High-selectivity electroreduction of low-concentration CO2 with large concentration fluctuation

Abstract

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.