Cadmium sulfides: Electrochemical CO2 reduction and Fischer–Tropsch synthesis pathways

Abstract

The development of electrocatalysts is a pivotal aspect of advancing electrochemical (EC) CO2 recycling. In this research, we incorporated cadmium sulfide (CdS) onto a cadmium (Cd) support and subsequently enhanced it with the deposition of Au, Ag, and Cu using sputter deposition techniques. These modified catalysts were then rigorously evaluated for their performance in EC CO2 reduction. The primary products were formate, CO, and H2. Notably, CdS/Cd demonstrated significantly superior performance in EC CO2 reduction compared to the unmodified Cd catalyst. Furthermore, the deposition of transition metals drastically suppressed H2 production, while Ag and Cu deposition enhanced CO production in NaHCO3 conditions. For Au/CdS/Cd in phosphate condition, CH4 and alkane-dominant C2–7 hydrocarbons were significantly produced and explained by the conventional Fischer–Tropsch synthesis paths. After EC CO2 reduction, CdS/Cd surface was observed to be recrystallized to CdCO3 with a morphology of cubes. Photocatalytic CO2 reduction over CdS/Cd produced CO, CH4, CH3OH, and alkene-dominant C2–6 hydrocarbons. Additionally, a zinc sulfide (ZnS) on Zn electrode was prepared and tested, which showed H2 and CO as main products, but no formate was observed.