Exploring B‐site Doping in LaFeO3 Perovskites for Superior ORR Performance in Acidic and Alkaline Conditions

Abstract

AbstractIn recent times, perovskite oxides have recognized to be an ideal alternative to platinum‐based oxygen reduction reaction (ORR) electrocatalysts due to their excellent stability, cost‐effectiveness, and tailorable properties. Herein, an ABO3 type LaFeO3 perovskite was doped at its B‐site to form electrochemically active LaFeB′O6 (B′=Cr, Zn, Co) by one‐pot hydrothermal synthesis process. Due to the synergistic effects of increased surface area and electrochemically active sites, Cr‐doped LaFeO3 largely improves the mass transfer kinetics for ORR in both conditions, alkaline (0.1 M KOH) and acidic (0.5 M H2SO4) with a positive onset Eon of 0.80 and 0.81 V (vs Ag/AgCl). Similarly, a half‐wave (E1/2) potential of 0.68 and 0.63 V (vs Ag/AgCl), which was comparable to the commercial 20 % Pt/C. Moreover, the La‐based perovskites were able to catalyze ORR with an electron transfer number (n)>3.6 signifying the superior 4‐electron pathway. Doped and undoped LaFeO3 exhibited remarkable stability in the chronoamperometry studies with a relative current of 92–95 % sustained over 8 h. Additionally, the La‐based electrocatalysts was unaffected by the crossover effect of methanol in both acidic and basic conditions, contrary to the commercial 20 % Pt/C. The present work serves as a useful strategy to maximize the efficiency and reliability in perovskites for energy‐related electrocatalytic applications and for alternative fuel generation.