuS@CoS2 Double-Shelled Nanoboxes with Enhanced Sodium Storage Properties
Fang, Yongjin,Guan, Bu Yuan,Luan, Deyan,Lou, Xiong Wen (David)
, p. 7739 - 7743 (2019)
Metal sulfides have received considerable attention for efficient sodium storage owing to their high capacity and decent redox reversibility. However, the poor rate capability and fast capacity decay greatly hinder their practical application in sodium-ion batteries. Herein, an elegant multi-step templating strategy has been developed to rationally synthesize hierarchical double-shelled nanoboxes with the CoS2 nanosheet-constructed outer shell supported on the CuS inner shell. Their structure and composition enable these hierarchical CuS@CoS2 nanoboxes to show boosted electrochemical properties with high capacity, outstanding rate capability, and long cycle life.
High performance electrocatalysis for hydrogen evolution reaction using nickel-doped CoS2 nanostructures: experimental and DFT insights
Cui, Yan,Zhou, Chunwu,Li, Xinze,Gao, Yuan,Zhang, Jian
, p. 428 - 435 (2017)
Development of non-noble-metal electrocatalysts with high activity and durability is a competitive strategy for the practical applications of water splitting which including hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER). In this work, high-quality CoS2 ultrathin nanosheets were synthesized through a simple and efficient hydrothermal method. After merging 10% wt Ni, the bimetal catalyst (Co0.9Ni0.1S2) displays excellent catalytic activity (10 mA cm?2 at an overpotential of 156 mV and a small Tafel slope of 52 mV dec?1) as well as stability (over 3000 cycles without obvious decay) in acid condition. Based on the results of Density Functional Theory (DFT) calculations, H+ adsorbed competition, hydrogen formation energetic and kinetics are proposed to help us understand the high efficient HER process over the Co0.9Ni0.1S2 (CNS) ultrathin nanosheets.
Magnetocaloric effect of Co(S1-xSex)2 under high pressure
Sadakuni, Osamu,Mituda, Akihiro,Wada, Hirofumi
, (2010)
We examined the magnetocaloric effect of Co(S1-xSe x)2, which shows typical itinerant electron metamagnetism, under high pressures up to 1.2 GPa. It was found that the magnetic entropy change, δSM, of x = 0 incr
One-pot synthesis of MoS2/CoS2 yolk-shell nanospheres
Jia, Yulong,Lin, Yinhe,Ma, Ying,Yin, Guoliang
, (2021/12/31)
In this work, MoS2/CoS2 yolk-shell nanospheres are synthesized by a one-pot hydrothermal reaction. Furthermore, the yolk-shell spherical morphologies are characterized and confirmed by SEM, TEM characterizations; and the components of CoS2 and MoS2 are investigated by XRD and XPS analysis. It is revealed that the Co precursor and thiourea result in the formation of hollow CoS2 nanospheres, while the Co precursor, Mo precursor and thiourea lead to the fabrication of MoS2/CoS2 yolk-shell nanostructure. The possible growth mechanism of MoS2/CoS2 yolk-shell nanospheres is suggested based on the comparative experiments and characterization of intermediate samples. This research provides a feasible and new strategy to prepare the MoS2/CoS2 hybrid material with yolk-shell architecture.
MoS2/CoS2 heterostructures embedded in N-doped carbon nanosheets towards enhanced hydrogen evolution reaction
Ji, Kang,Matras-Postolek, Katarzyna,Shi, Ruixia,Chen, Ling,Che, Quande,Wang, Junpeng,Yue, Yunlong,Yang, Ping
, (2021/09/28)
MoS2/CoS2 heterostructures on nitrogen-doped carbon nanosheets as an efficient electrocatalyst for hydrogen evolution reaction (HER) are prepared using zeolitic imidazolate frameworks-67 as precursors. Two dimensional (2D)/2D MoSsub
