Enhanced photostability of cuprous oxide by lignin films on glassy carbon electrodes in the transformation of carbon dioxide

Abstract

Photoelectrochemical reduction of CO₂ was investigated on carbon electrodes modified with lignin and cuprous oxide. The electrodes were modified by electropolymerization of lignin and subsequent pulse electrodeposition of Cu₂O. Characterization of the electrodes was performed by SEM microscopy, Raman, IR-ATR and UV-visible spectroscopies, as well as electrochemical methods. Lignin films provide a micro-environment where Cu₂O is stabilized and also its reactivity is modified toward C–H–O containing compounds. The main products obtained from the reduction of CO₂ are formaldehyde, methyl formate and ethyl acetate, as detected and quantified by nuclear magnetic resonance and UV-Vis spectroscopy. Our results demonstrate that lignin is a good material for the formation and support of the electrodeposited Cu₂O, where the Cu₂O enables the potential use of solar energy for the photoelectrochemical reduction of CO₂ at low overpotentials.