Stepped {110} Facet-Enriched Ga³⁺-Doped SrTiO₃ Crystal Nanoparticles for Enhanced Photocatalytic Overall Water Splitting Reaction

For the SrTiO3 semiconductor, the oxygen evolution reaction (OER) remains the rate-determining step in photocatalytic overall water splitting, indicating the key role in efficiently improving the exposure of OER-active crystal facets highly associated with the water oxidation kinetics. Herein, we design a Ga3+ ion incorporation in SrTiO3 crystal to etch the surface through flux treatment, with the formation of highly exposed stepped {110} facets. The formation mechanism and its impact on photocatalytic performance were systematically investigated by various characterization techniques and density functional theory (DFT) calculations. The related findings reveal that the unique stepped surface facets play a crucial role in reshaping surface charge distribution and remodulating defect states, thereby contributing to the enhanced photocatalytic performance. Upon loading with cocatalysts, the Ga3+-doped SrTiO3 featuring stepped structures exhibits outstanding photocatalytic performance, achieving a solar-to-hydrogen (STH) efficiency of 0.48% and an apparent quantum yield (AQY) of 80.91% at 365 nm, with H2 and O2 evolution rates of 1.43 and 0.72 mmol·h–1, respectively. This work highlights the synergistic modulation of facet engineering and defect engineering in photocatalysts.