Application Of Perovskite Oxides In Oxygen Evolution Reaction Of Alkaline Electrolytic Water Splitting

The rational design of oxygen evolution reaction（OER）catalyst with low cost,high activity and good stability is of vital importance for the implementation of electrochemical water oxidation as a sustainable route to produce hydrogen.Perovskite oxide is a kind of metal oxide with low price,sufficient reserves and various structures.As a non noble metal catalyst,perovskite oxide has attracted extensive attention in the field of oxygen evolution reaction in alkaline medium.Single phase perovskite oxide OER catalysts generally have poor phase stability and low conductivity.The above shortcomings can be improved by mechanical compounding of different phases or preparing composite phases by impregnating different phases.However,these preparation methods are too cumbersome and the uniformity of material particles is poor.This thesis aims to design and optimize the perovskite structure through simple element doping and external solution precipitation alloy technology,so as to realize the efficient application of perovskite oxides in the catalytic reaction of electrolytic water oxygen precipitation.In this thesis,two new OER catalyst materials:SrCo_0.7Sn_0.3O₃（SCS）and Sr_1.9FeMo_0.55Co_0.45O₅-Co Fealloy have been developed to solve the above problems.The crystal structure,conductivity,specific surface area,electrochemical properties and stability were studied.The research results of this thesis are as follows:Sn doped SrCoO₃（SC）was prepared by high temperature solid state reaction material:SrCo_0.7Sn_0.3O_3-δ（SCS）.Due to the doped of Sn,SC changes from 2H-Ba Ni O₃marmatite structure to stable cubic perovskite structure.The average valence state of B-site ions of SCS at room temperature is higher than that of SC material,and the conductivity is also higher than that of SC.At an overpotential of 340 m V,the mass activity and specific activity of SCS were about 72 and 108 times higher than that of raw material SC,respectively.Under the current density of 5 m A cm^-2,the over potential of the new composite can be basically stable within 30 hours of operation.This high electrochemical stability is due to the doping of Sn in SCS composites,which can maintain the stability of SC cubic symmetrical structure.Excellent OER activity and stability make SCS composites have great application potential.Sr_1.9FeMo_0.55Co_0.45O₅-Co Fealloy composite was prepared by sol gel method and reduction atmosphere treatment.After treating in 8%H₂reducing atmospherethe,the specific surface area and oxygen vacancy of parent material were increased,which makes the material obtain more OER active sites,so that the material has faster OER reaction kinetics.Sr_1.9FeMo_0.55Co_0.45O₅-Co Fealloy composite show a low overpotential（334 m V）at a current density of 10 m A cm^-2.The MA and SA at 330 m V overpotential are 11.2 and 9.9times higher than those of raw materials.