Assembling ultrathin nickel hydroxide nanosheets on cadmium sulfide hollow spheres for enhanced CO2 photoreduction

The controllable hollow sphere, serving as an excellent light-trapping cavity, represents one of the most appealing structures in photocatalytic CO2 reduction but is plagued by limited catalytic active sites. Herein, we report an in situ self-assembly strategy to decorate cadmium sulfide hollow spheres (CdS HS) with ultrathin nickel hydroxide (Ni(OH)2) nanosheets to boost CO2 photoreduction. The as-grown CdS@Ni(OH)2 photocatalyst affords a higher CO yield of 3.12 mmol g-1h−1 and a good apparent quantum efficiency (AQE) of 2.05 % compared with the pristine CdS HS (0.38 mmol g-1h−1). The superior performance could be assigned to the unique hollow nanostructure and the synergistic effect between CdS HS and Ni(OH)2 nanosheets. The interior CdS HS strengthens the multiple light reflections that leads to optimized light harvesting. The ultrathin Ni(OH)2 nanosheet shell effectively prevents photocorrosion of CdS while providing a suitable local chemical environment that promotes CO2 adsorption and activation. Additionally, the close contact interface of CdS@Ni(OH)2 facilitates efficient separation and migration of photoinduced electrons and holes, thus boosting photocatalytic kinetics. This study presents a facile route for the controllable engineering of hollow microreactors toward CO2 photoreduction and sheds light on the structure-dependent photocatalytic mechanisms.