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

Abstract

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+2x Ca0.7-2x Ti1-x Cox O3 perovskite and applied in OER. Upon reduction in the 5% H2 /N2 atmosphere at 800°C for 2h, the Co exsolved perovskite catalyst (R-LCTCo0.11) exhibits optimal OER performance. The mass activity of R-LCTCo0.11 reaches ≈1700mAmg-1 at an overpotential of 450mV, which is 17 times and 3 times higher than that of LCTCo0.11 (97mAmg-1 ) and R-Mix (560mAmg-1 ) catalysts respectively, surpassing the benchmark catalyst RuO2 (42.7mAmg-1 of oxide at η=470mV). Electrochemical impedance spectroscopy (EIS) data reveals that R-LCTCo0.11 has the lowest charge transfer resistance (Rct =58Ω), demonstrating the highest catalytic and kinetic activity for OER. Furthermore, this catalyst shows high stability during an accelerated durability test of 10h 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.