Surface Reconstruction of Facet-Functionalized SrTiO₃ Nanocrystals for Photocatalytic Hydrogen Evolution

The surface structure determines the surface electronic and chemical properties of semiconducting nanocrystals for efficient photocatalysis. Herein, SrTiO₃ nanocrystals enclosed by {0 0 1} and {0 2 3} facets functionalized for photoreduction and photooxidation, respectively, were surface-reconstructed with a disordered overlayer created by a thermal hydrogenation process. These surface-reconstructed SrTiO₃ nanocrystals showed much higher photocatalytic activities than the pristine SrTiO₃, which was attributed to the enhanced charge transfer ability and accelerated oxidative reaction kinetics induced by the oxygen vacancies in disordered overlayer. Given the maintained {0 0 1} and {0 2 3} facets ensuring spatial charge separation and functioning for reduction and oxidation reactions, respectively, the surface-reconstructed SrTiO₃ nanocrystals enclosed with {0 2 3} and {0 0 1} facets in appropriate ratio showed the highest photocatalytic activity for hydrogen evolution.