An Intimate Heterojunction Architecture: Linear Conjugated Polymer Confinement Within Covalent Organic Framework Pores for Enhanced Photocatalytic Hydrogen Peroxide Production.

Construction of a heterojunction to promote exciton dissociation is widely pursued in photocatalyst design, and the interfacial area is one of the critical factors that must be considered. To date, covalent organic framework (COF) photocatalytic heterojunctions mainly rely on their crystal outer surface as an interface, while overlooking the extensive surface area provided by internal pore walls. Here, we report a COF pore wall-based heterojunction design achieved by in situ confinement of linear conjugated polymers (LCPs) within COF pores via concurrent growth in copolymerization of a four-aldehyde-functionalized pyrene monomer, a two-amine-functionalized benzene monomer, and a two-aldehyde-functionalized benzothiadiazole monomer. The optimized COF/LCP hybrid displays enhanced charge carrier generation, lifetime, and transport, resulting in a significant improvement in photocatalytic H2O2 production performance (209%-enhancement vs. COF, 75%-enhancement vs. LCP, and 99%-enhancement vs. COF/LCP physical mixture). The established heterojunction has been proven to efficiently promote electron transfer from COF to LCP, thereby opening new avenues in high-performance photocatalyst design.