Boosting photocatalytic multi-VOCs decontamination over COF-based heterojunction via targeted construction of Ov–M–N charge channel (M = Ti, Zn, W, Ce) and –NH₂ functionalization

Abstract

Covalent organic frameworks (COF) based materials have exhibited excellent gas and visible light absorption capability, yet are very difficult to generate strong oxidative species for photocatalytic mineralization of volatile organic compounds (VOCs). Here, a facile in situ modulation protocol developed could enable the growth of MOx (M = Ti, Zn, W, Ce) with oxygen vacancy (Ov) on –NH2-functionalized COF surfaces to construct NH2–COF/Ov–MOx Z–scheme heterojunctions of excellent stability and efficiency (98.3 %) in photo-oxidation of formaldehyde, acetaldehyde, and acetone. The –NH2 functionalization enhanced VOC chemisorption via H-bond interaction. Moreover, the constructed fast charge transfer channel (Ov–M–N) at the interface not only promoted directional migration of photo-excited carrier, activated adsorbed O2 and H2O to quickly generate strong •OH, but also effectively inhibited injurant formation to realize the precise control of the conversion path. These findings offer new insights into customizing the interfacial structure of COF for indoor air purification.