The Preparation,Characterization And Performance Study Of A New Type Of Perovskite Structure Water Splitting Catalyst

Due to the slow kinetics of the two half-reactions of electrolyzed water,water splitting cannot proceed spontaneously.The introduction of electrocatalysts is urgently needed to improve the reaction rate and hydrogen production efficiency.Perovskite materials have become a research hotspot in the field of electrocatalysis due to their rich element composition and structural diversity.However,its low electrical conductivity,low specific surface area,and poor electrochemical stability at room temperature limit its wide application in the field of electrocatalysis.Based on this,this dissertation is guided by improving the electrocatalytic performance of perovskite,taking the high conductivity of electrocatalysts,larger electrochemically active area,and more electrochemically active sites as the starting point.A series of optimization of the composition and morphology of the catalyst,theelement doping of A site and other high-efficiency electrocatalyst composite methods were used to achieve a perovskite material with high electrocatalytic activity,stability,and dispersibility.The specific contents are as follows:1.Study on Ce-doped La Co O₃perovskite as a bifunctional electrocatalyst for hydrogen and oxygen evolutionIn this chapter,a microwave/ultrasonic-assisted hydrothermal method was used to synthesize Ce-doped La Co O₃perovskite oxide as a bi-functional electrocatalyst for oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）applications,which achieved high-efficiency bidirectional electrocatalytic performance.The obtained La_0.6Ce_0.4Co O₃sample had good electrocatalytic activity.At 10 m A/cm²,the overpotential to OER and HER were 380 m V and 305 m V,respectively.The Tafel slopes of OER and HER were 80 m V/dec and 144m V/dec,respectively,indicating their fast reaction kinetics.The excellent long-term durability of La_0.6Ce_0.4Co O₃under alkaline conditions was also crucial to the practical application of water electrolysis.At the same time,the synergistic effect of the excellent electrical conductivity and enriched active sites produced by the substitution of the A site made the electrocatalytic activity of the La_0.6Ce_0.4Co O₃material further increased,becoming a potential OER and HER dual-function electrocatalyst.2.Study on Sn-doped LaNiO₃perovskite as an electrocatalyst for Oxygen EvolutionIn this chapter,a series of LaNiO₃with different Sn substitution ratios were prepared by hydrothermal method,and it had obvious electrocatalytic activity for OER.The composition and structure of perovskite oxide were systematically studied by powder X-ray diffraction and high-resolution transmission electron microscopy.The optimized La_0.9Sn_0.1Ni O_3-δcatalyst had good stability and significantly enhanced electrocatalytic activity in alkaline electrolytes.The overpotential was318 m V at 10 m A/cm²,which was lower than the original LaNiO₃（449m V）.Transient Photovoltaic Voltage（TPV）experiments confirmed that Sn-substituted interface charge transfer was faster.At the same time,density function theory（DFT）calculations showed that Sn substitution effectively enhanced the covalent relationship between Ni 3d-O 2p.Moreover,the interaction between the oxygen-containing substance adsorbed on the surface of the catalyst and the active site was enhanced,which helped the activation of surface water molecules,thereby further improving its OER electrocatalytic performance.3.Study on LaNiO₃@Ni Fe LDH composite perovskite as an electrocatalyst for Oxygen EvolutionIn this chapter,a microwave-assisted hydrothermal process was used to synthesize LaNiO₃@Ni Fe LDH composite catalyst,and compared with the catalyst made by ordinary hydrothermal method,it was found that the microwave-assisted hydrothermal method could significantly improve its OER performance.The prepared LNO@Ni Fe LDH-M1 had good electrocatalytic activity.At a current density of 10 m A/cm²,the overpotential to OER was only 274 m V,and the Tafel slope was only 144m V/dec,demonstrating the rapid reaction kinetics and the improved inherent electrocatalytic activity.The excellent long-term durability of LNO@Ni Fe LDH-M1 under alkaline conditions was also crucial to the practical application of electrolyzed water.The improvement of its electrocatalytic activity came from a series of catalytic effects brought about by the heterostructure formed by LaNiO₃and Ni Fe LDH:excellent electrical conductivity,synergistic effect of enriching active sites,large electrochemical active area,and good auxiliary heating effect of microwave.