Liberating photocarriers in mesoporous single-crystalline SrTaO2N for efficient solar water splitting

Abstract Porous single-crystalline SrTaO2N, combining structural homogeneity and high porosity, afford a great promise as an active photocatalyst. The lack of grain boundaries in SrTaO2N porous single crystals (PSCs) enables fast photocarrier migration from bulk to the surface whilst the high porosity offers adequate accessible surface to perform photocatalytic reactions. In this work, we demonstrate a facile synthesis of SrTaO2N PSCs via a topotactic conversion route. These SrTaO2N PSCs deliver exceptional activity and stability for photocatalytic O2 production from water with a record-breaking apparent quantum efficiency as high as 17.9% at 420 ± 20 nm. Overall water splitting with H2/O2 equals 2 has also been attained in a Z-scheme system employing SrTaO2N PSCs as the O2-evolution moiety. These results signify a paradigm to improve photocatalytic performance based on PSCs, which extends the toolbox to achieve efficient solar water splitting over conventional photocatalysts.