Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Formaldehyde (HCHO), as one of the main indoor toxic pollutions, presents a great threat to human health. Hence, it is imperative to efficiently remove HCHO and create a good indoor living environment for people. Herein, a layered perovskite material SrBi2Ta2O9 (SBT), was studied for the first time and exhibited superior photocatalytic efficiency and stability compared to commercial TiO2 (P25). Furthermore, a unique dark–light tandem catalytic mechanism was constructed. In the dark reaction stage, HCHO (Lewis base) site was adsorbed on the terminal (Bi2O2)2+ layer (Lewis acid) site of SBT in the form of Lewis acid-base complexation and was gradually oxidized to CO32− intermediate (HCHO → DOM (dioxymethylene) → HCOO− → CO32−). Then, in the light reaction stage, CO32− was completely converted into CO2 and H2O (CO32− → CO2). Our study contributes to a thorough comprehension of the photocatalytic oxidation of HCHO and points out its potential for day–night continuous work applications in a natural environment.