Hybridization of covalent organic frameworks and photosensitive metal‐organic rings: A new strategy for constructing supramolecular Z‐scheme heterostructures for ultrahigh photocatalytic hydrogen evolution

Abstract

Abstract The rational design of Z‐scheme heterojunction photosystems based on covalent organic frameworks (COFs) is a promising strategy for harnessing solar energy for hydrogen conversion. Herein, a direct Z‐scheme single‐atom photocatalyst based on COF and metal‐organic ring has been constructed through the supramolecular interactions of coral‐like COF (S‐COF) and photosensitized Pd2L2 type metal‐organic ring (MAC‐FA1). The MAC‐FA1/S‐COF heterojunction exhibits good light absorption, efficient charge separation and transfer, slow electron‐hole recombination, and highly dispersed Pd active sites, enabling an efficient and stable H2 evolution reaction. The optimized 4% MAC‐FA1/S‐COF achieves an H2 evolution rate of 100 mmol g−1 h−1 within 5 h and obtains a total accumulated turn‐over number relative to Pd (TONPd) of 437,685 within 20 h, far superior to S‐COF, MAC‐FA1, M‐5/S‐COF, Pd/S‐COF, and M‐5/Pd/S‐COF, which is one of the highest records among COF‐based photocatalysts for solar‐driven H2 evolution. This is the first work to incorporate photosensitized metal‐organic rings/cages into porous crystalline COFs to form a supramolecular Z‐scheme heterojunction, which has significant potential as a high‐performance photocatalyst for solar‐driven H2 production.

Keywords

• covalent organic framework
• metal‐organic ring
• single‐atom catalyst
• visible‐light‐driven H2 production
• Z‐scheme heterojunction