SrTiO3 single crystals enclosed with high-indexed {0 2 3} facets and {0 0 1} facets for photocatalytic hydrogen and oxygen evolution

• SrTiO3 nanocrystals enclosed with {0 2 3} and {0 0 1} facets were synthesized.
• {0 2 3} facets provided active sites for photocatalytic oxygen evolution.
• {0 0 1} facets provided active sites for photocatalytic hydrogen evolution.
• Photocatalytic activity was optimized by tuning the ratio of {0 0 1} to {0 2 3} facets.

SrTiO3 single crystals enclosed with high-indexed {0 2 3} facets and {0 0 1} facets were facilely synthesized via a one-pot solvothermal method. The ratio of {0 2 3} to {0 0 1} 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 {0 2 3} to {0 0 1} facet. The highest photocatalytic activities are achieved for SrTiO3 single crystals with the ratio of {0 2 3} to {0 0 1} facet tuned to 35:65, with hydrogen and oxygen evolution rates reaching 71.1 and 30.0 μmol/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 {0 2 3} facets provided active sites for photo-oxidation reaction, while the {0 0 1} 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.

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