近年来，能源消耗的日益增长和环境污染问题的日益严重引起了公众的广泛关注

In recent years, the increasing energy consumption and the increasingly serious environmental pollution problems have caused widespread public concern. Traditional fossil energy is widely used because of its convenient use and low cost of acquisition, but the corresponding negative impacts gradually cannot be ignored. Exploring alternative energy and sustainable energy conversion, and establishing corresponding energy storage systems to cope with the current energy crisis have become an urgent problem to be solved. Hydrogen energy stands out from many new energy sources because of its high energy density and environmentally friendly products. It is considered by researchers as the most promising renewable energy source to replace traditional fossil energy sources. Currently, electrolysis of water to produce hydrogen is the most economical and sustainable method for large-scale hydrogen production. However, due to the slow reaction kinetics and high overpotential, the currently developed electrolytic water hydrogen production technology is difficult to achieve large-scale practical applications. In view of this situation, it is necessary to use high-efficiency precious metal catalysts (such as Pt, Rh, RuO2, etc.) to reduce the excessive potential of electrocatalytic reactions and improve the reaction kinetics. However, their high cost and low abundance have greatly hindered large-scale practical applications. Therefore, it is an important and urgent task to develop low-cost, abundant reserves, and efficient non-precious metal catalysts to replace precious metal catalysts such as platinum and rhodium. <br>This paper focuses on the design and preparation of an efficient self-supporting cobalt phosphide / molybdenum heterostructure catalyst. Using carbon cloth as a self-supporting conductive substrate, non-noble metals are grown on the carbon cloth in situ by gas-phase hydrothermal method. After simple roasting with sodium hypophosphite in argon, the structure characteristics are clear, the composition is accurate, and the heterostructure is obtained. The non-precious metal catalyst exhibits excellent electrolysis water catalytic hydrogen evolution and oxygen evolution performance. The specific research contents are as follows: <br>1. Using carbon cloth as a self-supporting substrate, urea and ammonium fluoride as etchant, and cobalt nitrate hexahydrate as raw materials, the precursor of cobalt fluoride hydroxide was synthesized by gas-phase hydrothermal method. The precursor and sodium hypophosphite were fired in an argon atmosphere to synthesize CoP / CC nanowire material. The product self-supporting MoO2 / CoP / CC heterostructure catalyst is prepared by cobalt phosphide and sodium molybdate dihydrate by gas phase hydrothermal method.<br>2. Characterized by XRD, SEM, TEM and other instruments, the results show that the MoO2 / CoP / CC nanowires maintain the original CoP / CC nanowire needle-like morphology, the surface is rougher, the grains become smaller, and the molybdenum oxide is evenly wrapped On the surface of cobalt phosphide nanowires. There is a distinct heterojunction interface between cobalt phosphide and molybdenum oxide. This interface can increase the specific surface area of ​​the electrochemical activity of the catalyst and provide more exposed active sites. The synergistic effect of molybdenum oxide and cobalt phosphide in the heterostructure is also beneficial to improve the electrocatalytic activity. <br>3. The electrochemical performance test shows that with 1 M KOH alkaline solution as the medium, the overpotentials required for the CoP / CC and MoO2 / CoP / CC catalyst materials to reach a current density of 10 mA cm-2 in the hydrogen evolution reaction are respectively 137 mV and 120 mV; 350 mV and 210 mV in the oxygen evolution reaction, respectively. At the same time, the results of electrochemical AC impedance and ECSA indicate that MoO2 / CoP / CC has lower impedance and larger specific surface area of ​​electrochemical activity than CoP / CC. <br>4. Design experimental plans for preparing multiple sets of comparative experiments by controlling the Mo / Co ratio, observe the influence of the Mo / Co ratio on the formation of heterostructure interfaces through XRD, SEM, TEM and other morphological characterization, and find the most through electrochemical performance testing Mo / Co ratio with good catalytic performance. Provide a promising electrocatalyst for practical applications.

In recent years, the increasing energy consumption and environmental pollution problems have aroused widepublic concern. Traditional fossil energy is widely used because of its easy use and low access cost, but the corresponding negative effects can not be ignored. Exploring alternative and sustainable energy conversion, as well as establishing corresponding energy storage systems to address the current energy crisis, has become an urgent problem to be addressed. Hydrogen energy, because of its high energy density and environmentally friendly use products, stands out from many new sources of energy and is considered by researchers to be the most promising alternative to traditional fossil fuels. At present, electrolytic water decomposition hydrogen production is the most economical and sustainable method of large-scale hydrogen production. However, due to the slow reaction dynamics and high super-electric potential, the current development of electrolytic aquatic hydrogen technology is difficult to achieve large-scale practical application. In view of this situation, efficient precious metal catalysts (e.g. Pt, Rh, RuO2, etc.) are required to reduce the high potential of the electrocatalytic reaction and improve reaction dynamics. However, their high cost and low abundance greatly hinder large-scale practical applications. Therefore, the development of low-cost, abundant and efficient non-precious metal catalysts to replace platinum, palladium and other precious metal catalysts is an important and urgent work.<br>This paper is based on the design and preparation of an efficient self-supporting phosphated cobalt/radon heterostructure catalyst. Using carbon cloth as a self-supporting conductive substrate, non-precious metals are grown in situ by gas-phase hydrothermal method, and after simple roasting with sodium hypophosphate in argon, the non-precious metal catalyst with clear structure characteristics, precise composition and heterogeneous structure shows excellent electrolytic hydrolysis hydrogen and oxygen analysis. The specific research content is as follows:<br>1. Using carbon cloth as a self-supporting substrate, urea, ammonium fluoride as an etching agent, cobalt nitrate in hexagon as raw material, through gas-phase hydrothermal method synthesis of cobalt fluoride pre-exorcised. The precursor and sodium hypophosphate are roasted in argon atmosphere and the CoP/CC nanowire material is synthesized. The phosphated cobalt and sodium dihydrated argon were self-supported by the gas-phase hydrothermal legal system to support the MoO2/CoP/CC heterogeneous structure catalyst.<br>2. Through the representation of XRD, SEM, TEM and other instruments, the results show that MoO2/CoP/CC nanowires are more rough on the surface, grain smaller, and zirconia is evenly wrapped on the surface of the phospanded cobalt nanowire on the basis of maintaining the original CoP/CC nano-wire needle-like appearance. There is a clear heterogeneous junction interface between phosphated cobalt and molybdenum oxide, which can increase the electrochemical activity ratio of the catalyst to the surface area and provide more exposed activity sites. The synergy between radon oxide and phosphated cobalt in heterogeneous structure is also beneficial to improve electrocatalytic activity.<br>3. Electrochemical performance testshows show that with 1 M KOH alkaline solution as the medium, the excess potential required for CoP/CC, MoO2/CoP/CoP/CC catalyst material to reach 10 mA cm-2 current density in hydrogen analysis reaction, and 350 mV and 210 mV respectively in the oxygen analysis reaction. At the same time, electrochemical AC impedance and ECSA results show that MoO2/CoP/CC has smaller impedance and larger electrochemical activity ratio of surface area than CoP/CC.<br>4. By controlling the experimental scheme of Mo/Co scale preparation for multiple sets of comparative experiments, the influence of Mo/Co scale on the formation of heterogeneous structure interface is observed by XRD, SEM, TEM and other morphological representation, and the Mo/Co ratio in the case of optimal catalytic performance is found by electrochemical performance test. Provides a promising electrocatalyst for practical applications.

In recent years, the increasing consumption of energy and the increasingly serious problem of environmental pollution have aroused widespread public concern. Traditional fossil energy is widely used because of its convenient use and low cost, but the corresponding negative impact can not be ignored. It has become an urgent problem to explore alternative energy and sustainable energy conversion, and establish corresponding energy storage system to deal with the current energy crisis. Because of its high energy density and environmentally friendly products, hydrogen energy stands out from many new energy sources and is considered by researchers to be the most promising renewable energy alternative to traditional fossil energy. At present, electrolytic water decomposition is the most economical and sustainable method for large-scale hydrogen production. However, due to the slow reaction kinetics and high overpotential, it is difficult to realize the large-scale practical application of the currently developed electrolytic hydrogen production technology. In view of this situation, it is necessary to use highly efficient noble metal catalysts (such as Pt, Rh, RuO2, etc.) to reduce the over potential of electrocatalytic reaction and improve the reaction kinetics. However, their high cost and low abundance greatly hinder the large-scale practical application. Therefore, it is an important and urgent work to develop low-cost, abundant and efficient non noble metal catalysts to replace platinum, rhodium and other noble metal catalysts.<br>In this paper, the design and preparation of an efficient self-supporting cobalt / molybdenum phosphide heterostructure catalyst is the main research content. Using carbon cloth as self-supporting conductive substrate, the non precious metals were grown on the carbon cloth in situ by gas-phase hydrothermal method. After simple calcination with sodium hypophosphite in argon, the non precious metal catalysts with clear structure characteristics, accurate composition and heterogeneous structure were obtained, showing excellent catalytic hydrogen and oxygen evolution performance of electrolytic water. The specific research contents are as follows:<br>1. Using carbon cloth as self-supporting substrate, urea and ammonium fluoride as etchant, cobalt nitrate hexahydrate as raw material, the precursor of cobalt hydroxide fluoride was synthesized by gas-phase hydrothermal method. The precursor and sodium hypophosphite were calcined in argon atmosphere to synthesize cop / cc nanowires. The product self supported MoO2 / cop / cc heterostructure catalyst was prepared by gas-phase hydrothermal method with cobalt phosphide and sodium molybdate dihydrate.<br>2. The results of XRD, SEM and TEM show that MoO2 / cop / cc nanowires keep the needle like morphology of the original cop / cc nanowires, the surface is rougher, the grains are smaller, and molybdenum oxide is evenly wrapped on the surface of cobalt phosphide nanowires. There is an obvious heterojunction interface between cobalt phosphide and molybdenum oxide, which can increase the specific surface area of the catalyst and provide more exposed active sites. The synergistic effect of molybdenum oxide and cobalt phosphide in the heterostructure is also conducive to improving the electrocatalytic activity.<br>3. The electrochemical performance test shows that the overpotential of cop / cc and MoO2 / cop / cc catalysts is 137 MV and 120 MV respectively when they reach 10 Ma cm-2 current density in hydrogen evolution reaction, and 350 MV and 210 MV respectively in oxygen evolution reaction. The results of electrochemical impedance and ECSA show that MoO2 / cop / CC has smaller impedance and larger specific surface area than cop / cc.<br>4. Design the experimental scheme of preparing multiple groups of comparative experiments by controlling the Mo / CO ratio, and observe the influence of Mo / CO ratio on the formation of heterogeneous structure interface by XRD, SEM, TEM and other morphological characterization. Find the Mo / CO ratio under the best catalytic performance by electrochemical performance test. It provides a promising electrocatalyst for practical application.<br>