An etching-coordination strategy to construct yolk–shell structured ZIF/Fe–tannic acid composites for enhancing photothermal catalytic CO2 cycloaddition

Highly efficient carbon dioxide (CO2) conversion over novel photothermal catalysts featuring a wide light absorption range to meet the energy and chemical demands is an urgent challenge. To this end, an etching-coordination strategy is designed to synthesize novel metal–organic framework/metal–tannic acid (TA) composites for photodriven CO2 cycloaddition. ZIF-8 can be partially removed by TA to yield a yolk–shell structure, facilitating multiple reflections of light and thereby improving light utilization and photothermal conversion. With the aid of coordination between the Fe3+ and –OH groups, the formation of Fe–TA networks on the surface of ZIF-8 significantly enhances its photoresponsive range. Notably, under full-spectrum illumination of 550 mW cm−2 for 10 h, ZIF-8/Fe–TA-10 achieves a catalytic yield of 96.3% with >99.9% selectivity for the coupling of CO2 and epichlorohydrin. Furthermore, the calculation results suggest that CO2 cycloaddition can be accelerated with a significantly reduced activation energy (19.4 kJ mol−1) in the presence of ZIF-8/Fe–TA-10. On the basis of the experimental results, a cooperative reaction mechanism coupling photothermal catalysis and photocatalysis is proposed. This work provides an available strategy for the future synthesis of MOF-based photocatalysts for catalytic and other applications.