Abstract
Copper-based catalysts are notable for their ability to facilitate carbon-carbon (C–C) bond formation during the electrochemical reduction of CO2; however, their selectivity and stability are strongly dependent on surface structure and composition. In this study, copper and copper-silver composite structures were fabricated via electrochemical deposition onto a glassy carbon substrate in a solution containing lactic acid (LA) and sodium dodecyl sulfate (SDS). As the electrodeposition potential was shifted in the negative direction from –0.15 V to –0.35 V, the peak of the current transient moved to shorter times (tmax: 0.67 → 0.01 s), while the maximum current density increased (jmax: 7.15 → 36.36 mA·cm-2), indicating a higher nucleation density. Electrochemical measurements conducted in CO2-saturated 0.5 M NaHCO3 revealed that the copper-silver electrode exhibited superior catalytic performance compared to pure copper. Specifically, the Tafel slope decreased from 389 to 243 mV·dec-1, and the exchange current density (j0) increased by a factor of 17. Electrochemical impedance spectroscopy further demonstrated that the copper-silver electrode possessed a higher double-layer capacitance (Cdl = 4.39 μF) and a polarization resistance (Rp) that was 2.8 times lower than that of the pure copper electrode. Overall, the results indicate that incorporating silver into copper during electrochemical deposition significantly enhances the catalytic activity of the resulting material for the electrochemical reduction of carbon dioxide.