Steering the products distribution of CO2 electrolysis: A perspective on extrinsic tuning knobs

Using renewable electricity to electrochemically convert CO2 into value-added chemicals and fuels is a promising way to curb anthropogenic carbon emissions. In past years, exciting achievements have been witnessed on the robust and selective electrochemical CO2 reduction reaction, via either the delicate design of electrocatalytic materials or the local reaction environment engineering toward a practical system integration. In this perspective, we overview recent advances of extrinsic reaction environment effects in promoting CO2-to-C2+ conversion from three spatial aspects: (1) the chemical and physical surface modification, (2) the electrolyte composition and adjoint concentration gradient for both cations and anions, and (3) the mass transport regulation. Prevailing hypotheses, together with experimental and/or theoretical progress, have been critically assessed along with a deepened mechanism understanding of those extrinsic tuning knobs. Finally, challenges and future opportunities for more efficient C2+ production are provided in terms of fundamental interface engineering and technical electrolyzer implementation.