12134-02-0Relevant articles and documents
Facile synthesis of CoX (X = S, P) as an efficient electrocatalyst for hydrogen evolution reaction
Li, Jiayuan,Zhou, Xuemei,Xia, Zhaoming,Zhang, Zhiyun,Li, Jing,Ma, Yuanyuan,Qu, Yongquan
, p. 13066 - 13071 (2015)
Developing environmentally-friendly and earth-abundant electrocatalysts is desirable for an efficient hydrogen evolution reaction (HER). Herein, we report a facile and controllable synthesis of CoX (X = S, P) nanocatalysts by the chemical conversion of thin Co(OH)2 nanoplates under mild conditions. Both catalysts delivered high catalytic activity for HER. Small onset potentials of 59 and 32 mV, along with low Tafel slopes of 56.2 and 54.8 mV dec-1, were observed for CoS and CoP, respectively. Analyses suggest that the better HER performance of CoP nanocatalysts could be attributed to the intrinsically more positively charged nature of the Co metal center, the longer Co-P bond length, and more catalytic active sites due to the smaller size of the CoP nanocatalysts. High catalytic stability in acidic media was also observed for both CoS and CoP catalysts for a duration of 18 hours.
Preparation of Yolk–Shell-Structured CoxFe1?xP with Enhanced OER Performance
Yue, Song,Wang, Shanshan,Jiao, Qingze,Feng, Xueting,Zhan, Kun,Dai, Yiqing,Feng, Caihong,Li, Hansheng,Feng, Tongying,Zhao, Yun
, p. 4461 - 4470 (2019)
The design and development of low-cost, highly efficient, and stable electrocatalysts to take the place of noble-metal catalysts for the oxygen evolution reaction (OER) remain a significant challenge. Herein, the synthesis of yolk–shell-structured binary transition metal phosphide CoxFe1?xP with different Co/Fe ratios by phosphidation of a cobalt ferrite precursor is reported. The as-synthesized CoxFe1?xP catalysts were used for the OER. All yolk–shell CoxFe1?xP catalysts with different Co/Fe ratios showed much better performance than the corresponding solid catalyst. The formation of Co oxides on the catalyst surface during OER and the optimal Co/Fe ratio were found to be critical to their activity. Among the as-prepared CoxFe1?xP catalysts, that with a Co/Fe ratio of 0.47/0.53 (Co0.47Fe0.53P) exhibited the best performance. Co0.47Fe0.53P has an overpotential of 277 mV at a current density of 10 mA cm?2, a Tafel slope of 37 mV dec?1, and superior stability in alkaline medium. The outstanding performance is partly ascribed to the transfer of valence electrons from Co to P and Fe. The Co0.47Fe0.53P matrix with excellent conductivity and Fe phosphate that is stable on the surface of the catalyst are also helpful for the OER performance. In addition, the yolk–shell structure of Co0.47Fe0.53P increases the contact area between electrolyte and catalyst. These characteristics of Co0.47Fe0.53P greatly improve its OER performance. This optimized binary transition metal phosphide provides a new approach for the design of nonprecious-metal electrocatalysts.
Highly efficient hydrolysis of ammonia borane by anion (-OH, F-, Cl-)-tuned interactions between reactant molecules and CoP nanoparticles
Fu, Zi-Cheng,Xu, Yong,Chan, Sharon Lai-Fung,Wang, Wei-Wei,Li, Fang,Liang, Fei,Chen, Yong,Lin, Zhe-Shuai,Fu, Wen-Fu,Che, Chi-Ming
, p. 705 - 708 (2017)
The CoP nanoparticle catalyst had excellent catalytic activity and a short catalytic induction period in the presence of anions, and high sustainability in ammonia borane hydrolysis, with an initial turnover frequency of 72.2 mol(H2) mol(CoP)-1 min-1 at ambient temperature. This value is unprecedented for noble-metal-free catalytic systems.
The electrochemical confrontation between CoP microflake and Co3O4 microsphere via a similar synthesis process as anodes for lithium ion batteries
Guo, Qing,Ru, Qiang,Wang, Bei,Mo, Yudi,Wang, Zhen,Zhang, Peng,Hou, Xianhua,Hu, Shejun
, p. 910 - 916 (2017)
In this article, the synthesis of CoP microflake and Co3O4 microsphere via a simple two-step strategy is presented. Startlingly, electrochemical performance comparisons of as-prepared two compounds as anode materials for lithium ion batteries (LIBs) are investigated. CoP microflake depicts a prominent capacity retention and a long cycle life with a discharge capacity of 619.2 mAh/g at a high current density of 1000 mA/g after 800 cycles, while Co3O4 microsphere only shows a capacity of 93.1 mAh/g after 800 cycles under the current of 1000 mA/g. This work may offer a facile approach for the preparation of metal phosphides as promising anodes for LIBs.
Achieving the robust immobilization of CoP nanoparticles in cellulose nanofiber network-derived carbon: via chemical bonding for a stable potassium ion storage
Chen, Mingyang,Fan, Li-Zhen,Yang, Jiaqi,Zhao, Xudong,Zhou, Dan
, p. 44611 - 44623 (2020)
Potassium-ion batteries (KIBs) are currently being investigated as a potential alternative to lithium-ion batteries (LIBs) because of the natural abundance of K resources. Presently, it is crucial yet challenging to explore suitable anode materials for stable K-storage. Herein, a novel robust CoP-carbon composite with highly dispersed CoP nanoparticles (NPs) immobilized in natural cellulose nanofiber network (CNF)-derived carbon (denoted as CoP?CNFC) is synthesized via chemical bonding through a facile hydrothermal and subsequent in situ phosphidation approach. The designed structure can provide diverse merits, including fast reaction kinetics, sufficient active sites and effective accommodation for K+ insertion/extraction; thus, CoP?CNFC delivers desired electrochemical performance, including considerable reversible capacity, enhanced rate capability and excellent cycling stability. Additionally, the electrochemical reaction mechanism of CoP?CNFC was clearly revealed by ex situ characterizations and theoretical simulations of cyclic voltammetry (CV) and solid electrolyte interface (SEI) profiles based on first-principles calculations. The achieved deep elucidation of the reversible process of K+ insertion and extraction on the surface/interface of the active material during the discharge and charge states clearly highlights its significance for stable K-storage. This work promotes the facile design and deep understanding of nanostructured high-capacity electrodes of transition metal phosphates for rechargeable KIBs. This journal is
MXene supported Co: XAy (A = OH, P, Se) electrocatalysts for overall water splitting: Unveiling the role of anions in intrinsic activity and stability
Selvam, N. Clament Sagaya,Lee, Jooyoung,Choi, Gwan H.,Oh, Min Jun,Xu, Shiyu,Lim, Byungkwon,Yoo, Pil J.
, p. 27383 - 27393 (2019)
The development of efficient and stable bifunctional catalysts that outperform noble metal catalysts is a crucial task and an ongoing challenge for sustainable water electrolysis. In this work, large-size-exfoliated MXene sheets render a flat and flexible platform for the decoration of Co(OH)F, CoP and Co7Se8, allowing them to exhibit high electrocatalytic performances; thanks to the maximized surface area and conductivity. CoP/MXene shows enhanced oxygen evolution reaction (OER) activity, with substantially lower overpotential (η = 230 mV) at 10 mA cm-2 compared to those of IrO2 (300 mV). Furthermore, a hybrid bifunctional electrode (CoP/MXene//CoP/MXene) exhibits highly stable and efficient overall water splitting performance (1.56 V?10 mA cm-2) as compared to the benchmark electrode couple IrO2/C//Pt/C (1.62 V?10 mA cm-2) in alkaline solution. Furthermore, we elucidate the oxidation process of the anion components (P and Se) of the hybrid catalysts under OER conditions and verify their significant influence on the activity and stability. Notably, the surface oxidation of CoP/MXene results in a POx-enriched Co-OOH/CoP/MXene hybrid, which enables retention of consistent activity and stability. On the other hand, SeOx deposition on the Co-OOH/Co7Se8/MXene surface significantly deteriorates the activity and stability of the catalyst. These results not only highlight the insight on the correlation between oxidized anion species and the intrinsic activity of hybridized electrocatalysts but also impart the systematic synthetic design of MXene-supported catalysts with high water-splitting efficiency.
P-Type Cobalt Phosphide Composites (CoP-Co2P) Decorated on Titanium Oxide for Enhanced Noble-Metal-Free Photocatalytic H2Evolution Activity
Liang, Rong,Wang, Yanwen,Qin, Chao,Chen, Xuehua,Ye, Zhizhen,Zhu, Liping
, p. 3321 - 3330 (2021)
Nowadays, transition-metal phosphides have been reported to function well in photocatalytic water splitting and possess great potential to substitute traditional noble-metal cocatalysts in the future. Herein, p-type cobalt phosphide (CoP-Co2P) nanomaterials were synthesized by phosphating the solvothermally prepared Co(OH)2 nanoflowers at a low temperature (300 °C). Then, we combined the phosphides with commercial TiO2 through facile mechanical mixing to fabricate a useful noble-metal-free photocatalyst. The phosphating time that had an influence on the composition of phosphides was tuned, and 3 h was an ideal condition after comparison. The cobalt phosphide-modified TiO2 at the optimal weight percentage (nominal 0.5%) exhibited the highest photocatalytic hydrogen rate of approximately 824.5 μmol g-1 h-1 under simulated sunlight irradiation, which was nearly equal to 160 times that of bare TiO2 and 1.7 times that of single CoP-modified TiO2. The CoPx/TiO2 heterojunction interfaces were studied using photoluminescence (PL), time-resolved PL, and photoelectrochemical methods, which revealed that the effective charge separation and transfer accelerated by the built-in electric field of p-n junction contributed significantly to the photocatalytic performance.
AMBIENT PRESSURE SYNTHESIS, PROPERTIES, AND STRUCTURE REFINEMENTS OF VP4 AND CoP2.
Jeitschko,Floerke,Scholz
, p. 320 - 326 (1984)
The previously reported compounds VP//4 and CoP//2, prepared at high pressure, were synthesized in well-crystallized form at ambient pressure by reaction of the elemental components in the presence of iodine. Their structures were refined from single-crystal X-ray diffractometer data to conventional residuals of R equals 0. 033 for VP//4(CrP//4 type structure, 11 variables, 815 F values) and R equals 0. 019 for CoP//2 (arsenopyrite structure, 14 variables, 932 F values). VP//4 is paramagnetic and a metallic conductor. CoP//2 is a diamagnetic semiconductor with an activation energy of 0. 34 ev. Chemical bonding and potential displacive phase transitions of these compounds are discussed.
An iron-doped cobalt phosphide nano-electrocatalyst derived from a metal-organic framework for efficient water splitting
Lin, Can,Wang, Pengyan,Jin, Huihui,Zhao, Jiahuan,Chen, Ding,Liu, Suli,Zhang, Chengtian,Mu, Shichun
, p. 16555 - 16561 (2019)
The development of hydrogen energy relies to a large extent on the electrocatalysts that are highly efficient and widely sourced. Although transition metal phosphides (TMPs) have made great achievements in reducing the overpotential of hydrogen evolution reaction (HER), improving oxygen evolution reaction (OER) performance that is relatively lagging in view of relatively large overpotentials and high kinetics energy barriers is yet to be achieved. Herein, we propose an extremely convenient and practical approach to prepare iron-doped cobalt phosphide nanoparticles (Fe-CoxP NPs) via a one-step method by introducing an iron element in the in situ synthesis of a metal-organic framework (ZIF-67) and then subjecting to a phosphate treatment. The as-obtained Fe-CoxP showed an excellent OER and acceptable HER activities. In particular, for OER, the optimized Fe-doped CoxP (Fe0.27Co0.73P) exhibits an ultra-low overpotential of 251 mV at a current density of 10 mA cm-2, a negligible electrocatalytic degradation after 3000 CV cycles, and time over 40 h-reliant current density stability. When employed as cathode and anode electrodes in water splitting, the current density of 10 mA cm-2 can be achieved at a potential of 1.68 V. Our facile synthetic strategy and innovative ideas are undoubtedly beneficial to the design and construction of advanced water-splitting electrocatalysts.
Photocatalytic oxidation of arylalcohols to aromatic aldehydes promoted by hydroxyl radicals over a CoP/CdS photocatalyst in water with hydrogen evolution
Xu, Yong,Zeng, Ling-Zhen,Fu, Zi-Cheng,Li, Cong,Yang, Zhi,Chen, Yong,Fu, Wen-Fu
, p. 2540 - 2545 (2018)
Cobalt phosphide (CoP) combined with CdS was employed as a photocatalyst to oxidize arylalcohols into aromatic aldehydes or ketones in water. This was accompanied by the reduction of water, and the quantitative yield of hydrogen evolution was much higher than the chemical equivalent of hydrogen gas. Electron spin resonance spectroscopy and quenching experiments demonstrated that hydroxyl free radicals, originating from water splitting, promoted the oxidation of arylalcohols, while the holes in the valence band of the photocatalyst were reduced by the -OH and organic substrates. The overall reaction generates high-value-added organics. This photocatalytic reaction is atom-economical, in accordance with the concept of sustainable development.
Template-assisted synthesis of CoP nanotubes to efficiently catalyze hydrogen-evolving reaction
Du, Hongfang,Liu, Qian,Cheng, Ningyan,Asiri, Abdullah M.,Sun, Xuping,Li, Chang Ming
, p. 14812 - 14816 (2014)
For the first time, we demonstrate a template-assisting synthesis to make CoP nanotubes (CoP NTs) through low-temperature phosphidation of Co salt inside a porous anodic aluminium oxide template followed by dilute HF etching. Such CoP NTs exhibit excellent hydrogen-evolution catalytic activity and durability in an acidic medium, which is superior to their nanoparticle counterparts, with a Faradaic yield of nearly 100%. The fundamental insight for the catalytic enhancement mechanism is also explored. the Partner Organisations 2014.
Facile Synthesis of Hierarchical Hollow CoP?C Composites with Superior Performance for Sodium and Potassium Storage
Chou, Shu-Lei,Dou, Shi-Xue,Gu, Qinfen,Hu, Zhe,Jin, Huile,Li, Lin,Liang, Yaru,Liu, Qiannan,Liu, Yong,Lu, Huanming,Wang, Shun,Zou, Chao
, p. 5159 - 5164 (2020)
Hierarchical hollow CoP and carbon composites were obtained through a facile synthetic method, where carbonization and phosphorization of the precursor were completed within one single step. The composites are composed of hollow CoP?C spheres, which are further made up of CoP nanoparticles with a thin outer carbon layer. Electrochemical performances of the prepared CoP?C composites as anodes for sodium and potassium storage were evaluated and compared. In situ TEM, in situ synchrotron XRD, and DFT calculations were conducted to study the structural evolution and the interaction between Na/K and CoP during cycling processes. Benefiting from the synergistic effect of conductive carbon layer and hierarchical hollow structure, the as-prepared CoP?C composites demonstrate superior sodium and potassium storage capability as anode materials for rechargeable batteries.
Highly active electrocatalysis of the hydrogen evolution reaction by cobalt phosphide nanoparticles
Popczun, Eric J.,Read, Carlos G.,Roske, Christopher W.,Lewis, Nathan S.,Schaak, Raymond E.
, p. 5427 - 5430 (2014)
Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H2SO4, pH 0.3). Uniform, multi-faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm-2 mass loading) produced a cathodic current density of 20 mA cm-2 at an overpotential of -85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H 2SO4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions. CoP is therefore amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date. One step closer to Pt: Nanoparticles of cobalt phosphide (CoP) catalyze the hydrogen evolution reaction with high activity and stability under strongly acidic conditions. Its electrocatalytic performance places CoP amongst the best Earth-abundant alternatives to platinum.
Delicate Control on the Shell Structure of Hollow Spheres Enables Tunable Mass Transport in Water Splitting
Hou, Ping,Li, Dan,Yang, Nailiang,Wan, Jiawei,Zhang, Chunhui,Zhang, Xiqi,Jiang, Hongyu,Zhang, Qinghua,Gu, Lin,Wang, Dan
, p. 6926 - 6931 (2021)
In the study of structure–property relationships for rational materials design, hollow multishell structures (HoMSs) have attracted tremendous attention owing to the optimal balance between mass transfer and surface exposure. Considering the shell structure can significantly affect the properties of HoMSs, in this paper, we provide a novel one-step strategy to continually regulate the shell structures of HoMSs. Through a simple phosphorization process, we can effectively modify the shell from solid to bubble-like and even duplicate the shells with a narrow spacing. Benefitting from the structure merits, the fabricated CoP HoMSs with close duplicated shells can promote gas release owing to the unbalanced Laplace pressure, while accelerating liquid transfer for enhanced capillary force. It can provide effective channels for water and gas and thus exhibits a superior electrocatalytic performance in the hydrogen and oxygen evolution reaction.
Intracell Hydrogen Adsorption–Transmission in a Co2P Solid Hydrogen-Storage Material
Bao, Di,Gao, Peng,Li, Chenliang,Wu, Guoxun,Wang, Yanbo,Chen, Yujin,Zhou, Han,Yang, Piaoping
, p. 3371 - 3375 (2016)
Co2P nanoparticles, obtained by a simple mechanical ball-milling treatment, have been shown to undergo a new hydrogen adsorption–transmission process called intracell Kubas-enhanced adsorption, which results in an improved hydrogen-storage capacity. It is found that in this intracell Kubas-enhanced adsorption process hydrogen is firstly adsorbed by the Co atoms in Co2P through a Co···H interaction and activated. It is then spilt over to the P atoms in Co2P accompanied by the formation of a P–H bond, which has a lower bonding energy. This adsorption–transmission process is unambiguously proved by a detailed analysis of X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), cyclic voltammetry (CV), and quantum chemical calculation results.
Contributions on thermal behaviour and crystal chemistry of anhydrous phosphates. XXXIV [1]: Oxygen equilibrium pressures in ternary systems M/P/O (M = Co, Ni) and heats of formation of anhydrous cobalt(II) and nickel(II) phosphates
Blum, Matthias,Teske, Klaus,Glaum, Robert
, p. 1709 - 1717 (2003)
Oxygen equilibrium pressures have been measured in the temperature range 800°C to 1000°C by coulometric/potentiometric techniques for several equilibrium regions in the ternary systems M/P/O (M = Co, Ni). In both systems oxygen coexistence pressures of th
1D Composite Nanorods of Cobalt Phosphide-Cobalt Sulfide with Improved Electrocatalyst Performance
Sidek, Haslinda Binti Mohd,Jin, Xiaoyan,Islam, Md. Shahinul,Hwang, Seong-Ju
, p. 6099 - 6104 (2019)
Efficient electrocatalysts of cobalt phosphide-cobalt sulfide 1D composite nanorods for hydrogen evolution reaction (HER) are synthesized by heat-treatment of cobalt phosphide nanorod under CS2 flow. The reaction of cobalt phosphide with CS2 molecule leads to the formation of CoP?CoS composite with the maintenance of original 1D nanorod morphology. In comparison with the pristine CoP nanorod, the CoP?CoS composite nanorod shows much higher HER electrocatalytic activity with much lower overpotential, highlighting the beneficial effect of composite formation with metal sulfide on electrocatalyst performance of metal phosphide. The composite formation with CoS domain results in the remarkable enhancement of HER kinetics, electrochemical active surface area, and charge transfer kinetics, which is mainly responsible for the enhanced electrocatalytic activity of composite nanorod. The present study underscores that hybridization with metal sulfide can provide an efficient methodology to improve the electrocatalyst functionality of metal phosphide.
General Synthesis of Multishell Mixed-Metal Oxyphosphide Particles with Enhanced Electrocatalytic Activity in the Oxygen Evolution Reaction
Guan, Bu Yuan,Yu, Le,Lou, Xiong Wen David
, p. 2386 - 2389 (2017)
We report a general approach for the synthesis of multishell mixed-metal oxyphosphide particles. Seven-layer Mn-Co oxide particles were first prepared by thermal treatment of Mn-Co coordination polymer precursors. Afterwards, these multishell Mn-Co oxide particles were further transformed into multishell Mn-Co oxyphosphide particles through a phosphidation reaction. This approach is very versatile and can be applied to synthesize other multishell mixed-metal oxyphosphide particles with different compositions. By applying a constant electrochemical potential, these multishell Mn-Co oxyphosphide particles can be activated to produce Mn-Co oxide/hydroxide species in their nanoshells and then show greatly enhanced electrocatalytic activity in the oxygen evolution reaction (OER).
MOF-derived Mn doped porous CoP nanosheets as efficient and stable bifunctional electrocatalysts for water splitting
Li, Yinle,Jia, Baoming,Chen, Boyuan,Liu, Qinglin,Cai, Mengke,Xue, Ziqian,Fan, Yanan,Wang, Hai-Ping,Su, Cheng-Yong,Li, Guangqin
, p. 14679 - 14685 (2018)
Searching for highly active and stable bifunctional electrocatalysts for overall water splitting, e.g., for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is dominating in terms of bringing future renewable energy storage and conversion processes to reality. In this work, a kind of two-dimensional ultrathin manganese (Mn) doped polyhedral cobalt phosphide (Mn-CoP) has been synthesized via the etching-carbonization-phosphidation of Co-centered metal-organic frameworks. The as-prepared porous Mn-CoP nanosheets had a larger specific surface area and higher porosity, furnishing them with more plentiful catalytically active sites than their counterpart hollow CoP and Mn-CoP nanoparticles, and thus showed much better electrocatalytic activity for both HER and OER in acidic and alkaline media. In addition, the Mn-CoP nanosheets also demonstrated excellent durability after long-term operation. These high performances are attributed to the synergistic effects of the CoP nanosheets with intrinsic activity, the graphitic carbon and the controllable electronic structure doped by Mn and N elements. This synthetic methodology of using a classical MOF as a precursor to build a new 2D sheet-like composite may create opportunities to search for highly efficient and robust non-precious metal catalysts for energy-related reactions.
Cobalt nickel phosphide nanoparticles decorated carbon nanotubes as advanced hybrid catalysts for hydrogen evolution
Pan, Yuan,Chen, Yinjuan,Lin, Yan,Cui, Peixin,Sun, Kaian,Liu, Yunqi,Liu, Chenguang
, p. 14675 - 14686 (2016)
Exploring new hybrid catalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is important for various renewable energy applications. However, the design and synthesis of such catalysts are still challenging. Herein, we focus on the development of a series of hybrid materials consisting of cobalt nickel phosphide nanoparticles (NPs) decorated carbon nanotubes (Co2-xNixP/CNTs) as efficient catalysts for enhanced HER catalytic activity. All the X-ray spectra including X-ray diffraction, X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy demonstrate that the crystalline phase structure, valence and coordination environment of hexagonal Ni2P are changed with increasing Co atoms. Electrochemical measurements show that the Co2-xNixP/CNT hybrids exhibit high activity and stability for the HER in acidic solution. The as-synthesized Co1.6Ni0.4P/CNT hybrid exhibits the highest electrocatalytic activity with low onset overpotential (36.1 mV), a small Tafel slope (46.7 mV dec-1), a much larger exchange current density (1.86 × 10-5 A cm-2), lower HER activation energy (57.3 kJ mol-1), and good stability. Such enhanced catalytic activity originates from the introduction of Co and strong synergistic effects between CNTs and Co2-xNixP. Meanwhile, density functional theory calculations also confirm that the higher HER catalytic activity of the Co2-xNixP/CNTs can be attributed to the splendid migratory aptitude of adsorbed single H atoms and the lower energy barrier for H2 formation after the introduction of Co atoms. The as-synthesized Co2-xNixP/CNT hybrid catalysts have great potential practical application in water splitting.
Synthesis, characterization, and hydrotreating activity of several iron group transition metal phosphides
Wang, Xianqin,Clark, Paul,Oyama, S. Ted
, p. 321 - 331 (2002)
A series of iron, cobalt, and nickel metal phosphides of chemical formula Fe2P, CoP, and Ni2P with specific surface areas of around 3 m2 g-1 were synthesized by means of temperature-programmed reduction (TPR) of the corresponding phosphates. These phosphides were also successfully prepared in dispersed form on a silica support (90 m2 g-1) for use as catalysts. The phase purity of these materials was established by X-ray diffraction (XRD), and surface properties were determined by N2 BET specific surface area (Sg) measurements and CO uptake determinations. The activity of the silica-supported catalysts in hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) was evaluated in a three-phase trickle-bed reactor using a model liquid feed containing 2000 ppm nitrogen as quinoline, 3000 ppm sulfur as dibenzothiophene, 500 ppm oxygen as benzofuran, 20 wt% aromatics as tetralin, and balance aliphatics as tetradecane. The reactivity study showed that the HDS activity sequence for the three samples was Ni2P/SiO2>CoP/SiO2>Fe2P/ SiO2, while the HDN activity followed the sequence CoP/SiO2>Ni2P/SiO2>Fe2P/ SiO2. Compared with a commercial Ni-Mo-S/γ-Al2O3 catalyst, Ni2P/SiO2 had a higher HDS activity (90 vs 76%), but a lower HDN activity (14 vs 38%), based on equal sites loaded in the reactor. The sites were determined by CO chemisorption for the phosphide and low-temperature O2 chemisorption for the sulfide. XRD and X-ray photoelectron spectroscopy characterizations of the spent catalysts indicated that the Ni2P/SiO2 catalyst was tolerant of sulfur.
Highly efficient hydrogen evolution from water electrolysis using nanocrystalline transition metal phosphide catalysts
Wu, Weiming,Wu, Xiao-Yuan,Wang, Sa-Sa,Lu, Can-Zhong
, p. 39291 - 39295 (2018)
Nanocrystalline transition metal phosphides (CoP and Ni2P) were successfully synthesized by a simple calcination method by using transition metal hydroxides and NaH2PO2 as raw materials. Their catalytic activities for the hydrogen evolution from water electrolysis were evaluated with silicotungstic acid as an electron-coupled-proton buffer, whereby hydrogen and oxygen could be produced separately. It was found that the CoP sample showed higher catalytic activity (32 mmol min?1 g?1) and good stability (12 h) as compared to the Ni2P sample, and its catalytic activity could rival that of the commercial Pt/C catalyst. The electrochemical results revealed that CoP had high cathodic current and small charge transfer resistance, which further suggested it was indeed an efficient noble metal-free catalyst for hydrogen evolution from water electrolysis.
Conditions for the Electrochemical Synthesis of the CoPn3 (Pn = P, As, Sb) Skutterudites
DeMattei,Watcharapasorn,Feigelson
, p. D109-D111 (2001)
The binary pnictide skutterudites, CoPn3 (Pn = P, As, Sb), have been successfully synthesized for the first time by molten salt electrolysis. The melt for depositing CoP3 contained CoO and (NaPO3)3, and graphite
Cobalt phosphide supported by two-dimensional molybdenum carbide (MXene) for the hydrogen evolution reaction, oxygen evolution reaction, and overall water splitting
Lin, Zongshan,Liu, Shilong,Liu, Yonggang,Liu, Zhe,Lu, Xiaoxing,Tang, Zhenghua,Tian, Yong,Wan, Rendian,Zhang, Shuidong,Zhang, Xiaofeng
, p. 21259 - 21269 (2021)
Developing a low cost, high performance, and durable bifunctional catalyst to boost the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for water splitting is a critical yet challenging task. Transition metal phosphides have been identified as promising dual functional catalysts recently. Herein, we report a facile strategy to construct a heterostructure catalyst by integrating cobalt phosphide with molybdenum carbide (MXene). The CoP/Mo2CTx(T is the surface terminal group) catalyst exhibited good HER activity with an overpotential of 78 mV at a current density of 10 mA cm?2, close to that of the Pt/C benchmark, and its OER performance is markedly better than that of the RuO2benchmark, evidenced by a very small overpotential of 260 mV at 10 mA cm?2in 1 M KOH. Impressively, when employed for overall water splitting, CoP/Mo2CTxalso outperformed the Pt/C + RuO2combination with a voltage of 1.56 V @ 10 mA cm?2. Density functional theory (DFT) calculations revealed that CoP/Mo2CTxhas appropriate water adsorption especially the optimal H* adsorption free energy (ΔGH*), and the Mo2C MXene support can significantly increase the total density of states and downshift the d-band center for the HER, while for the OER, multiple characterization techniques of CoP/Mo2CTxpost the OER test show that CoP in the catalyst can be transformed into Co-OOH during the electrocatalytic process. This study can provide a pathway for the design and fabrication of MXene-supported noble-metal-free bifunctional catalysts toward practical water splitting and energy conversion.
Needle-like cobalt phosphide arrays grown on carbon fiber cloth as a binder-free electrode with enhanced lithium storage performance
Cai, Jianxin,Li, Chao,Yang, Zhenyu,Yu, Ji,Zhang, Ze,Zhu, Peipei
, p. 154 - 157 (2021)
Cobalt phosphide (CoP) is a promising anode candidate for lithium-ion batteries (LIBs) due to its high specific capacity and low working potential. However, the poor cycling stability and rate performance, caused by low electrical conductivity and huge volume variation, impede the further practical application of CoP anode materials. Herein, we report an integrated binder-free electrode featuring needle-like CoP arrays grown on carbon fiber cloth (CC) for efficient lithium storage. The as-prepared CoP/CC electrode integrates the advantages of 1D needle-like CoP arrays for efficient electrolyte wettability and fast charge transportation, and 3D CC substrate for superior mechanical stability, flexibility and high conductivity. As a result, the CoP/CC electrode delivers an initial specific capacity of 1283 mA h/g and initial Coulombic effeciencies of 85.4%, which are much higher than that of conventional CoP electrode. Notably, the CoP/CC electrode shows outstanding cycling performance up to 400 cycles at 0.5 A/cm2 and excellent rate performance with a discharge capacity of 549 mA h/g even at 5 A/cm2. This work demonstrates the great potential of integrated CoP/CC hybrid as efficient bind-free and freestanding electrode for LIBs and future flexible electronic devices.
Magnetic Properties of Eu(Co1?xNix)2P2
Haraguchi, Yuya,Katori, Hiroko Aruga,Kobayashi, Yoshio,Nakamura, Jin,Nakamura, Raito,Ohta, Hiroto
, (2022/01/28)
Solid solution 122-type compounds, Eu(Co1?xNix)2P2, were investigated using crystallographic, magnetic, and 151Eu M?ssbauer effect measurements. A discontinuous isostructural phase transition from the uncollapsed tetragonal (ucT) to collapsed tetragonal (cT) structure was observed around x = 0.3. In the ucT region, Eu was divalent and showed helical magnetism of the Eu sublattice as well as at x = 0. However, in the cT region, Eu had an intermediate valence (+2.2 at 300 K) and showed paramagnetic behavior. The temperature dependence of the Eu valence was in good agreement with the Inter-Configurational Fluctuation (ICF) model. The Eu sublattice lost its magnetic order, but the Co=Ni sublattice exhibited itinerant ferromagnetism around 150 K. In addition, the net magnetization was lost due to the antiferromagnetic-like reorientation of the Co=Ni spins below 70 K. This magnetic structure was not observed in other 122-compounds and was a novel magnetic phase.
