Perovskite Oxides: Synthesis Strategies and Advances in Photoelectrocatalytic Applications

The depletion of fossil fuels and the resulting environmental burden have increased interest in photocatalytic routes for converting solar energy into storable chemical energy. Their overall performance depends strongly on the intrinsic physicochemical properties of the photoanode material. Conventional wide-bandgap semiconductors are limited by restricted visible-light absorption and rapid charge-carrier recombination that lowers quantum efficiency and hinders practical implementation. Perovskite oxides offer adjustable crystal structures, flexible metal valence states and useful redox properties, making them promising candidates for addressing these critical limitations. This review examines the crystal structures and photocatalytic mechanisms of perovskite oxides and compares how sol–gel, solid-state, coprecipitation, and hydrothermal synthesis affect grain size, microstructure, and surface defects. It also discusses their emerging applications in electrocatalytic nitrate reduction to ammonia and photocatalytic selective oxidation of organic substrates. The review relates synthesis conditions to carrier separation and surface reaction barriers, providing a solid basis for designing stable, efficient photocatalytic systems toward scalable solar-to-chemical conversion.