Efficient Electroreduction of High-Pressure Gaseous and Supercritical CO2 to CO in a Zero-Gap Electrolyzer

The electroreduction of carbon dioxide (CO2R) presents a promising avenue for mitigating CO2 emissions while producing valuable chemicals. In this work, we report a novel pressure equilibrium strategy tailored for pressurized CO2R in a zero-gap electrolyzer, aiming at accommodating the high-pressure CO2 sources from its capture, utilization, and storage scheme. We investigated the impact of pressure on the CO2R performance under both gaseous and supercritical conditions, while also examining the synergistic interplay of temperature with high pressure. Significant enhancement of energy efficiency (46.5%) with high CO Faradaic efficiency (94.4%) and low cell voltage (−2.72 V) was achieved at 200 mA/cm2 under 75 bar and 80 °C. In addition, we noticed that the agglomeration and migration of salt precipitation within the gas diffusion electrode were effectively suppressed under pressurized conditions, which indicated the potential benefit for prolonged cell stability.