Electrocatalysis is often viewed as an alternative method for performing energy-intensive thermochemical reactions, such as reducing nitrogen to form ammonia (Haber–Bosch process) or CO2 reduction to ethylene. Temperature is an often-used tool in catalytic reactions, helping overcome considerable kinetic barriers. However, the combination of increased temperatures and electrocatalysis is underexplored, due to difficulties in cell design.

Previous studies on high-temperature electrochemical CO2 reduction with copper electrodes have shown variable selectivity and activity of C2+ product formation. Bare Cu electrodes enhance CO2 and H+ reduction activity at increased temperatures, but no substantial improvement has been noted for current densities and onset potentials for C2+ formation. However, promising results were obtained by Gregoire and co-workers when Cu surfaces were coated with diphenyliodonium by electro-polymerization. The same robust polyaromatic coating has been shown to enhance C2+ formation — instead of producing H2 — for room-temperature electrocatalysis with Cu electrodes. Interestingly, as the surface temperature increased, the modified Cu electrode demonstrated an enhanced partial current for C2+ products. Also, the observed positive shift in the onset potential for C–C bond formation indicates that increasing temperature offsets the excess electrical potential required for electrocatalysis Optimum results were achieved at 60 °C and –1.02 V versus a reversible hydrogen electrode, with 44% Faradaic efficiency for C2+ formation and a partial current density of 6.61 mA cm–2. This translates to a gain in 0.1 V overpotential as compared to the same experiment with the electrode at room temperature.