Boosting molecular oxygen activation of SrTiO3 by engineering exposed facets for highly efficient photocatalytic oxidation

Abstract

Engineering exposed facets for improving the activation of molecular oxygen into O₂˙⁻ species and charge separation is a promising way to improve photocatalytic oxidation activity. Herein, SrTiO₃ nanocrystals with controllably exposed {001} and {110} facets are prepared as a proof-of-concept candidate to study the effect of exposed facets on the activation of molecular oxygen into O₂˙⁻ species, finally acting on the photocatalytic oxidation of gaseous HCHO. The photocatalytic test demonstrates that {110} facet exposed SrTiO₃ nanoparticles present a HCHO photocatalytic degradation rate about 6.8 times faster than that of the {001} facet exposed one. The experiments and theoretical calculations together confirm that as compared to the {001} facet exposed sample, the {110} facet exposed sample is favorable for activating molecular oxygen to produce O₂˙⁻ species under the irradiation of light, owing to the relatively higher conduction band position and lower surface adsorption energy for O₂ molecules as well as advantageous charge accumulation on adsorbed O₂ molecules. Finally, the new production of O₂˙⁻ species and the higher charge separation contribute to the superior HCHO photocatalytic oxidation activity of {110} facet exposed SrTiO₃. This interesting finding is probably useful for the design of highly efficient single crystal photocatalysts for photocatalytic oxidation reactions.