Electrocatalytic Performance Investigation Of Double Perovskite Gd Ba Co₂O_5+δ Oxrgen Electrodes

With the rapid development of society,the demand for energy has greatly increased.Therefore,we need to develop clean,efficient and sustainable electrochemical energy storage and conversion equipment to meet the sustainable growth of society.Such as metal-air batteries,fuel cells and electrolytic cells.However,the kinetics of the oxygen reduction reaction（ORR）and oxygen evolution reaction（OER）that dominate these devices are relatively slow,thus limiting the development of such energy devices.The development of effective bifunction catalysts has become the main goal of electrochemical energy storage and conversion technology.In recent years,double perovskites have received ext ensive attention due to their excellent performance,low cost and stability.In this paper,the double perovskite GdBaCo₂O_5+δ（GBCO）was quenched and doped with Sr to improve its bifunctional catalytic performance and stability.In this paper,GBCO was synthesized by solid-phase method and quenched at 700℃,800℃ and 900℃ to obtain GBCO700,GBCO800 and GBCO900.ORR,OER and stability of GBGO and its quenching materials were tested using rotating disk electrode and electrochemical workstation.Then applied th em to oxygen electrodes of solid oxide fuel cell（SOFC）,and impedance spectroscopy,polarization curve and stability were tested.In addition,GBCO was doped with Sr at the Ba site to obtain GBSCO,and was further quenched.At the same time,electrochemic al tests and comparative studies were conducted on them.Finally,we analysed the mechanism by SEM,XPS,etc.By testing the catalytic performance of GBCO and quenched materials,it is found that quenching treatment improves the bifunctional catalytic performance of the material,and GBCO800 has the best performance.It has the largest current density at the same potential,the largest ORR half-wave potential,the smallest OER overpotential and the minimum ORR and OER Tafel slope,and the quenching treatment makes the ORR transfer electron number of the GBCO oxygen electrode closer to 4.In addition,GBCO800 has excellent stability in an alkaline environment.After 1000 cycles of CV,the decline rate is only 2%.Applying GBCO and quenching materials to SOFC,it was shown that GBCO800 has the smallest impedance value and activation energy value within the temperature range of 500℃～700℃.According to the polarization curve,GBCO800 has the largest current density at the same potential.In the process of cathodi c polarization treatment,GBCO800 is less affected by polarization.It shows that quenching treatment makes GBCO more excellent as a SOFC oxygen electrode.The catalytic performance test results of GBSCO shown that the doping of Sr improves the catalytic performance of the material,the ORR half-wave potential increases,the number of transferred electrons is closer to 4,the OER overpotential decreases,and the slopes of ORR and OER Tafel are reduced.After a long-term CV cycle scan,the decline rate of GBSCO is only 2%.Finally,we combined the two optimization methods to quench GBSCO.The test results showed that the ORR half-wave potential was further increased,the OER overpotential was further reduced,and the ORR and OER Tafel slopes were further reduced.And after a long period of cyclic scanning,the decline rate is only 1.5%.Its catalytic performance and stability have been further improved.