| The rapid economic development,increasing energy demand,and rapid consumption of fossil energy have brought a series of problems such as environmental pollution and the greenhouse effect,which have also caused global reserves to decline rapidly.If we cannot find other alternative energy sources,we will eventually face the crisis of energy exhaustion and environmental pollution.Scientists are committed to developing technologies that can use clean and renewable energy sources such as solar energy,wind energy and hydropower,but these energy sources are discontinuous and unstable due to environmental impacts.Using intermittent wind or solar energy to convert it into electricity,using electrolyzed water to produce hydrogen and oxygen,and storing excess electricity in the form of hydrogen is the cleanest energy use.However,currently,the hydrogen evolution reaction（HER）requires Pt,and the scarcity of resources and high cost hinder the further development of the technology.Therefore,the development of resource-rich and easily available transition metal sulfur-phosphides to replace precious metal catalysts will enable the conversion and storage of clean and sustainable energy.The valence electron structure and highly exposed active crystal plane is the key to develop efficient,low-cost and durable electrocatalysts for the effectual HER.The molecular precursor P2S5 sulfur-phosphidating alkali-etched hexagonal sheet Co Al-LDH/MWCNTs introduces P into the Co S2 lattice at high temperature to obtain a porous sheet Co P0.8S1.2/MWCNTs（CPS/C）.The sulfur-phosphidating temperature is used to control the doping amount of P to improve the electronic structure and properties of the catalyst.The obtained CPS/C catalyst is used for the hydrogen HER and has high activity over a wide p H range.In 0.5 M H2SO4,CPS/C has an overpotential of only 49 m V at 10 m A·cm–2 and a small Tafel slope(39 m V·dec–1).The catalytic performance of CPS/C is closed to 20 wt%Pt/C.According to Density Functional Theory（DFT）calculation,after replacing some S atoms with P atoms,the Gibbs free energy of the free hydrogen adsorbed during the reaction can be reduced,thus greatly improving the catalytic activity of HER.This study will modify the chemical and electronic structures of the material by uniformly doping P atoms into Co S2,providing an effective strategy for improving the activity of catalysts.At present,a large number of electrocatalysts have been developed,but non-precious metal electrocatalysts that are efficient and stable under large currents are difficult to obtain.By introducing transition metal Cu,the structure of Co-based non-noble metal catalysts was adjusted to obtain high-performance HER catalysts.A nano flower composed of hydrothermally synthesized Co Cu double hydroxide nanosheets was used as a precursor,and P2S5 was used as a sulfur-phosphidating agent at high temperature to obtain a non-precious metal HER catalyst with high activity of Co Cu sulfur-phosphides（MPS）.The introduction of Cu interacts with the original Co element to form a uniform structure,and the thickness of the precursor nanosheets can be controlled by changing the Cu content to obtain a structurally stable material.The interaction of Co and Cu can also adjust the electronic structure of the catalyst to improve the catalytic activity,which is superior to Pt/C performance under large current.The method of transition metal adjusting the structure and properties of the catalyst can be widely applied to the modification of other catalysts.In summary,a series of transition metal sulfur-phosphide materials were obtained from sheet metal hydroxide as a self-sacrifice template and high temperature sulfur-phosphidating reaction of P2S5 molecular precursor.Its sheet-like structure can provide a large active surface and fast mass transfer rate,and shows excellent performance in HER.Considering the rich composition and structure of metal hydroxides,as well as the advantages of controllable synthesis,various types and structures of metal sulfur-phosphides can be obtained.The method proposed in this paper can be extended to the preparation of other metal-based sulfur-phosphide materials,and has multifunctional properties in renewable energy storage and conversion applications. |
