Single-crystal SrTiO3 hollow sphere with ultrathin shell for efficient photocatalytic water splitting

• • UTSS-STO achieves a 2.5-fold increase in photocatalytic hydrogen evolution rate relative to mesoporous STO single crystals (MS-STO), directly translating to higher hydrogen productivity per unit mass of catalyst. • • The ultrathin shell shortens charge transport lengths and provides highly accessible active surfaces, reducing bulk recombination and enhancing surface reaction kinetics. • • Interlayer stress in the curved shell, combined with an optimized electronic band structure, facilitates charge separation, as evidenced by improved photocatalytic activity. • • Uniform distribution of ultrafine Rh/Cr2O3 cocatalyst particles on both inner and outer surfaces of the hollow shell maximizes active site utilization, contributing to the enhanced reactivity.