JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Jingyun Wang,Wei Li,Xiaofang Chen,Aisheng Huang
Transition metal phosphides are considered as promising alternatives to noble-metal based electrocatalysts for water splitting due to their bifunctional catalytic activity. The modulation of morphology and electronic structure is an efficient strategy to improve the mass transport and electronic conductivity of metal phosphides, but still faces a great challenge to achieve this conjoint regulation. Herein, a facile Zn-doped strategy was developed to synthesize cobalt phosphide (CoP) catalyst with thickness-controlled porous nanosheet structure. At the current density of 10 mA cm −2 , the optimized Zn 0.1 -CoP catalyst delivers an overpotentials of 290 mV and 98 mV for OER and HER , respectively. The cell voltage for the overall water splitting is 1.57 V to reach the current density of 10 mA cm −2 , outperforming the counterparts of noble metal-based Pt/C and IrO 2 catalysts. The density functional theory (DFT) calculations reveal that Zn doping can effectively improve the conductivity and regulate the electronic structure of CoP, thus resulting in fast charge transfer transport and reduced energy barrier of the rate-determining step. This work provides a favorable strategy for the rational design of bifunctional catalysts with high-performance for overall water splitting.
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高影响因子
ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Lin Zhu,Yan Zhang,Baoli Wang,Ruyi Zou,Yuhao Huang,Wei Sun
Equivalent circuit model (ECM) is one of the most commonly used tools in electrode process analysis such as hydrogen evolution reaction (HER) process in electrochemical impedance spectroscopy experiment. This work attempts to analyze dynamic element values of ECM of cobalt phosphide-boron nitride doped carbon (CoP/BN-C) in HER process during linear sweep voltammetric test with the help of Kalman filter algorithm. Tafel slopes of CoP/BN-C in alkaline solution and in seawater are close (∼106 mV•dec −1 ) with the overpotential ( η ) of 154 mV and 545 mV to drive a current density of 10 mA•cm −2 , respectively. Polarization resistance (R pol ) of CoP/BN-C calculated from system identification reaches 2.21 kΩ in seawater, which is about twice of the maximum value in alkaline solution. Power analysis can also certificate the difference of catalytic efficiency in different electrolyte. The potential position of the maximum R pol is close to the position of onset potential. This contribution provides a practical and effective strategy to obtain R pol from LSV curves and presents a two-dimensional image composed of η and R pol , which may supplement more information on catalytic activity of HER process in various environments.
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ChemElectroChem
·
2022
·Vol. 9
·期 3
·e202101482
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IF 4.782
Hao Cui,Min Jiang,Gang Tan,Jianping Xie,Pengfei Tan,Jun Pan
Graphical Ru-CoP/CC electrocatalyst for hydrogen evolution was synthesized through simple in-situ hydrothermal and gas phosphatized treatments, which only needs 44 mV to reach 10 mA cm −2 , exceeding many reported electrocatalysts. Meanwhile, the reason and the result of electrons redistribution after Ru doping were deeply investigated. Exploring highly efficient, durable and low-cost catalysts for hydrogen evolution reaction (HER) is crucial to promoting the development of electrochemical water splitting systems but remains challenging. In this work, the Ru-modified CoP nanoflakes on carbon clothes (Ru-CoP/CC) are fabricated via an in-situ hydrothermal method, followed by low-temperature phosphatized treatments. According to X-ray photoelectron spectroscopy (XPS) measurements, the Ru doping induces the electron deviation from Ru to Co−P, and makes Co ions be an electron-rich state. It is revealed that the introduction of Ru can effectually reconstruct the electron coordination environment of Co−P. The resultant Ru-CoP/CC catalyst shows outstanding HER performance with an ultralow overpotential of 45 mV at 10 mA cm −2 . Moreover, the obtained catalyst exhibits long-term durability at 20 mA cm −2 for 20 h in the alkaline solution. This work opens a new avenue to lower the usage of noble metal in electrocatalyst and helps to developing a high-performance electrocatalyst for HER.
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ACS Omega
·
2022
·
IF 4.132
Linyi Zhang,Yu Chen,Guangsheng Liu,Zhen Li,Song Liu,Santosh K. Tiwari,Oluwafunmilola Ola,Bingyan Pang,Nannan Wang,Yanqiu Zhu
Development of a low cost, high activity, and stable nonprecious metal bifunctional catalyst for electrocatalytic water cracking is a hot topic and big challenge. In this paper, we prepared a nitrogen-doped carbon nanotube (NCNT)-enhanced three-dimensional self-supported electrocatalyst with CoP and Co2P coexistence by a two-step strategy of high-temperature carbonization and low-temperature phosphorylation. Furthermore, the induced three-dimensional carbon network skeleton facilitates rapid charge transfer. In addition, the active sites of the carbon foam (CF) are greatly increased by the construction of hollow structures. As a bifunctional electrocatalyst, CoP/Co2P/NCNT@CF exhibited excellent catalytic activity for both hydrogen evolution reaction and oxygen evolution reaction in alkaline media, requiring low overpotentials of 133 and 289 mV to obtain a current density of 10 mA cm–2, respectively. Additionally, the synthesized catalysts also exhibit good long-term stability, maintaining high catalytic activity after 20 h of continuous operation. We also confirmed the main driving force to improve the electron transfer between the heterostructures of Co and P by XPS spectra. The excellent electrocatalytic performance can be attributed to the close synergy between the highly active CoP/Co2P/NCNT and CF. This study provides a new strategy for the design of highly active bifunctional self-supporting electrocatalysts.
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高影响因子
Engineering
·
2022
·
IF 12.834
Chen Hu,Yanjie Hu,Aiping Chen,Xuezhi Duan,Hao Jiang,Chunzhong Li
Tin phosphides are attractive anode materials for ultrafast lithium-ion batteries (LIBs) because of their ultrahigh Li-ion diffusion capability and large theoretical-specific capacity. However, difficulties in synthesis and large size enabling electrochemical irreversibility impede their applications. Herein, an in situ catalytic phosphorization strategy is developed to synthesize SnP/CoP hetero-nanocrystals within reduced graphene oxide (rGO)-coated carbon frameworks, in which the SnP relative formation energy is significantly decreased according to density functional theory (DFT) calculations. The optimized hybrids exhibit ultrafast charge/discharge capability (260 mA·h·g −1 at 50 A·g − 1 ) without capacity fading (645 mA·h·g − 1 at 2 A·g − 1 ) through 1500 cycles. The lithiation/delithiation mechanism is disclosed, showing that the 4.0 nm sized SnP/CoP nanocrystals possess a very high reversibility and that the previously formed metallic Co of CoP at a relatively high potential accelerates the subsequent reaction kinetics of SnP, hence endowing them with ultrafast charge/discharge capability, which is further verified by the relative dynamic current density distributions according to the finite element analysis.
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APPLIED THERMAL ENGINEERING
·
2022
·
IF 6.465
Zhenghao Jin,Shuhong Li,Runfa Zhou,Mengkai Xu,Weixue Jiang,Kai Du
Adding nanoparticles can enhance the mass and heat transfer of basic fluid, improving the coefficient of performance(COP) of the absorption refrigeration system(ARS). However, there are few experimental studies on the effects of absorption pressure and temperature on the absorption performance of nanofluid in an actual ARS. Therefore, the TiO 2 nanoparticles are added to the NH 3 - H 2 O – LiBr working fluid. The difference in ammonia mass fraction between the inlet and outlet solution of the absorber (Δ ε ' a ) is compared with when the solution is absorbed saturated (Δ ε a ). The results indicate that the Δ ε ' a and system COP increase when the absorption temperature decreases, the absorption pressure increases, or the TiO 2 mass fraction increases. The ratio Δ ε ' a /Δ ε a is used to evaluate the absorption efficiency of the nanofluid. The positive effects of nanofluid on the absorption efficiency and COP slightly increase when absorption temperature increases, but decrease when the absorption pressure is greater than 0.31 MPa. For all of our test groups, the greatest improvement in absorption efficiency is 85 %, and the largest improvement in COP is 13.7 %.
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Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 13
·8561-8567
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IF 12.732
Shuo Geng,Fenyang Tian,Menggang Li,Xin Guo,Yongsheng Yu,Weiwei Yang,Yanglong Hou
Tailoring the d-band center is an effective method to promote the hydrogen evolution reaction (HER) activity of electrocatalysts. Herein, we demonstrate that the d-band center can be tuned through a hole-creating method to enhance pH-universal HER activity using CoP as a basic platform. The density functional theory (DFT) calculation reveals that the d-band center and the valence electron number of Co sites around the holes are upshifted, which boosts H adsorption. In addition, introducing holes into the nanosheets of CoP can optimize the ΔGH* of the Co atoms around the holes. Inspired by the DFT results, a soft template method was developed to synthesize hole-rich CoP nanosheets. With the advantages of hole-rich and unique nanosheet features, the hole-rich CoP nanosheets show low HER overpotentials with only 84 and 94 mV to achieve a current density of 10 mA cm−2 in both acidic and alkaline media, better than that of the other dimensional counterparts. In addition, the hole-rich CoP nanosheets also show satisfactory stability after long-term HER tests. This strategy of regulating the d-band center is expected to be extended to other transition metal phosphide electrocatalysts for enhancing the HER performance.
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Nanomaterials
·
2021
·Vol. 11
·期 6
·1450
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IF 5.076
Yanfang Liu,Yong Li,Qi Wu,Zhe Su,Bin Wang,Yuanfu Chen,Shifeng Wang
Electrolysis of water to produce hydrogen is crucial for developing sustainable clean energy and protecting the environment. However, because of the multi-electron transfer in the oxygen evolution reaction (OER) process, the kinetics of the reaction is seriously hindered. To address this issue, we designed and synthesized hollow CoP/FeP4heterostructural nanorods interwoven by carbon nanotubes (CoP/FeP4@CNT) via a hydrothermal reaction and a phosphorization process. The CoP/FeP4@CNT hybrid catalyst delivers prominent OER electrochemical performances: it displays a substantially smaller Tafel slope of 48.0 mV dec−1and a lower overpotential of 301 mV at 10 mA cm−2, compared with an RuO2commercial catalyst; it also shows good stability over 20 h. The outstanding OER property is mainly attributed to the synergistic coupling between its unique CNT-interwoven hollow nanorod structure and the CoP/FeP4heterojunction, which can not only guarantee high conductivity and rich active sites, but also greatly facilitate the electron transfer, ion diffusion, and O2gas release and significantly enhance its electrocatalytic activity. This work offers a facile method to develop transition metal-based phosphide heterostructure electrocatalysts with a unique hierarchical nanostructure for high performance water oxidation.Keywords:CoP-FeP4heterojunction;hollow nanorods;oxygen evolution reaction
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
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IF 4.939
Ting Feng,Fang Wang,Yanjie Xu,Meijia Chang,Xiujuan Jin,Yulin zhou,Jinhua Piao,Jianfei Lei
Transition metal phosphides (TMPs) have attracted considerable attention as an advanced electrocatalyst for hydrogen evolution reaction (HER). Nevertheless, the catalytic efficiency of single-component TMPs is still restricted that cannot endure long-term running and easy to be corroded especially under harsh conditions. In this work, a multicomponent electrocatalyst combined with CoP/Ni 2 P heteronanoparticles and Co/Ni single-atom active sites (denoted as N–C@CoP/Ni 2 P) is rational designed and prepared. The obtained N–C@CoP/Ni 2 P electrode material exhibits enhanced performance with the overpotential of 153 mV at 10 mA cm −2 , and the small Tafel value of 53.01 mV dec −1 in 0.5 M H 2 SO 4 , and a satisfied result is obtained in basic media as well. The outstanding HER performance is mainly benefiting from the synergistic effect between CoP and Ni 2 P, and the highly catalytic faction of atomic Co/Ni dual sites. Furthermore, a powerful conductive network fabricated by N-doped carbon skeleton and in-situ grown CNTs improves the conductivity of catalyst. Such a stereoscopic 3D nanostructure is also facile to accelerate the shuttle of electrons and ions.
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NANOTECHNOLOGY
·
2020
·Vol. 31
·期 12
·125402
·
IF 3.551
Tianyun Chen,Rongrong Zhang,Bo Ye,Qinghua Yang,Huajian Xu,Lei Zheng,Longgang Wang
In this work, a cerium doped CoP nanoparticles (NPs) embedded in carbon nanotubes (CNTs) for efficient and durable hydrogen evolution was developed. The detailed preparation process was described as the followings. First, cerium was introduced into ZIF-67 to form Ce-doped ZIF-67 by a joint nucleation method. Then, the Ce-doped Co-CNTs was synthesized by carbonization of Ce-doped ZIF-67. During the process, the Co2+ was reduced to form Co NPs and the elegant nanostructure of CNTs was formed by the catalytic effect of Co NPs. Finally, by using Ce-doped Co-CNTs as the precursor, the target catalyst (Ce0.05-doped CoP CNTs) was obtained through a chemical vapour deposition (CVD) process in the presence of NaH2PO2. Results of the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the target catalyst maintained the original rhombic dodecahedron morphology of ZIF-67 and the CoP NPs were embedded in CNTs and distributed uniformly throughout the catalyst. In electrochemical measurements, the catalyst showed the best performance for HER in 0.5 M H2SO4 solution. The onset potential, Tafel slope, electron transfer resistance (Rct) and double-layer capacitance (Cdl) of the target catalyst was 49 mV, 78 mV dec−1, 19.2 Ω and 10.5 mF cm−2, respectively. Meanwhile, the catalyst yielded a current density of 10 mA cm−2 merely at an overpotential of 146 mV. Furthermore, it maintained 90% of the original current density in a chronoamperometry measurement and showed no obvious decay even after 2000 cycles scans in a long-term durability test.
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高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2021
·Vol. 168
·期 9
·094501
·
IF 4.316
Wei Huang,Jing Tang,Fangyuan Diao,Shuo Li,Hongyu Sun,Xinxin Xiao
Transition metal phosphides are promising oxygen evolution reaction (OER) catalysts due to their earth-abundant and cost-effective features. Here, nanostructured CoP nanoparticles locked in hollow nitrogen doped carbon frameworks (CoP@HNC) were successfully designed and characterized for their morphology, composition, and electrochemistry. In a typical low-temperature phosphorization process, the Co species in carbonized poly-dopamine (PDA) coated ZIF-67 are converted to either hollow CoP or small-sized solid CoP nanoparticles governed by the nanoscale Kirkendall effect. The PDA layers derived nitrogen-doped carbon components feature a hollow polyhedral structure, with CoP nanoparticles imbedded in the shell. CoP@HNC demonstrates a low overpotential of 327 mV for 10 mA cm−2 and a good operational stability (72 h) for alkaline OER. The HNC encapsulation affords the low electronic resistance between CoP nanoparticles, as well as the mechanical and chemical stability of composites by preventing the aggregation of CoP nanoparticles during the OER process.
研究领域:
材料科学
·
电化学
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2026
·
IF 6.3
Li Sun,Qing Guo,Fan Yang,Kexin Wei,Siyuan Sun,Hongchen Liu,Junpu An,Yang Sun,Yang Guo,Linjie Wang,Yongfeng Li
Rationally designing single-atom catalysts (SACs) with high atomic efficiency and excellent catalytic performance is effective for boosting sodium borohydride (NaBH 4 ) hydrolysis activity. Herein, a series of Pt single-atom catalysts supported on Co-based compounds (Pt/CoP-B, Pt/CoP, Pt/Co 3 O 4 -B) were successfully synthesized via wet impregnation method. Pt M /CoP-B (6.2 wt% Pt loading) exhibited optimal performance at 30 °C: a turnover frequency (TOF) of 1103.26 mol H2 min −1 mol −1 Pt , a hydrogen generation rate (HGR) of 10746 mL min −1 g −1 cat which corresponded to 1.46 times higher than Pt M /Co 3 O 4 -B and 1.33 times higher than Pt M /CoP, outperforming most reported noble metal-based catalysts. It also possessed a low activation energy of 31.05 kJ mol −1 and excellent cycling stability, retaining 95.15 % of initial activity after five consecutive cycles. XPS confirmed strong metal-support interaction between Pt single atoms and CoP-B, which inducing electron transfer from Pt to Co to form electron-deficient Pt and electron-rich Co. DFT calculations revealed that Pt/CoP-B imposes a much lower energy barrier for rate-determining B–H bond cleavage and more effectively promotes H 2 O adsorption. This work offers a new paradigm for creating complementary electronic sites via single-atom-support synergy, opening a novel avenue for advanced NaBH 4 hydrolysis catalysts.
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