High-selectivityelectroreductionoflow-concentrationCO2withlargeconcentrationfluctuation<iclass="icon-zqcb"></i>

Electrochemical CO2 reduction reaction（CO2RR） has been regarded as one of the most promising solutions to achieving “zero carbon emission”. In most of the CO2RR-related studies, high-purity CO2 has been employed as the feed gas; however, in practice, CO2 is generally emitted in low concentrations, so it is of great significance to realize high-selectivity electroreduction of low-concentration CO2 with large concentration fluctuation. In this work, we constructed a dual-active-site catalyst and successfully achieved CO2 local enrichment and conversion for low-concentration CO2 . Operando experiments reveal that the catalyst has one type of site for activating CO2 and one type of site for binding the reaction intermediates. The dual-active-site catalyst displays a selectivity for formic acid consistently above 97% over a broad potential window（from-0.9 to-1.6 V vs.RHE）. Even when fed with a low-concentration CO2 stream（volume ratio from 50% down to 10%）, the dual-active-site catalyst could display high activity and selectivity（>91%）. In particular, the selectivity is still above 85% when the CO2 volume ratio is as low as 5%. This work offers a feasible route for converting low-concentration CO2 via a synergistic effect for dual-active-site catalysts.