Solution plasma engineering the surface of nitrogen doped TiO2 for photothermal catalysis

Abstract

Surficial electron traps have significant effects on the trapping, release, transport, and interfacial transfer of electrons in the photocatalytic process. In this work, we attempted to employ a solution plasma treatment to modify the surface of commercially available nitrogen-doped TiO2 (N-TiO2) and modulate the surficial electron traps. By tuning different kinds of bubbled gas and time for solution plasma treatment, the energy level distribution of surficial electron traps could be optimized, which was revealed with reversed double-beam photoacoustic spectroscopy (RDB-PAS). Through a typical O2-bubbled solution plasma treatment of N-TiO2 for two hours, the mineralization rate of the photocatalytic degradation of acetaldehyde reached nearly 100% at 333 K, and the rate of acetaldehyde degradation increased by 3.2 times. An RDB-PAS analysis demonstrated that the O2-bubbled solution plasma treatment worked by introducing surficial electron traps with a shallow energy level below the conduction band minimum, bringing a higher reduction ability for photogenerated electrons and thus contributing to the enhanced performance of photocatalysis. This work highlighted the fact that solution plasma was effective for modifying the material surface and modulating the surficial electron traps for photocatalyst activation.