Research On The Controlled Synthesis And Electrolytic Properties Of Transition Metal Nitride Nanomaterials

Hydrogen production by electrolytic water is regarded as one of the important technologies to alleviate energy problems and develop clean and sustainable energy in the future because of its wide source of raw materials,green pollution,high purity of products and flexible production.Precious metal catalysts（such as platinum,ruthenium,iridium,etc.）show the best catalytic performance in the water electrolysis process,but their high cost and scarce resources limit the widespread promotion of hydrogen production technology.Therefore,finding cheap,efficient,durable and green catalysts has become the key to breakthrough hydrogen production technology.The Pt-like band structure of Transition metal nitrides（TMNs）enables them to exhibit platinum-like catalytic activity in theory,so they are widely concerned and regarded as ideal catalysts for electrolytic water.However,as a traditional metal catalyst,its electrocatalytic activity is far from the industrial catalytic level.In order to break through the restriction problem,it can be improved from the following three aspects:It can be improved from the following three aspects:（1）using conductive substrate（carbon matrix,nickel foam,etc.）to extend its service life,enhance electrical conductivity and prevent the aggregation of active molecules,while avoiding the use of binders;（2）Construct the interfacial heterogeneous structure and make full use of its synergistic effect to optimize the electronic structure of the material;（3）The eigen activity of the electrocatalyst was increased by element doping modification,while the△G_H*of the catalytic material was decreased.In this paper,hydrothermal method,gas phase nitriding method and gas phase phosphating method are mainly used to synthesize carbon coated with Co PN@CNB and V-Co Mo Nx,Cr,P-Co₃Mo₃N catalyst materials supported on nickel foam substrate,and applied to catalyze hydrogen evolution,oxygen evolution and total water hydrolysis reactions.Specific studies are as follows:1.In the second chapter of the experimental system,the influence of the introduction of carbon shell and N element on the composition and morphology of cobalt-based phosphide materials is mainly explored,and the influence of the change of microstructure on the optimization of electrocatalytic performance is analyzed.The construction of porous carbon matrix and the introduction of non-metallic elements are the main reasons for the improvement of its catalytic performance.Porous carbon structure can prevent the aggregation and oxidation of active sites,enhance its electrical conductivity,accelerate the electron transport and chemical reactivity in the catalytic process,and provide more active area.The introduction of N element can further optimize the electronic structure and improve the efficiency of electrocatalytic hydrogen evolution.2.In the third chapter of the experimental system,the effects of metal doping and heterogeneous structure on the composition,morphology and electrocatalytic performance of cobalt-molybdenum bimetallic nitriding materials are mainly explored.When the nitriding temperature was 500°C,the nanocolumn clusters supported by nickel foam substrate were obtained.The electrochemical test results showed that the nanocolumn clusters exhibited low overpotential and excellent stability in the performance of hydrogen evolution,oxygen evolution and complete water hydrolysis.The experimental results show that V metal doping can change the morphology of cobalt-molybdenum bimetallic nitrides,forming a unique cluster of nano-column structure.Metal doping can optimize its electronic structure and provide more active sites.The introduction of nickel foam substrate plays a role of dispersing active components,enhancing electrical conductivity and further optimizing catalytic activity.3.In the fourth chapter of the experimental system,the effects of the co-doping of metal elements and non-metal elements on the composition,morphology and electrocatalytic performance of cobalt-molybdenum bimetallic nitriding materials are mainly studied.With 0.5239 g of cobalt nitrate and 80 mg of sodium phosphomolybdate(n _Co:n _Mo=1:2),six-sided nanocrystals with uniform size were formed and supported on nickel foam substrate,which showed high stability and electrocatalytic activity.The experimental results show that the co-doping of metallic elements with non-metallic elements can improve the intrinsic activity of catalyst,and the introduction of heteroatoms can optimize the electronic structure of nitrides and adjust the active sites.The three-dimensional network structure of nickel foam can increase the exposure of its active sites,enhance the conductivity of the catalytic material,and thus improve the electrocatalytic performance.