Direct low concentration CO2 electroreduction to multicarbon products via rate-determining step tuning

Direct converting low concentration CO2 in industrial exhaust gases to high-value multi-carbon products via renewable-energy-powered electrochemical catalysis provides a sustainable strategy for CO2 utilization with minimized CO2 separation and purification capital and energy cost. Nonetheless, the electrocatalytic conversion of dilute CO2 into value-added chemicals (C2+ products, e.g., ethylene) is frequently impeded by low CO2 conversion rate and weak carbon intermediates' surface adsorption strength. Here, we fabricate a range of Cu catalysts comprising fine-tuned Cu(111)/Cu2O(111) interface boundary density crystal structures aimed at optimizing rate-determining step and decreasing the thermodynamic barriers of intermediates' adsorption. Utilizing interface boundary engineering, we attain a Faradaic efficiency of (51.9 ± 2.8) % and a partial current density of (34.5 ± 6.4) mA·cm−2 for C2+ products at a dilute CO2 feed condition (5% CO2 v/v), comparing to the state-of-art low concentration CO2 electrolysis. In contrast to the prevailing belief that the CO2 activation step ( $${{CO}}_{2}+{e}^{-}+\, * \,\to {}^{ * }{CO}_{2}^{-}$$ ) governs the reaction rate, we discover that, under dilute CO2 feed conditions, the rate-determining step shifts to the generation of *COOH ( $${}^{ * } {{CO}}_{2}^{-}+{H}_{2}O\to {}^{ * } {COOH}+{{OH}}^{-}({aq})$$ ) at the Cu0/Cu1+ interface boundary, resulting in a better C2+ production performance. The development of catalysts that operate under low concentration CO2 resembling industrial waste gases holds promise for CO2 reduction. Here, the authors report a vacuum calcination approach for regulating the Cu0/Cu1+ density on Cu-based catalysts that can electro-catalyze low-concentration CO2.