Direct electrochemical conversion of CO2 to ethanol offers a promising strategy to lower CO2 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 CO2-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 Cun clusters (n = 3 and 4) on application of electrochemical conditions. First-principles calculations further elucidate the possible catalytic mechanism of CO2 reduction over Cun.
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This material is based on work supported by Laboratory Directed Research and Development funding from Argonne National Laboratory, provided by the Director, Office of Science, of the US Department of Energy (DOE) under contract no. DE-AC02-06CH11357. The works performed at Argonne National Laboratory’s Center for Nanoscale Materials and APS, US DOE Office of Science User Facilities, are supported by Office of Science, US DOE under contract no. DE-AC02-06CH11357. Part of the DFT calculations were also performed using the computational resources provided by the Laboratory Computing Resource Center at the Argonne National Laboratory. T.X. acknowledges the financial support from the XSD visiting scientist program at APS at Argonne. C.L.’s work is supported by the US DOE, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, under contract no. DE-AC02-06CH11357 (Argonne National Laboratory). The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof; neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, nor usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. We also acknowledge I. Hwang for verification of our EXAFS simulation by Artemis.
An US patent application (US 2019/0276943 A1) on amalgamated metal—Li catalyst synthesis for CO2 conversion with D.-J. Liu, T. Xu, H. Xu and D. Rebollar as the coinventors was filed by UCHICAGO ARGONNE, LLC. The authors declare no other competing interests.
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Xu, H., Rebollar, D., He, H. et al. Highly selective electrocatalytic CO2 reduction to ethanol by metallic clusters dynamically formed from atomically dispersed copper. Nat Energy 5, 623–632 (2020). https://doi.org/10.1038/s41560-020-0666-x