Confinement engineering of metal clusters within covalent organic frameworks for enhanced photocatalytic hydrogen evolution

Photocatalytic hydrogen evolution using solar energy is a promising approach for sustainable energy conversion, yet homogeneous metal cluster catalysts often suffer from instability and inefficient charge separation. Herein, we report a confinement strategy by embedding bimetallic trinuclear Fe 2 M (M = Co, Ni, Zn) clusters into a thiazole-based covalent organic framework (COF). The resulting COF@Fe 2 M hybrids combine the redox activity of metal clusters with the photoactive and porous architecture of COFs. Among them, COF@Fe 2 Co exhibits the highest activity, achieving 93.16 mmol g −1 co h −1 of H 2 in a 10 h irradiation, 5.8 times that of the physical mixture. Spectroscopic and electrochemical studies reveal efficient interfacial charge transfer, while density functional theory (DFT) calculations show that the Fe 2 Co cluster has the most favorable electronic structure and hydrogen adsorption energy. This work offers a rational platform for designing efficient hybrid photocatalysts.