Enhanced visible-light properties of TiO2/diatomite composite over varied bismuth semiconductors modification for formaldehyde photodegradation: A comparative study

• Bi 2 MoO 6 , BiOCl and BiVO 4 are used to construct heterojunctions with TiO 2 /diatomite. • Three high-efficient adsorption-photocatalysis collaborative system was constructed. • Bi 2 MoO 6 modified TiO 2 /diatomite has the optimal performance. • Diatomite is the foundation of constructing adsorption-catalysis collaborative system. How to improve the photocatalytic performance of titania-based photocatalyst under visible light in environmental remediation remains a challenge. Herein, three kinds of bismuth semiconductors, including Bi 2 MoO 6 , BiOCl and BiVO 4 , are selected to construct heterojunctions with diatomite supporting titania for improving photocatalytic performance towards formaldehyde (HCHO) under visible light. The morphologies and microstructures as well as the photocatalytic performance of the as-received samples are systematically investigated for comparation. The Bi 2 MoO 6 -TiO 2 /diatomite (MTD-50) composite has the optimal performance, followed by BiOCl-TiO 2 /diatomite (CTD-100) composite and BiVO 4 -TiO 2 /diatomite (VTD-75) composite, whose mineralization rate is up to around 47.58 times, 29.55 times and 21.14 times that of TiO 2 /diatomite (TD) composite, respectively. Moreover, the performance enhancement mechanism could be attributed to their relatively high quantum efficiency that originated from the heterojunctions, resulting in the high generation efficiency of active radicals. This work would like to compare bismuth semiconductor photocatalysts for enhancing visible-light properties through heterojunction and provide comparative references for developing novel visible light driven photocatalysts in the field of indoor HCHO purification.