Unraveling the photo-induced dynamic behavior of COF-based Z-scheme heterostructure monolithic aerogels

Abstract

Covalent organic framework (COF)-based Z-scheme heterostructures are great potential photocatalysts, while they are usually limited by the sluggish photo-induced dynamic behavior at the interface of the heterostructure. Herein, a COF-based Z-scheme heterostructure monolithic aerogel, consisting of hydroxy-functionalized COFs (OH−COF) and poly(terpyridine)metal complex (Re-CP), is designed. Benefiting from the perfect match between the size of terpyridine unit and the pore aperture of OH−COF, the CH···O interactions between OH−COF and Re-CP are achieved. Meanwhile, chemical bonds can be formed between Re ions of Re-CP and C=N groups of OH−COF. The construction of multiple interactions at the heterojunction interface can provide multiple charge transport pathways, increase the strength of the built-in electric field, and minimize the exciton binding energy, which achieves ultrafast charge transfer and generates more long-lived free charge carriers (up to 46.9 ns of the average life) for photoredox reactions. The heterostructural aerogel exhibits a high photocatalytic activity in gas-solid CO₂ reduction.