The Study On The Electrochemical Performance Of LaFeO₃-based Nanoparticles

Because perovskite materials have higher structural tolerance,and compared with traditional noble metal catalysts,doped perovskite materials have very high performance improvement potential and lower cost.These advantages make perovskite materials have good development prospects.In the field of green energy such as fuel cells,pollutant degradation,and water electrolysis,the oxygen reduction(ORR)reaction and oxygen evolution(OER)reaction are the core.Until now,platinum and platinum alloys have been the most effective oxygen-reducing catalysts.However,platinum and platinum alloys,as precious metals,have very high costs and low reserves,all of which make the application of materials expensive and unable to be commercialized.At the same time,the catalytic stability of platinum and platinum alloys is very low.After multiple reactions,an oxide film is easily formed to hinder the progress of the catalytic reaction,and platinum and platinum alloys do not haveOER performance.Metal oxides such as ruthenium oxide and iridium oxide have highOER activity.However,these materials have poorORR performance and are expensive and cannot be applied on a large scale.The performance defects of these electrocatalytic materials,the high cost of preparation,and the scarcity of raw materials make them unable to be used in real life.Therefore,finding a material that can replace the above expensive catalysts in large-scale production,has relatively good catalytic performance,and has excellent stability has become the focus of research at this stage.The perovskite structure material is easy to adjust because of its structure,and after adjustment,it has the potential to improve in various performances.This excellent quality makes it a research focus in the field of electrocatalysis.Due to the high stability of the perovskite structure,other valence metal cations can be used to replace the ions in the A and B positions to form structural defects such as anions(oxygen vacancies),cation vacancies,and lattice distortion to improve the catalytic performance of the perovskite materials.In this article,we successfully prepared La_1-xBi_xFeO₃ and La_1-xFeO_3-?nanoparticles by controlling the ratio of the element types of A-site ions and the sintering atmosphere using the sol-gel method.Through the test and analysis of the phase structure and electrochemical performance,the influence of various conditions on the electrochemical performance of the material is determined.We tested the electrochemical performance of La_1-xBi_xFeO₃ nanoparticles prepared in an air atmosphere and found that theORR andOER performance of the material at this time were greatly improved compared to La FeO₃.Among them,La_0.85Bi_0.15FeO₃ has relatively best electrochemical performance.However,when the doping amount is 0.2,the electrochemical performance of the material decreases.The main reason is that the material has obvious agglomeration,which reduces the specific surface area that can participate in the reaction and slows the charge transfer of the material.Therefore,although the doping of Bi element is beneficial to the improvement of the electrochemical performance of the material,it cannot be over-doped.In this experiment,the doping amount is 0.15 as a more suitable doping concentration.The electrochemical performance test of La_1-xBi_xFeO₃ nanoparticles annealed in a vacuum atmosphere found that the materials annealed in a vacuum atmosphere are prone to generate miscellaneous phases,and the material agglomeration phenomenon is very serious,which makes the specific surface area of the material that can participate in the reaction is very small,and the charge The transfer is relatively slow,therefore,the vacuum atmosphere is not suitable as a method to provide oxygen vacancies for the material.The electrochemical performance test of La_1-xFeO_3-?nanoparticles annealed in air atmosphere found that the material has the most excellent specific surface area and strong charge transfer ability.Among them,La_0.9FeO_3-?nanoparticles show the bestORR,OER performance.Therefore,adjusting the content of A-site elements within a certain range is an effective way to optimize the crystal structure of perovskite materials,enhance surface oxygen vacancies,and enhance their electrochemical performance.