Catalytic Activity of Cu and Cu/sn Electrodes During CO2 Reduction from Aqueous Media

Abstract

In this work, we investigated the catalytic activity of copper-based electrodes during CO2 reduction from KHCO3 aqueous solutions. Copper electrodes, synthetized by the electrochemical reduction of thermally formed copper oxide (CuRE), or by decorating of CuRE with tin (CuRE/Sn) were tested. Moreover, commercial copper or tin foils have been used for comparison. Different electrochemical techniques such as cyclic voltammeteries and linear sweep voltammetries were adopted in order to derive information on the reductive processes and to characterise the behaviour of the electrodes. Higher cathodic currents were obtained using CuRE and CuRE/Sn with respect to commercial foils. Depending on the applied potential, lower faradic efficiency (FE) is obtained at CuRE/Sn rather than at CuRE, and a very high loading of Sn seems to be required to increase the FE by some percentage points. Interestingly, at the lowest investigated potential (-0.8 V), the presence of Sn, even at low amount, was able to catalyse the formic acid formation, with a FE of 14%.