Well-defined CoS cages enable the separation of photoexcited charges to promote visible-light CO reduction.

Exploring affordable cocatalysts with high performance for boosting charge separation and CO activation is an effective strategy to reinforce CO photoreduction efficiency. Herein, well-defined CoS cages are exploited as a nonprecious promoter for visible-light CO reduction. The CoS cages are prepared a multistep strategy with ZIF-67 particles as the precursor and fully characterized by physicochemical techniques. The hollow CoS cocatalyst with a high surface area and profuse catalytically active centers is discovered to accelerate separation and transfer of light-induced charges, and strengthen concentration and activation of CO molecules. In a hybrid photosensitized system, these CoS cages efficiently promote the deoxygenative reduction of CO to generate CO, with a high yield rate of 35 μmol h (, 35 mmol h g). Besides, this cocatalyst is also of high stability for the CO photoreduction reaction. Density functional theory (DFT) calculations reveal that the Ru(bpy) photosensitizer is strongly absorbed on the CoS (311) surface through forming four Co-C bonds, which can serve as the "bridges" to ensure quick electron transfer from the excited photosensitiser to the active CoS cocatalyst, thus promoting the separation of photoexcited charges for ehannced CO reduction performance.