Modulated electronic structure and directed charge transfer in CuCo-CdS/C for enhanced photocatalytic CO2 reduction

Carbon dioxide (CO₂) photoreduction has aroused great interest. However, the photocatalysts for CO₂ photoreduction still face challenges of low catalytic efficiency and poor stability. Although the charge transfer in the catalyst can promote the charge redistribution and the activation of CO₂ molecules thereby improving the CO₂ photoreduction efficiency, the charge transfer mechanism, depending on the element, the coordination environment, the substrate type, and active atomic space, is very complex. In this study, photocatalysts made of CdS and CuCo heteroatom-doped carbon (CuCo-CdS/C) were synthesized with a metal–organic framework as the precursor. The catalytic performance of the synthesized CuCo-CdS/C catalysts for CO₂ photoreduction was evaluated; and their photocatalytic mechanism was examined by means of density functional theory computations, in situ X-ray photoelectron spectroscopy, and in situ diffused reflectance infrared fourier transform spectroscopy. The experimental results show that CuCo-CdS/C has strong catalytic activity and good stability towards CO₂ photoreduction, providing CO yield of 63.34 µmol g⁻¹h⁻¹ which remains nearly unchanged after 5 cycle of reuse. This is closely related to photocatalytic mechanism associated with light-generated electron/hole redistribution on the photocatalyst surface. Namely, CdS attracts electrons from CuCo diatom and accumulates electrons to form the electron-rich active sites for CO₂ photoreduction. At the same time, the d-band center of the catalyst shifts upward to significantly enhance photocatalytic CO₂ reduction. This approach, hopefully, is to provide new insights into the design of highly active and efficient photocatalytic systems for CO₂ photoreduction.