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Copper nanoparticle ensembles for selective electroreduction of CO2to C2–C3products

  • Author(s): Kim, D
  • Kley, CS
  • Li, Y
  • Yang, P
  • et al.
Abstract

© 2017, National Academy of Sciences. All rights reserved. Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective formation of C2–C3products at low overpotentials. Densely packed Cu NP ensembles underwent structural transformation during electrolysis into electrocatalytically active cube-like particles intermixed with smaller nanoparticles. Ethylene, ethanol, and n-propanol are the major C2–C3products with onset potential at −0.53 V (vs. reversible hydrogen electrode, RHE) and C2–C3faradaic efficiency (FE) reaching 50% at only −0.75 V. Thus, the catalyst exhibits selective generation of C2–C3hydrocarbons and oxygenates at considerably lowered overpotentials in neutral pH aqueous media. In addition, this approach suggests new opportunities in realizing multicarbon product formation from CO2, where the majority of efforts has been to use oxidized copper-based materials. Robust catalytic performance is demonstrated by 10 h of stable operation with C2–C3current density 10 mA/cm2(at −0.75 V), rendering it attractive for solar-to-fuel applications. Tafel analysis suggests reductive CO coupling as a rate determining step for C2products, while n-propanol (C3) production seems to have a discrete pathway.

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