12134-02-0Relevant academic research and scientific papers
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.
Structural control of electroless-plated magnetic recording media by underlayers
Matsubara,Toda,Sakuma,Homma,Osaka,Yamazaki,Namikawa
, p. 753 - 756 (1989)
The structural control of electroless-plated CoP film was investigated using underlayers of electroless-plated CoNiMnP and CoNiP films. The CoNiMnP film showed a high degree of orientation of the hcp Co c-axis normal to the film plane, whereas the CoNiP film hardly showed any preferred orientation. The CoP film plated onto the CoNiMnP underlayer showed a high degree of preferred orientation, while the CoP film plated onto the CoNiP underlayer showed a low degree of preferred orientation. Thus, the microstructure of the CoP film is clearly influenced by the underlayer structure. In the case of the CoP film onto the CoNiMnP underlayer, an epitaxial-like growth was observed up to a thickness of 0.25 μm, and this reduced to the intrinsic microstructure at a thickness of 0.5 μm. Recording characteristics were measured on the 5 in. flexible disks, fabricated by plating the high-oriented CoP film or the low-oriented CoP film with a ring-type head of a commercial VHS video head. Perpendicular recording was performed on the high-oriented CoP film to demonstrate the best characteristics. The use of an oriented underlayer is thus confirmed to be a useful method of controlling the structure of the magnetic film in addition to controlling the bath plating parameters.
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.
Hydrogen on Cobalt Phosphide
Delley, Murielle F.,Wu, Zishan,Mundy, M. Elizabeth,Ung, David,Cossairt, Brandi M.,Wang, Hailiang,Mayer, James M.
, p. 15390 - 15402 (2019)
Cobalt phosphide (CoP) is one of the most promising earth-abundant replacements for noble metal catalysts for the hydrogen evolution reaction (HER). Critical to HER is the binding of H atoms. While theoretical studies have computed preferred sites and energetics of hydrogen bound to transition metal phosphide surfaces, direct experimental studies are scarce. Herein, we describe measurements of stoichiometry and thermochemistry for hydrogen bound to CoP. We studied both mesoscale CoP particles, exhibiting phosphide surfaces after an acidic pretreatment, and colloidal CoP nanoparticles. Treatment with H2 introduced large amounts of reactive hydrogen to CoP, ca. 0.2 H per CoP unit, and on the order of one H per Co or P surface atom. This was quantified using alkyne hydrogenation and H-atom transfer reactions with phenoxy radicals. Reactive H atoms were even present on the as-prepared materials. On the basis of the reactivity of CoP with various molecular hydrogen donating and accepting reagents, the distribution of binding free energies for H atoms on CoP was estimated to be roughly 51-66 kcal mol-1 (δG°H 0 to -0.7 eV vs H2). Operando X-ray absorption spectroscopy gave preliminary indications about the structure of hydrogenated CoP, showing a slight lattice expansion and no significant change of the effective nuclear charge of Co under H2-flow. These results provide a new picture of catalytically active CoP, with a substantial amount of reactive H atoms. This is likely of fundamental relevance for its catalytic and electrocatalytic properties. Additionally, the approach developed here provides a roadmap to examine hydrogen on other materials.
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.
Anion engineering of hierarchical Co-A (A = O, Se, P) hexagrams for efficient electrocatalytic oxygen evolution reaction
Liang, Zuozhong,Yang, Chenxi,Zhang, Wei,Zheng, Haoquan,Cao, Rui
, p. 3241 - 3244 (2021)
Water electrolysis is considered to be an effective and promising technology to make high-purity H2, however, the relationship between anion species and catalytic performance of electrocatalysts is still not completely clear. Herein, we report an anion engineering strategy to tune electrocatalytic water oxidation activity for Co-based materials. Novel hierarchical Co-based oxide/selenide/phosphide (Co-A, A = O, Se, P) hexagrams have been chosen as model materials. Electrochemical results and theoretical calculations reveal that the electron configuration, the electrical conductivity, and the oxidation potential of Co element in Co-A hexagrams could be moderated by the substitution of P atoms, which leads to the superior OER performance. Particularly, Co-P hexagram displays a low overpotential (η = 269 mV) at j = 10 mA/cm2 for the oxygen evolution reaction (OER) compared to Co-O hexagram (η = 399 mV) and Co-Se hexagram (η = 347 mV). This work is of great importance in understanding coordination atoms (O, Se and P) induced electrocatalytic properties of hierarchical Co-based materials.
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.
Facile synthesis of various highly dispersive CoP nanocrystal embedded carbon matrices as efficient electrocatalysts for the hydrogen evolution reaction
Li, Mian,Liu, Xiaotian,Xiong, Yueping,Bo, Xiangjie,Zhang, Yufan,Han, Ce,Guo, Liping
, p. 4255 - 4265 (2015)
In order to promote the hydrogen evolution reaction (HER) catalytic efficiency of cobalt phosphide (CoP) and then construct efficient HER catalysts, a facile procedure has been adopted to prepare tiny CoP nanoparticle (NP) embedded carbon matrices without using any extreme conditions and harmful organic reagents or surfactants. Meanwhile, in order to explore the influence of structures of carbon matrices on preventing the free growth of CoP NPs and enhancing the HER catalytic efficiency of the CoP-carbon catalysts, imporous reduced graphene oxide (RGO), macroporous carbon (MPC), mesoporous carbon vesicles (MCVs) and ordered mesoporous carbon (OMC) were used for preparing CoP-carbon HER catalysts. SEM and TEM measurements show that size-controlled CoP NPs indeed grew more uniformly on the OMC frameworks than those on MCVs, MPC and RGO. As expected, the HER is catalyzed more efficiently on CoP-OMC accompanied by a small onset potential of -77.74 mV vs. RHE, a low Tafel slope of 56.67 mV dec-1, a small over-potential value of 112.18 mV at 10 mA cm-2, and the outstanding long-term stability. These results show that CoP-OMC inherently exhibits better HER catalytic activity than other CoP-based catalysts in acidic electrolytes. Such excellent performances are attributed to the synergistic effect of the highly catalytic sites provided by the uniformly dispersed and size-controlled CoP NPs embedded on OMC, excellent proton transport efficiency, and improved electron transport with a high electron transfer rate. Our results provide useful information that the mesoporous conductive matrices could be applied to greatly improve the HER catalytic efficiency of various HER catalytically active centers. This journal is
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
Oxidation does not (always) kill reactivity of transition metals: Solution-phase conversion of nanoscale transition metal oxides to phosphides and sulfides
Muthuswamy, Elayaraja,Brock, Stephanie L.
, p. 15849 - 15851 (2010)
Unexpected reactivity on the part of oxide nanoparticles that enables their transformation into phosphides or sulfides by solution-phase reaction with trioctylphosphine (TOP) or sulfur, respectively, at temperatures of ≥370 °C is reported. Impressively, s
