CO2 electroreduction to C2 products on bimetallic silver copper melamine complexes

Abstract

Nanocube crystals of bimetallic Ag-Cu-Melamine molecular complexes have been originally developed as effective electrocatalysts for the CO2 selective reduction to multicarbon products, particularly ethylene and ethanol. The bimetallic complex, containing 10 wt.% Ag demonstrates the highest performance in electro-reduction of CO2 in both H-type and flow cells. It achieves a Faradaic efficiency of 70 % for C2 products, with 40 % attributed to ethanol and the remaining to ethylene. These results are obtained at a cathode potential of -1.0 V vs reversible hydrogen electrode (RHE) with a total current density of -50 mA·cm-2 in the flow cell, five times higher current densities than the current densities in the H-Cell. Without Ag in the complex, only C1 products (CO and formic acid) are detected. The use of the flow cell, in addition to higher current densities, enhances C2 formation, especially ethylene, which is absent in H-type cell experiments. These novel electrocatalysts also exhibit stable performances and provide mechanistic indications of the roles of Ag and tandem cooperation with Cu.