The Construction And Properties Of Transition Metal Compound As Electrocatalysts

With the development of the times,human society is constantly moving toward a more civilized direction.Unfortunately,the world's energy consumption is rising year by year,so it is urgent to develop green and sustainable clean energy.Hydrogen?H₂?is considered to be the most promising green energy alternative to fossil fuels due to its high efficiency and cleanliness.At present,electrocatalytic water splitting is recognized as an important method for large-scale preparation of hydrogen,which includes a hydrogen evolution reaction and an oxygen evolution reaction.However,a major factor limiting the development of electrocatalytic electrocatalytic water splitting technology is the consumption of precious metal catalysts for both cathode and anode to promote the reaction.Therefore,the development of cheap and high-performance non-noble metal catalysts for hydrogen or oxygen evolution is very challenging.Some transition metal?Mo,Fe,Ni?based materials are promising substitute for Pt and RuO₂-based catalysts due to their low cost and remarkably electrocatalytic performance.Here,the content of our research work is discussed by three parts.First,the three-dimensional graphene/transition metal?FeMo?compound is prepared by one-step hydrothermal method,then nitrogen doped Fe/Mo-NC-1000 composite is obtained by high temperature pyrolysis.The effect of pyrolysis temperature on electrocatalytic performance is discussed.The catalyst shows excellent HER performance in both acid and base media;Secondly,Ni-MOFs is synthesized by simple solvothermal method,following MOF-polymer core-shell material containing functional compound is synthesized by water bath heating and then phosphated to obtain NiFe-MoPC-NC-1000 with high specific surface area,porous structure,high active site and faster electron transport rate,and its electrocatalytic performance for HER and OER is observed;Thirdly,a hierarchical morphology and high-defect NiFe layered double hydroxide?NiFe-LDHs?is constructed on nickel foam?NF?by one-step electrodeposition?ED?strategy.The effects of the introduction of anionic species and a third metal element on the morphology,composition and electronic structure of LDHs are investigated.The catalytic performance of NiFe LDHs for OER and HER in alkaline conditions is investigated.All as-prepared catalysts are characterized by various characterization techniques.For example,SEM,TEM and XRD are used to characterize the morphology and composition of the material;XPS is used to qualitatively analyze the material;Nitrogen adsorption/desorption test is used to test the specific surface area and pore structure of the material and the graphitization degree of the material is analyzed by Raman spectroscopy;And the electrochemical catalytic properties of the material were evaluated by a series of electrochemical tests.For example,the electrochemical performance of the prepared catalyst is evaluated using CV,LSV and EIS.It was found that the optimal Fe/Mo-NC-1000,NiFe-MoPC-NC-1000 and Fe²⁺-NiFe LDHs CO₃^2-/NF catalysts show excellent HER catalytic activity and stability,but NiFe-MoPC-NC-1000 and Fe²⁺-NiFe LDHs CO₃^2-/NF exhibit excellent OER and HER catalytic properties in alkaline condition.In particular,the overall electrochemical water splitting performance of Fe²⁺-NiFe LDHs CO₃^2-/NF material is superior to the best commercial catalysts combination of Pt/C and RuO2.