S-scheme heterojunction Bi2MoO6/WO3 toward efficient photocatalytic oxidation of indoor gaseous formaldehyde under indoor temperature, humidity and sunlight irradiation conditions

Abstract

Volatile organic compounds (VOCs) represent the primary pollutants in indoor air, exerting a significant impact on the quality of this environment and human health. Herein, the S-scheme heterojunction photocatalyst Bi₂MoO₆/WO₃ was prepared by grafting nano WO₃ thin block onto the nanoflower spheres surface of Bi₂MoO₆, which exhibited efficient photocatalytic oxidation of HCHO (600ppm) under simulated sunlight. Bi₂MoO₆/WO₃-3 has the best photocatalytic oxidation effect on HCHO, with a kinetic constant of 5.5 min^-1 g^-1, which is 25 times and 26 times higher than that of Bi₂MoO₆ and WO₃ single-phase materials, respectively. And the material has excellent moisture resistance, stability and universality. The electron transfer mechanism and catalytic mechanism were further explored in depth by photoelectrochemical performance tests and DFT calculations. The photocatalyst has been shown to effectively separate the photogenerated carriers and generate active species such as hydroxyl radicals (•OH) and superoxide radicals (•O₂^-). This study provides a novel approach to the design of efficient heterojunction photocatalysts for the effective degradation of VOCs under sunlight.