Effects of Elevated Temperatures and Catalyst Layer Morphology on the Carbon Balance during Electrochemical CO Reduction

The electrochemical reduction of carbon monoxide (CORR) offers a promising opportunity to convert renewable electricity into value-added C2+ chemicals, such as ethylene, ethanol, and acetate. While scaled electrolyzer systems are expected to operate at elevated temperatures, the impact of temperature on crossover during CORR remains underexplored. In this study, we systematically evaluate the influence of temperature (25–85 °C) on the CORR using various copper-based catalyst layers, cell configurations (flow-by and anion exchange zero-gap membrane cell), and processing conditions (anolyte concentration, current density, and temperature). At low current density (−50 mA cm–2), product selectivity is found to be insensitive to temperature across the full investigated range. In addition, elevated temperatures significantly suppress the crossover of liquid products to the anolyte, thus, improving the net carbon efficiency. At higher current densities, conventional sputtered Cu electrodes suffer from severe flooding and CO starvation, limiting performance and selectivity. To address this, spray-coated Cu/PTFE electrodes are introduced, combining porosity and hydrophobicity to stabilize performance. These electrodes enable study of the CORR at current densities and temperatures of up to 400 mA cm–2 and 85 °C, respectively. Overall, the study shows that the temperature primarily affects product transport rather than reaction pathways. Understanding thermal effects is critical for guiding the design of CORR systems capable of efficient, stable operation under thermally and industrially realistic conditions.