Cu clusters immobilized on Cd-defective cadmium sulfide nano-rods towards photocatalytic CO2 reduction

Single-site metal atoms or clusters (SMCs) present high potential to enable the exploration of energetics and kinetics in heterogeneous photocatalysis owing to their unique properties. Here, we report the first work for highly no ligands-protected atomic-level Cu clusters by mediating them in Cd vacancies at the edge of CdS nanorods (CuCR SCC) towards photocatalytic CO2 conversion. X-ray absorption spectrometric analysis and photoelectric dynamic characterizations demonstrate that the well-defined Cu clusters across the Cd vacancies induce a synergistic effect on CO2 reduction through the interfacial conjunction, accelerating charge carrier mobility and facilitating atom utilization. In situ diffuse reflectance infrared Fourier transform spectroscopy, low-coverage calculated isosteric heat, and theoretical studies unveil that the direct cluster/substrate conjunction provides a driving force for interfacial electronic modification and dynamic cooperation. Besides, Cu acts as the active site in the process of CO2 photoreduction, which enhances the adsorption and activation of CO2. Consequently, this leads to outstanding CO2-to-CO conversion with a turnover number of more than 90 without the addition of any sacrificial agent. Particularly, the Cu clusters-mediated CdS nanorods are able to serve as carrier provider, allowing the photogenerated electrons transfer from CdS to Cu clusters. These electrons received from CdS can further enhance the charge carrier separation and thus achieve high photostability during longtime light irradiation.