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

Perovskites 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 degrees C for 2 h, the Co exsolved perovskite catalyst (R-LCTCo0.11) exhibits optimal OER performance. The mass activity of R-LCTCo0.11 reaches approximate to 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 eta = 470 mV). Electrochemical impedance spectroscopy (EIS) data reveals that R-LCTCo0.11 has the lowest charge transfer resistance (Rct = 58 omega), 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. The oxygen evolution reaction (OER) performance of Ti-based perovskite can be enhanced by exsolving Co nanoparticles, which are surface-anchored onto the parent perovskite. This exsolution process effectively prevents nanoparticle agglomeration and improves atom utilization efficiency, leading to significantly higher mass activity. Specifically, the mass activity of R-LCTCo0.11 is found to be 17-times higher than that of LCTCo0.11 at eta = 450 mV.image