Electrocatalytic CO2 reduction in acidic medium

Electrocatalytic carbon dioxide (CO2) reduction has been considered as a promising pathway to achieve carbon neutrality. In alkaline or near-neutral medium, considerable catalytic activity has been reached. However, the inevitable reaction of CO2 molecules with hydroxide ions forms carbonates, leading to low energy efficiency and carbon utilization. CO2 electrolysis in acidic medium provides a viable alternative to reduce carbonate production and achieve low energy consumption for CO2 conversion due to the high carbon utilization and low overpotential for anodic oxygen evolution reaction. Herein, we discuss the progress for efficient electroreduction of CO2 in acidic medium, wherein theory-guided discovery of cations' actions, rational design of electrode/catalysts, and local pH effect together accelerate the achievement of acidic CO2 electroreduction. An outlook is provided about the future development of efficient acidic CO2 electrolysis, which concerns the catalyst/electrode design and catalytic microenvironment optimization for boosting the selectivity of C-C coupling.