In Situ Spectroscopic Evaluation of Copper Corrosion during Electroreduction of CO2–Amine Adducts

Abstract This work experimentally investigated the corrosion of a copper working electrode during the direct electrochemical conversion of captured CO2 sources under basic conditions. The effect of using ammonium carbamate or dimethyl ammonium dimethyl carbamate as the captured CO2 source on the observed corrosion was studied using bulk electrolysis (BE) and UV–vis or EPR spectroscopy conducted simultaneously for 24–48 h over a range of applied voltages and captured CO2 source concentrations. Over time during BE, a maximum in the absorbance was observed at 650 nm in the UV–vis, along with the formation of a blue color, and the appearance of an S = 1/2 signal detected in a flow spectroelectrochemical EPR system. The spectroelectrochemical experiments enabled the kinetics of the electrode corrosion to be evaluated. A distinct difference in rates was observed for ammonium carbamate vs dimethyl ammonium dimethyl carbamate. Characterization of the copper electrode prior to and post BE by atomic force microscopy, powder X-ray diffraction, and scanning electron microscopy indicated a rough surface that became smooth, with an increase in Cu(II) and oxide formation over time. Combined, these data offer insights towards copper electrode corrosion in the presence of amine-based captured CO2 sources.