Abstract
The perspective of developing two-step CO2 electrolytic systems, combining electroreduction of CO2 to CO and electroreduction of CO to a desired organic compound, requires the availability of catalysts and flow cell electrolyzers to achieve the second step with high selectivity and low overpotentials. Here, via optimization of porous dendritic copper materials based on nine different samples, using different acidic conditions for copper electrodeposition and including a calcination step in some cases, we report a unique catalyst that allows, within a gas diffusion electrode and a flow cell, CO electroreduction to ethylene with a very high record faradic efficiency of 78%. Such a system functions with a record half-cell energy efficiency of 40.5%. Based on this value, electrical energy efficiency for CO2 conversion to ethylene can be calculated using literature data for a CO2-to-CO solid oxide electrolysis cell, yielding 37%, the highest value reported so far.