Abstract:

The oxygen evolution reaction (OER) is considered the rate-limiting step in electrochemical water splitting, and has been widely used to solve energy and environmental issues. Perovskite oxides (ABO₃) exhibit good OER activity, owing to their tunable electronic structures and highly flexible elemental compositions. However, the preparation of perovskite oxides usually requires long exposure to high temperatures, resulting in metal agglomeration and undesirable effects on intrinsic activity. Vapor-phase microwave technology can significantly reduce the duration of heat treatment and subsequently reduce the associated carbon emissions. This technology not only addresses the growing demand for carbon-neutral processes but also enables increased control of the synthesis to avoid undesirable agglomeration of the product. In this study, a 2D porous La_0.2Sr_0.8CoO₃ perovskite was rapidly prepared using a microwave shock method. The rapid entropy increase associated with the microwave process can effectively expose abundant active sites in the La_0.2Sr_0.8CoO₃ structure. Furthermore, the high-energy microwave shock process can precisely introduce Sr²⁺ into the lattice of LaCoO₃, increasing the number of oxygen vacancies by increasing the oxidation state of Co. The oxygen vacancies introduced by replacing La with Sr can considerably improve the intrinsic catalytic activity of the material. For the OER in alkaline electrolytes, the prepared La_0.2Sr_0.8CoO₃ catalyst displayed an excellent overpotential of 360 mV at 10 mA·cm⁻² and a Tafel slope of 76.6 mV·dec⁻¹. After a long-term cycle test of 30000 s, 97% of the initial current density was maintained. This study presents a facile and rapid strategy for the synthesis of highly active 2D perovskites.

Key words: Two-dimensional, Perovskite, Microwave, Oxygen vacancy, Oxygen evolution reaction