La0.7Sr0.3MnO3 Perovskites for Oxygen Reduction in Zn-Air Batteries: Enhanced by In Situ Glucose Regulation.

Abstract

The actual ORR catalytic activity of perovskite materials is significantly lower than the theoretical value due to their inherently low specific surface area and significant segregation of inactive oxygen ions on the surface. This study reports a sol-gel synthesis approach that employs glucose as a structural regulator to fabricate La_0.7Sr_0.3MnO₃ (LSM) perovskites. Compared with the original LSM (12.56 m²·g^-1), LSM-Y2 exhibits a higher specific surface area (19.43 m²·g^-1) and enhanced ORR catalytic activity. Electrochemical results show that the initial potential and half-wave potential of LSM-Y2 are positively shifted by 35 and 85 mV, respectively, with a 1.29-fold increase in intrinsic catalytic activity. Additionally, the performance of the Zn-air batteries is superior to that of the original LSM, with a peak power density of 115 mW·cm^-2 and an energy density of 858 Wh·kg^-1. The enhanced ORR catalytic activity of LSM-Y2 is attributed to the optimization of Mn e_g orbital occupancy on the catalyst surface, facilitated by glucose introduction, and the improved adsorption of oxygen intermediates, resulting from the increased oxygen vacancy concentration. Additionally, the increased specific surface area and porosity of LSM-Y2 provided more active sites for the catalytic process, further enhancing ORR performance. This study not only elucidates the mechanism by which glucose influences the ORR catalytic activity of La_0.7Sr_0.3MnO₃ perovskite but also presents a strategy for developing perovskite catalysts with superior ORR catalytic performance.