A green synthetic approach for self-doped TiO2 with exposed highly reactive facets showing efficient CO2 photoreduction under simulated solar light

Abstract

Doping with oxygen vacancies and Ti³⁺ and engineering of the crystal morphology for exposing highly reactive facets have been demonstrated as important approaches to decrease the band gap of TiO₂ and establish surface heterojunctions to enhance the photocatalytic performance of TiO₂ under simulated solar light. The highly reactive facets can impact not only the CO₂ reduction but also the TiO₂ modification. Herein, atmospheric pressure dielectric barrier discharge (DBD) cold plasma, a green method with no environmentally hazardous reducing agents, was developed to achieve the self-doping of a TiO₂ single crystal film with exposed highly reactive facets. This method combines the advantages of the special facets and crystal defects. The characterization results indicate that the DBD cold plasma method achieves the modification of the TiO₂ film. The samples show remarkable improvement in reducing CO₂ and H₂O to CO and CH₄ under simulated solar light, with yields reaching 0.075 micromol per m² and 0.015 micromol per m², respectively. The formation mechanisms of the method for TiO₂ modification and CO₂ reduction are also discussed.