Improving the Oxygen Evolution Reaction: Exsolved Cobalt Nanoparticles on Titanate Perovskite Catalyst

Abstract

AbstractPerovskites are an important class of oxygen evolution reaction (OER) catalysts due to highly tunable compositions and adaptable characteristics. However, perovskite‐based catalysts can have limited atom utilization efficiency due to large particle size, resulting in low mass activity. Herein, Cobalt nanoparticles are exsolved from La0.2+2xCa0.7‐2xTi1‐xCoxO3 perovskite and applied in OER. Upon reduction in the 5% H2/N2 atmosphere at 800 °C for 2 h, the Co exsolved perovskite catalyst (R‐LCTCo0.11) exhibits optimal OER performance. The mass activity of R‐LCTCo0.11 reaches ≈1700 mA mg−1 at an overpotential of 450 mV, which is 17 times and 3 times higher than that of LCTCo0.11 (97 mA mg−1) and R‐Mix (560 mA mg−1) catalysts respectively, surpassing the benchmark catalyst RuO2 (42.7 mA mg−1 of oxide at η = 470 mV). Electrochemical impedance spectroscopy (EIS) data reveals that R‐LCTCo0.11 has the lowest charge transfer resistance (Rct = 58 Ω), demonstrating the highest catalytic and kinetic activity for OER. Furthermore, this catalyst shows high stability during an accelerated durability test of 10 h electrolysis and 1000 cycles cyclic voltammetry (CV). This work demonstrates that nanoparticle exsolution from a doped perovskite is an effective strategy for improving the atom utilization efficiency in OER.