Synergistic Effect of Sr-O Divacancy and Exposing Facets in SrTiO3 Micro/Nano Particle: Accelerating Exciton Formation and Splitting, Highly Efficient Co2+ Photooxidation

As a typical perovskite-type crystal, polyhedral strontium titanate (SrTiO3) has shown anisotropic charge transport behavior in recent studies, however, the carrier transportation and transition of which has not been explained very clearly. This work present the existence of Sr and O divacancies in the novel rhombicuboctahedron SrTiO3 micro/nano particles (Sr1-xTiO3-x/TiO2-x) with exposing (100), (110) and (111) facets and the diameter of 300-700 nm synthesized via hydrothermal synthesis, and also summarizes the dissociation mechanism of self-trapped excitons (STEs) caused by the divacancy and facet effect. In addition, most importantly, the metastable STEs with ultra-low binding energy (E-b < 3 meV) under illumination are discovered. Combining the model of S-scheme heterojunction, a conversion mechanism of photoinduced carriers is proposed. The photocatalytic reaction of Co2+ is used as the probe reaction, and the unique Sr1-xTiO3-x/TiO2-x possesses a high photooxidation efficiency of Co2+, by which 70.3% of Co2+ is oxidized to Co3+ (CoOOH) in 5 min. This finding may provide a guideline for an optimal design of the photocatalytic materials for the recovery and extraction of metal ions based on SrTiO3