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Open Access Publications from the University of California

Stability of Residual Oxides in Oxide-Derived Copper Catalysts for Electrochemical CO2Reduction Investigated with18O Labeling

  • Author(s): Lum, Y
  • Ager, JW
  • et al.

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Oxide-derived (OD) Cu catalysts have high selectivity towards the formation of multi-carbon products (C2/C3) for aqueous electrochemical CO2reduction (CO2R). It has been proposed that a large fraction of the initial oxide can be surprisingly resistant to reduction, and these residual oxides play a crucial catalytic role. The stability of residual oxides was investigated by synthesizing18O-enriched OD Cu catalysts and testing them for CO2R. These catalysts maintain a high selectivity towards C2/C3products (ca. 60 %) for up to 5 h in 0.1 m KHCO3at −1.0 V vs. RHE. However, secondary-ion mass spectrometry measurements show that only a small fraction (<1 %) of the original18O content remains, showing that residual oxides are not present in significant amounts during CO2R. Furthermore, we show that OD Cu can reoxidize rapidly, which could compromise the accuracy of ex situ methods for determining the true oxygen content.

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