NiCuAg: An electrochemically-synthesised trimetallic stack for CO2 reduction

Abstract

Electrochemical CO2 reduction is a promising technique for the production of desirable hydrocarbons without the need to resort to fossil resources. However, high overpotentials and poor selectivity remain a challenge for CO2 electro-reduction, especially for deep reduction by more than two electrons. One apparently attractive approach for breaking the scaling relations caused by simultaneous CO2 reduction pathways and for achieving deeper reduction is the use of multi-metallic electrodes, where several promising metal catalysts are present in close proximity. Herein, noting the activity shown by Ni, Cu and Ag for CO2 electroreduction when used individually, we set out to synthesise a tri-metallic “stack” catalyst, NiCuAg, and then to test this for electrochemical CO2 reduction. The stack architecture was successfully generated and the trimetallic NiCuAg system did show improved Faradaic efficiency for the reduction of CO2 to formic acid when compared to the bare Ni and bimetallic NiCu controls under some select conditions. However, the two-layer NiCu stack and bare Ni exhibited consistently higher Faradaic efficiencies than NiCuAg for deeper CO2 electroreduction to methanol and ethanol, indicating that the combination of three individually promising metals does not necessarily translate into superior catalytic performance for deep carbon dioxide reduction. [Display omitted]