Hierarchical porous structured biomass based COFs for photocatalytic oxidative coupling of amines

Abstract

Covalent Organic Frameworks (COFs) are widely used for photocatalysis but limited by the aggregation of the catalysts, which limited the mass transfer. Herein, corn stalk cores were used as the substrate, and two kinds of biomass based COFs with different electronic structures of thiophene (C@SCOF) and pyridine (C@NCOF) were in-situ fabricated uniformly on the surface of the substrate. In this way, COFs expose more active sites rather than embedding in the agglomerated structure. Biomass based COFs, especially C@SCOF, exhibit a hierarchical porous structure containing micropores and macropores, which offer fast mass transfer channels for the catalytic and adsorbed substrates. Therefore, the biomass based COFs utilized more efficiently to achieve higher photocatalytic performance. The C@SCOF with D-A structure displays stronger photoresponse and lower impedance, which promote the dissociation of a photogenerated exciton and carrier separation efficiency, resulting remarkable photocatalytic performance for oxidation of benzylamine coupling reaction. This work could guide the design and preparation of biomass-based hybrids with promising performance.