Nanostructured Tungstate-Derived Copper for Hydrogen Evolution Reaction and Electroreduction of CO2 in Sodium Hydroxide Solutions

Electroreduction of CO2 became an important topic recently because it can reduce the atmospheric CO2 levels and simultaneously synthesize chemical fuels. However, efficient conversion of CO2 to produce fuels remains a challenge because a proper electrocatalyst is needed to make this CO2 reduction process more selective and efficient. In this study, we prepared nanostructured tungstate-derived copper to test its application in CO2 reduction. The prepared copper tungstate (CuWO4) nanomaterials were first characterized by analytical techniques such as transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy to determine the particle size, crystallinity, purity, and composition. Then, the CuWO4 nanomaterials were further investigated in an aqueous solution containing 0.1 M NaOH by electrochemical cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques. The CO2 electroreduction experiments were carried out in 0.1 M NaOH with the presence of CO2, and the analysis of electrochemical results shows that nanostructured CuWO4 performs better in comparison with CuO-a well-known electrocatalyst for reducing CO, to nongaseous carbon-containing products such as alcohols-because of poisoning effects of adsorbed CO, or its adsorbed-reduced intermediates on hydrogen evolution reaction. Our results also show that CO2-reduction intermediates adsorbed strongly on the surface of CuWO4, which increases the overpotential for hydrogen evolution reaction on the surface of CuWO 4 by as much as 230 mV against the 70 mV for CuO, at a current density of 0.8 mA cm(-2).