Fig. 2: The CO₂ release performance on Cu in H cell.

CO₂ release-cyclic voltammetry for A Cu foil and B Cu nanoparticles in 0.1 M KA (A = Cl⁻, NO₃⁻ and ClO₄⁻) supporting electrolyte with 0.1 M EDA-CO₂ carbamates in H cell. All the CVs were recorded at 5 mV s⁻¹. The average resistance of Cu foil in 0.1 M EDA-CO₂ electrolyte containing 0.1 M KCl, KNO₃ and KClO₄ at 25 °C was 5.4, 5.5 and 5.4 Ω, respectively. For Cu nps, the corresponding values were 6.6, 6.5, and 6.4 Ω. All CV curves were recorded without iR correction. Arrows indicated the onset potentials for Cu oxidation extracted from the voltammograms, and the numerical voltage labels denoted the corresponding onset values (vs. Ag/AgCl) for each supporting electrolyte. The arrow at 0.08 V (vs. Ag/AgCl) showed a distinct oxidation peak uniquely observed in the KCl + EDA–CO₂ electrolyte.