Highly selective electrocatalytic CO2 reduction to ethanol by metallic clusters dynamically formed from atomically dispersed copper

• Published in: Nature energy 2020-08, Vol.5 (8), p.623-632
• Main Authors: Xu, Haiping, Rebollar, Dominic, He, Haiying, Chong, Lina, Liu, Yuzi, Liu, Cong, Sun, Cheng-Jun, Li, Tao, Muntean, John V., Winans, Randall E., Liu, Di-Jia, Xu, Tao
• Format: Article
• Language: English
• Subjects: 639/301/299/886; 639/4077/909/4101/4102; 639/638/161; Absorption spectroscopy; Carbon dioxide; Carbon dioxide emissions; Catalysts; Chemical synthesis; Clusters; Copper; Copper converters; Dispersion; Economics and Management; Electrocatalysts; Electrochemistry; Electrodes; Energy; Energy Policy; Energy Storage; Energy Systems; Ethanol; First principles; Hydrogen; Renewable and Green Energy; Selectivity; X ray absorption; X-ray absorption spectroscopy
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-020-0666-x

Direct electrochemical conversion of CO 2 to ethanol offers a promising strategy to lower CO 2 emissions while storing energy from renewable electricity. However, current electrocatalysts offer only limited selectivity toward ethanol. Here we report a carbon-supported copper (Cu) catalyst, synthesized by an amalgamated Cu–Li method, that achieves a single-product Faradaic efficiency (FE) of 91% at −0.7 V (versus the reversible hydrogen electrode) and onset potential as low as −0.4 V (reversible hydrogen electrode) for electrocatalytic CO 2 -to-ethanol conversion. The catalyst operated stably over 16 h. The FE of ethanol was highly sensitive to the initial dispersion of Cu atoms and decreased significantly when CuO and large Cu clusters become predominant species. Operando X-ray absorption spectroscopy identified a reversible transformation from atomically dispersed Cu atoms to Cu n clusters ( n  = 3 and 4) on application of electrochemical conditions. First-principles calculations further elucidate the possible catalytic mechanism of CO 2 reduction over Cu n . Electrocatalytically reducing CO 2 to ethanol can provide renewably generated fuel, but catalysts are often poorly selective for this conversion. Here the authors use a Cu catalyst to produce ethanol with high selectivity. Cu dispersion is key to the performance and operando studies indicate that it changes under reaction conditions.