Electrochemical CO2/CO reduction on Ag/Cu electrodes and exploring minor Fischer–Tropsch reaction pathways

Abstract

Ag/Cu hybrids have emerged as highly efficient catalysts for electrochemical (EC) CO2 reduction, yielding impressive C–C coupling products. We investigate Ag/Cu electrodes prepared via sputter deposition to explore their potential in EC CO2 and CO reductions. Our study highlights the significant impact of Ag thickness on resulting gas and liquid products, emphasizing the vital role of the Ag/Cu interface. Under CO2-saturated conditions, CO, CH4, and C2H4 are produced with high Faradaic efficiencies, while CO2-saturated KHCO3 generates formate, ethanol, propanol, isopropanol, acetate, and acetone. Experiments in phosphate conditions reveal new pathways for long-chain hydrocarbons (CnH2n and CnH2n+2, n = 2–7), typical products of Fischer-Tropsch chemistry. We also demonstrate CO hydrogenation to CH4 and C2-7 hydrocarbons, with alkane/alkene ratios influenced by electrolyte nature, concentration, applied potential, and Ag-modified Cu. These insights have implications for energy, environmental applications, and the future of EC CO2 and CO reduction through C–C coupling.