Study On Preparation And Catalytic Performance Of MOFs And Their Derivatives Electrolytic Water Catalysts

The process of hydrogen production obtained by electrolytic water has some advantages（e.g.,easy availability of raw materials,green pollution and so on）,which has triggered wide attentions.At present,the catalyst of the precious metal（Pt）based material has the best performance of hydrogen evolution reaction（HER）,but its disadvantages including high price and low abundance limit its large-scale applications.Therefore,it is necessary to develop and prepare economical,efficient and stable electrocatalysts for HER reactions.Metal-organic framework（MOFs）are getting much more attention in the field of electrocatalysis due to their unique framework structures and uniform active metal nods.Meanwhile,a nickel foam substrate acted as an electrode is facilitated to the loading of active materials,which can enhance electron transports and hydrogen diffusions and improve hydrogen evolution activities.Accordingly,nickel foam was elaborately selected as a substrate,while MOFs were used as precursors.And,two kinds of catalyst materials containing transition metals were designed and synthesized in situ on nickel foam for electrolytic water hydrogen evolutions in this work.The electronic structures and material morphologies were regulated by controlling reactant ratios and calcination temperature to improve electrocatalytic performances of the materials.Main contents of the work are as follows:（1）Bimetallic composite MOFs（Ce-MOF@Co-MOF/NF）were prepared by using a hydrothermal method as Ce-MOF and Co-MOF were sequentially in-situ grew on the surface of a nickel foam.The composite was characterized by XRD,SEM and TEM technologies and was tested and evaluated for HER in alkaline electrolyte.The results indicated that the bimetallic material Ce-MOF@Co-MOF/NF is provided with optimum HER activity as the molar ratio of Ce/Co is 1:4.And,the required overpotential is 145.1m V as the current density is 10 m A cm^-2.In addition,Ce-MOF@Co-MOF/NF was further used as a precursor to construct Ce-Co/NF@P prepared through doping phosphorus.The evaluation results illustrated that the composite has the optimum HER activity as calcination temperature is 300℃.The material exhibited a good charge transfer impedance,specific surface area of electric activation.The overpotential is only 130.0 m V at 10 m A cm^-2,while Tafel slope is 103 m V dec^-1.（2）Using nickel foam as substrate,Mo Se₂@Ni-ZIF/NF composite material was synthesized by hydrothermal method in one step as the prepared Ni-ZIF/NF material was introduced into the synthesis process of Mo Se₂.The composite was characterized by XRD,SEM and TEM technologies.The preparation process of catalyst was optimized by investigating the effect of different dosage of precursor Ni-ZIF on hydrogen production performance.The results showed that the composite material is provided with optimum HER activity as the amount of Ni-ZIF was 1 m M.The material exhibited a good charge transfer impedance,specific surface area of electric activation.The measured overpotential is 86.3 m V,the Tafel slope is 76 m V dec^-1.