SrTiO₃ single crystals enclosed with high-indexed {023} facets and {001} facets for photocatalytic hydrogen and oxygen evolution

SrTiO₃ single crystals enclosed with high-indexed {023} facets and {001} facets were facilely synthesized via a one-pot solvothermal method. The ratio of {023} to {001} facets could be simply adjusted by tuning the NaOH and EA concentrations during the solvothermal growth process. It was demonstrated that the photocatalytic activities of the variously shaped SrTiO₃ should be closely related to the morphology of SrTiO₃, i.e., the ratio of {023} to {001} facet. The highest photocatalytic activities are achieved for SrTiO₃ single crystals with the ratio of {023} to {001} facet tuned to 35:65, with hydrogen and oxygen evolution rates reaching 71.1 and 30.0μmol/h, respectively, which are about 9.5 and 3.0 times higher than those of the irregular SrTiO₃ particles. Facet selective photo-deposition of metal ions reveals that the high-indexed {023} facets provided active sites for photo-oxidation reaction, while the {001} facets offered active sites for photo-reduction reaction. Such spatially separated photoactive reduction and oxidation sites should benefit charge separation in a SrTiO₃ single crystal, leading to higher photocatalytic activity related to the irregular SrTiO₃ particles.