Elemental Doping Induced Sulfur Vacancies Enable Efficient Electrochemical Reduction of CO2 over CdS Nanorods

The electrochemical reduction of CO2 suffered from the large energy loss induced by the Ohmic loss of electrocatalysts and the large barrier for CO2 activation. Herein, we incorporated the monovalent Ag+ into CdS nanorods, so as to integrate the elemental doping and sulfur vacancies (S-vacancies) for boosted electrochemical reduction of CO2. Specifically, the doping of Ag+ accompanied by the formation of S-vacancies due to the conservation of charge. At −1.1 V versus RHE, the Ag-doped CdS (Ag-CdS1–x) nanorods exhibited a considerable current density of 53.7 mA cm–2 with a maximum Faradaic efficiency (FE) for CO production of 87.1%, which significantly overperformed the performance of pristine CdS nanorods and CdS1–x nanorods with a similar concentration of S-vacancies. A mechanistic study revealed that the Ag doping increased the carrier density of CdS nanorods by 3.1 times, together with the S-vacancies strengthened the binding of CO2 over electrocatalysts. The combination of promoted conductivity and facilitated CO2 activation accounted for the efficient electrochemical reduction of CO2 over Ag-CdS1–x nanorods.