Studies On Preparation And Performance Of Several Transition Metal Base Electrocatalytic Materials

The rapid development of industry and economy in our society brings unprecedented challenges to energy consumption and environmental protection.Seeking clean energy that can replace fossil fuels to solve the energy crisis and environmental problems has become a national issue.Therefore,research and development of an environment-friendly and sustainable development of clean energy technology in accordance with today’s society has attracted widespread attention.Electrocatalytic water splitting is an ideal method for preparing clean energy.In this technology,the hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）are a half reaction of electrocatalytic water splitting.The high overpotential and slow kinetics limit their application,so it is necessary to develop catalysts with efficient catalytic performance to promote the rapid progress of water splitting.At present,noble metals（such as Pt,Ir,Ru etc.）are considered as good catalysts for HER and OER.However,the high cost and lack of storage of noble metals have greatly limited their wide application in the catalysis field,so that designed and synthesized efficient and cheap non-noble metal materials become an urgent and valuable research.Transition metals（specifically refers to Ni,Fe,Co,Mo and other non-noble metals,the same as below）are not only cheap but also abundant in storage.At the same time,the unique electronic structure of these metals gives them unique properties and is widely used in the research of high-performance materials in the field of electrocatalysis.At present,many transition metal materials suffer from many problems such as poor conductivity and few active sites for reactions,which limits their applications in electrocatalysis.Based on these considerations,we use a simple method to rationally design several transition metal-based materials for HER,and conducts a series of studies on the structure and performance of these catalytic materials.The main research contents of these are as follows:（1）Metal-organic framework-derived nitrogen-doped carbon-RhNi alloy anchored on graphene for highly efficient hydrogen evolution reactionAlloying highly active noble metals with transition metals as an excellent HER catalyst is an effective strategy.It can not only effectively reduce the amount of noble metals,but also greatly improve the performance of the catalyst.In this work,bimetallic RhNi-MOFs were anchored on graphene as a precursor,and nitrogen-doped carbon-RhNi alloy nanoparticles obtained by pyrolyzing the precursor,denoted as NC-RhNi/rGO.The NC-RhNi/rGO catalyst has a small overpotentials of37 and 34 mV at a current density of 10 mA cm^-22 in 1.0 M KOH and 0.5 M H₂SO₄,respectively.The catalyst has great HER performance,even better than commercial Pt/C.The study results show that the excellent activity benefits from the synergistic effect of the bimetal alloy and the unique structure,which can effectively promote electron transfer,and the unique structure provides rich active sites.This work provides a promising method for the synthesis of nano-composite electrocatalysts for efficient HER.（2）Phosphating cobalt array directly grown on the surface of cobalt film as a self-supporting electrode for efficient hydrogen evolution reactionAt present,powdery catalysts require additional binders during the test process,which not only reduces the active sites of the catalyst,but also the catalyst will fall off due to large number of bubbles generation during the test process,making the catalyst loss catalytic performance.Therefore,in this chart,a self-supporting integrated electrode with a unique array microstructure was successfully prepared by a simple two-step method.This unique structure allows it to have more active sites and a high electron transport rate,making the catalytic shows a great HER performance in 1 M KOH.Experimental results show that at a current density of 10 mV cm^-2 it only requires an overpotential of 110 mV,has a low Tafel slope of 76 mV dec^-1,and maintains good stability after testing the electrolyte for 20 h.This work provides a feasible methodological guide for designing and synthesizing special structures of self-supporting array with excellent catalytic performance.