Polyquinone Modification Promotes CO2 Activation and Conversion to C2+ Products over Copper Electrode

Electrocatalytic CO2 reduction to value-added chemicals is a promising route to address the global warming problem. However, it still confronts low conversion efficiency and poor selectivity, due to difficulties in activating the inert CO2 molecule and controlling the complex reaction pathways. Here, we put forward an unconventional approach to activating CO2 by utilizing the quasi-reversible bonding between electrochemically reduced quinone groups and CO2. Through surface modification with polyquinone, the C2+ production is effectively enhanced on a polycrystalline Cu foil model electrode. By further incorporating the polyquinone into a Cu gas diffusion electrode (GDE), a high C2H4 partial current density of 325 mA/cm2 is achieved at a low cell voltage of 3.5 V for CO2/pure water coelectrolysis. Combined with in situ ATR-SEIRAS study, the increased C2+ product selectivity is attributed to the quinone-accelerated CO2-to-*CO conversion, which creates a high *CO coverage on Cu surface and thus facilitates C–C coupling for C2+ production.