Abstract: In view of the difficulty of complete mineralization of volatile organic compounds in indoor air and the technical difficulties of practical application of traditional powder photocatalysts, an all-solid-state self-supporting WO₃-CeO₂ heterojunction photocatalyst was prepared and applied to photocatalytic removal of a typical indoor contaminant, formaldehyde, with high mineralization rate. In WO₃-CeO₂, the WO₃ nanowire was prepared through a hydrothermal coupling with calcination method by using three dimension W net as substrate, and the CeO₂ was further precipitated on it by hydrothermal method. The unique WO₃ nanowire-like structure helps capture formaldehyde dispersed in the air. The internal electric field formed at the interface of CeO₂ and WO₃ heterojunction can effectively drive the separation of photogenerated electron pairs, and produce a large number of active free radicals (·O₂^-, ·OH) to degrade formaldehyde efficiently. Under the irradiation of simulated sunlight, the prepared WO₃-CeO₂ photocatalyst can make 66.96 mg/m³ formaldehyde almost completely mineralized into CO₂ and H₂O within 60 min. In addition, due to the stable physical and chemical properties and the variable valence electric pair of CeO₂ and WO₃, the catalytic activity of the photocatalyst decreased only 2.1% after 10 consecutive degradation of formaldehyde, showing good catalytic stability. This work will provide scientific reference for the development of indoor formaldehyde removal technology.entific reference for the development of indoor formaldehyde removal technology.