| Electrocatalysis of H2evolution reaction（HER）is a clean sustainability and promising strategy to extract H2.However,the activation energy barrier of H-O bond of water molecule is high and the rate of HER is slow.The key to realize large-scale hydrogen production by HER is to develop efficient catalysts with the reaction potential and reduce energy loss.Pt noble metals as one of the most advanced HER catalysts have smaller overpotential and Tafel slope.But their scarce properties largely limit their further applications.It is urgent to find catalysts with high performance and rich reserves.Molybdenum disulfide is a potential ideal catalyst,which has the advantages of low price and good stability.However,molybdenum disulfide only has active sites exposed at the edge and small layer spacing,which results in low catalysis HER activity.To improve the electrocatalysis performance,the over potential of the catalyst can be reduced by compounding with heteroatomic sulfides or selenides of other transition metals such as Co,Ni and so on,and adjusting the supported substrate of the catalyst.These methods can significantly optimize the morphology and increase the number of effective active sites of catalysts.Polyoxometalate can be conveniently optimized by regulating its components and thus it is an ideal pre-assembly platform for heterometallic electrocatalysts.Therefore,in this paper,two kinds of polymer-based complexes with new structures were designed and constructed.By employing the two complexes as precursors,novel Cu2S-Mo S2and Co S2-Mo S2-VS2heterometallic catalysts were prepared by"one pot"hydrothermal vulcanization method.These heterometallic catalysts were directly coupled in situ on the surface of carbon cloth.On the other hand,cobalt molybdate was selected as the precursor,and Cu2S-Mo S2heterometallic catalyst was directly coupling on carbon cloth in situ by a one-step hydrothermal vulcanization.Subsequently,using cobalt molybdate polymers as bimetallic source and nickel foam as metal source,combined with the synergistic advantage of selenium and sulfide heterostructures,a novel multi-component composite electrode Mo S2/Co S2@Ni3S2/Ni3Se2was prepared by hydrothermal vulcanization and selenization procedures.All of the composites prepared in this paper can be directly used as working electrodes and show excellent catalytic hydrogen evolution performance.The specific work is listed as follows:1.Using Keggin phosphomolybdate acid,metal salts copper nitrate and cobalt nitrate as well as organic ligand 2,2’-bipy as raw materials,two new crystalline polyacid coordination polymers:[H42{Cu I（bipy）}6(Mo 6VO22)](H4PMo 6VO20)2·H2O（1）[Co II（bipy）7（H2O）4]2[HPMo V6Mo VI6O40(VIVO)2]·4H2O（2）were synthesized by a simple"one pot"hydrothermal synthesis method.Using the above coordination polymers as precursors,two metal sulfides Cu2S-Mo S2-CC and Co S2-Mo S2-VS2-CC were prepared by a one-step hydrothermal vulcanization route.In 1.0 M KOH electrolyte,when the current density is 10 m A cm-2,the Cu2S-Mo S2-CC and Co S2-Mo S2-VS2-CC show small overpotential（159 m V and 152 m V）and low Tafel slope(109 m V dec-1and 107m V dec-1).2.Using（C3H5N2）6[Co IIMo12O40]·10H2O(Co Mo12)as metal source,thiourea as sulfur source and carbon cloth as substrate,a new composite Co S2-Mo S2-CC was prepared by one pot hydrothermal synthesis.Using Co Mo12as metal source,thioacetamide（TAA）as sulfur source,nickel foam（NF）as nickel source and substrate,a composite Mo S2/Co S2@Ni3S2/Ni3Se2was fabricated by hydrothermal vulcanization and selenization stepwise assembly procedures.In1.0 M KOH electrolyte,when the current density is 10 m A cm-2,the overpotential of the catalytically resolved water reaction for Co S2-Mo S2-CC and Mo S2/Co S2@Ni3S2/Ni3Se2ware 69 m V and 56 m V respectively,which are close to that of the overpotential of Pt electrode（35 m V）.Meanwhile,the tests of XRD before and after catalytic reaction and 24-hour stability show that the two electrodes have excellent stability in the electrolyte of 1.0 M KOH. |
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