2D-2D Heterojunctions of a Covalent Triazine Framework with a Triphenylphosphine-Based Covalent Organic Framework for Efficient Photocatalytic Hydrogen Evolution

To solve serious energy and environmental crises caused by rapid industrial development, the formation of heterostructured photocatalysts is a promising approach for efficient and scalable H-2 production from water splitting. In this study, a strategy for the synthesis of triphenylphosphine-based covalent organic framework (P-COF-1)/covalent triazine framework (CTF) 2D-2D heterojunctions via intermolecular pi-pi interactions has been reported. The experimental results show that the H-2 production rate of the 5% P-COF-1/CTF heterojunction exhibits 14,100 mu mol h(-1) g(-1), which is 2.5-2.6 times as much as that of pure CTF and the mechanical mixture (5% P-COF-1 + CTF). Based on the results of characterization and theoretical calculations, a possible mechanism to well explain the enhanced photocatalytic performance of the Type II heterojunction system has been proposed. The present work provides an idea to construct highly efficient and stable COF/CTF all-organic heterojunctions, and this strategy broadens the application range of COF/CTF-based heterojunction materials easily by adjusting the composition and structure of COF materials.