Replacement of Ca by Ni in a Perovskite Titanate to Yield a Novel Perovskite Exsolution Architecture for Oxygen-Evolution Reactions

For efficient catalysis and electrocatalysis well-designed, high-surface-area support architectures covered with highly dispersed metal nanoparticles with good catalyst-support interactions are required. In situ grown Ni nanoparticles on perovskites have been recently reported to enhance catalytic activities in high-temperature systems such as solid oxide cells (SOCs). However, the micrometer-scale primary particles prepared by conventional solid-state reactions have limited surface area and tend to retain much of the active catalytic element within the bulk, limiting efficacy of such exsolution processes in low-temperature systems. Here, a new, highly efficient, solvothermal route is demonstrated to exsolution from smaller scale primary particles. Furthermore, unlike previous reports of B-site exsolution, it seems that the metal nanoparticles are exsolved from the A-site of these perovskites. The catalysts show large active site areas and strong metal-support interaction (SMSI), leading to ≈26% higher geometric activity (25 times higher mass activity with 1.4 V of E_on-set) and stability for oxygen-evolution reaction (OER) with only 0.72 µg base metal contents compared to typical 20 wt% Ni/C and even commercial 20 wt% Ir/C. The findings obtained here demonstrate the potential design and development of heterogeneous catalysts in various low-temperature electrochemical systems including alkaline fuel cells and metal–air batteries.