Cubic structured SrTiO₃ with Ce/Cr Co-doping for photoinduced catalytic oxidation of gaseous mercury

A cubic SrTiO₃ (STO) composite material co-doped with Ce and Cr ions was synthesized by solvothermal method. The fully characterized samples were employed as photocatalysts for the oxidation of Hg⁰. The co-doped samples afforded excellent catalytic removal efficiency of 98.99% using UV irradiation and 89.9% using visible light irradiation for Hg⁰ compared with the single-doped samples. It was found that co-doped samples had a lower electron-hole recombination rate, largest Brunauer-Emmett-Teller specific surface area, and reduced band gap. The electron spin resonance results revealed that ·O₂^- and ·OH were the main active species in the catalytic process. Moreover, the co-doped samples exhibited the best electron transfer rate and the highest photocurrent response intensity. The electron transfer between the elements in the co-doped sample enables it to achieve stable and efficient catalytic performance. In addition, even after five consecutive catalytic runs, the co-doped sample maintained high catalytic activity. This work highlights the potential of the perovskite-type STO materials in the photocatalytic oxidation of gaseous mercury.