Electroreduction of CO₂ to ethanol by electrochemically deposited Cu-lignin complexes on Ni foam electrodes

A low cost, non-toxic and highly selective catalyst based on a Cu-lignin molecular complex is developed for CO₂ electroreduction to ethanol. Ni foam (NF), Cu-Ni foam (Cu-NF) and Cu-lignin-Ni foam (Cu-lignin-NF) were prepared by a facile and reproducible electrochemical deposition method. The electrochemical CO₂ reduction activity of Cu-lignin-NF was found to be higher than Cu-NF. A maximum faradaic efficiency of 23.2 % with current density of 22.5 mA cm^-2 was obtained for Cu-lignin-NF at -0.80 V (vs. RHE) in 0.1 M Na₂SO₄ towards ethanol production. The enhancement of catalytic performance is attributed to the growth of the number of active sites and the change of oxidation states of Cu and NF due to the presence of lignin.