Temperature-dependent selectivity for CO electroreduction on copper-based gas-diffusion electrodes at high current densities

The electroreduction of carbon monoxide (CO) on copper (Cu) in aqueous media is known to generate industrially relevant C2 + chemicals. CO originating from a CO2 capture source combined with CO electrolysis, powered with renewable energy and water, provides us with a method of producing green chemicals. However, the industrial applicability of this technology is still in the nascent stage. In this work, we explore the boundaries of what can realistically be achieved with the current state-of-the-art technology, to gauge the feasibility of employing CO reduction as a means of carbon valorization in an industrial setting, focusing on ethylene and ethanol as products of interest due to their market size and value. In this study commercial heterogeneous electrocatalysts were analyzed, applied on a GDL to form a GDE and then ranked with respect to ethylene and ethanol FE. Subsequently, the limits of production rate and single pass conversion were evaluated, and the effect of temperature on product selectivity investigated. Finally, durability under industrially relevant conditions was studied. We found that it is possible to operate at current densities of up to −2500 mA cm-2 without any appreciable increase in the faradaic yield towards hydrogen, yielding a total FE to C2 + products of 87 % and an ethylene FE of 35 %. We also demonstrate that temperature has a (positive) influence on the FE for ethylene, at the cost of a reduction in acetate formation. Additionally, we show that single pass conversions of up to 89 % can be achieved without loss of FE towards C2 + products. However, despite these promising results, we also show that catalyst durability remains a key challenge for long-term industrial operation of CO electroreduction.