Surface self-modification of TiO2 for enhanced photocatalytic toluene oxidation via photothermal effect

Abstract

Surface modification plays an important role in extending light absorption and enhancing the catalytic performance of semiconductor photocatalysts. However, most current studies focus on pre-modification of the semiconductors before reaction, while surface self-modification of catalyst during photocatalytic reaction process is often neglected. Here, we report the surface self-modification of TiO₂ catalyst during photocatalytic oxidation of toluene under UV light irradiation, which changes the colour of TiO₂ from white to yellow, and effectively extends its light absorption range into visible light region. The absorbed visible light is primarily released as thermal energy, significantly increasing the temperature of the catalytic system. Mechanistic studies reveal that the temperature elevation facilitates the separation of photogenerated charge carriers in TiO₂ and promotes the generation of •O₂⁻, consequently accelerating the surface redox reactions. The surface self-modified TiO₂ exhibits an enhanced photothermal catalytic benzaldehyde generation of 4485 μmol g⁻¹ h⁻¹ under UV–visible light irradiation, which surpasses the UV-driven activity by a factor of 1.9. This study offers new perspectives on the surface modification of semiconductor photocatalysts during organic transformations. It is anticipated to trigger increased research attention to this effect, ultimately advancing solar-to-chemical energy conversion.