Dissecting the interfaces of MOF-coated CdS on synergized charge transfer for enhanced photocatalytic CO2 reduction

Photocatalytic CO2 reduction mimicking the nature photosynthetic process has been long desired by researchers for closing the carbon cycle, and relies on the exquisite design of efficient photocatalytic systems. Herein, MOF of Co(BDC) is employed to bridge the heterogeneous CdS photosensitizer and molecular co-catalyst [Co(bpy)3]2+ for promoting photocatalytic CO2 reduction reactions (CO2RR), resulting in a remarkable CO yield rate of 22 μmol h−1 and selectivity of 92.5%. Accordingly, the turnover number is 7.3 (4 h) with an apparent quantum yield about 0.7% at λ = 420 nm. Through a comprehensive kinetic and spectroscopic study, we show the improved photocatalytic CO2RR performance profits from highly efficient charge transfer at both the CdS/MOF and MOF/solution interfaces, in between the MOF layer serves as a reaction platform for expediting both the charge and mass kinetics of the triphasic solid-liquid-gas reaction, apart from further protecting the photosensitizer from photo-corrosion. The knowledge gained here can be generalized to guide future design of more efficient hybrid photocatalytic systems.