Dual-Anion-Stabilized Cu^δ+ Sites in Cu₂(OH)₂CO₃ for High C₂₊ Selectivity in the CO₂ Electroreduction Reaction

The excessive emission of CO₂ has aroused increasingly serious environmental problems. Electrochemical CO₂ reduction reaction (CO₂RR) is an effective way to reduce CO₂ concentration and simultaneously produce highly valued chemicals and fuels. Cu^δ+ species are regarded as promising active sites to obtain multi-carbon compounds in CO₂RR, however, they are easily reduced to Cu⁰ during the reaction and fail to retain the satisfying selectivity for C₂₊ products. Herein, via a one-step method, we synthesize Cu₂(OH)₂CO₃ microspheres composed of nanosheets, which has achieved a superior Faraday efficiency for C₂₊ products as high as 76.29 % at -1.55 V vs. RHE in an H cell and 78.07 % at -100 mA cm^-2 in a flow cell. Electrochemical measurements, in situ Raman spectra and attenuated total reflectance infrared spectra (ATR-IR) as well as the theoretic calculation unveil that, compared with Cu(OH)₂ and CuO, the dual O-containing anionic groups (OH^- and CO₃ ^2-) in Cu₂(OH)₂CO₃ can effectively stabilize the Cu^δ+ species, promote the adsorption and activation of CO₂, boost the coverage of *CO and the coupling of *CO-*COH, thus sustain the flourishment of C₂₊ products.