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Stability of Residual Oxides in Oxide‐Derived Copper Catalysts for Electrochemical CO 2 Reduction Investigated with 18 O Labeling
Author(s) -
Lum Yanwei,
Ager Joel W.
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201710590
Subject(s) - catalysis , chemistry , selectivity , electrochemistry , oxide , inorganic chemistry , copper , aqueous solution , carbon fibers , electrode , materials science , biochemistry , organic chemistry , composite number , composite material
Oxide‐derived (OD) Cu catalysts have high selectivity towards the formation of multi‐carbon products (C 2 /C 3 ) for aqueous electrochemical CO 2 reduction (CO 2 R). 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 synthesizing 18 O‐enriched OD Cu catalysts and testing them for CO 2 R. These catalysts maintain a high selectivity towards C 2 /C 3 products (ca. 60 %) for up to 5 h in 0.1 m KHCO 3 at −1.0 V vs. RHE. However, secondary‐ion mass spectrometry measurements show that only a small fraction (<1 %) of the original 18 O content remains, showing that residual oxides are not present in significant amounts during CO 2 R. Furthermore, we show that OD Cu can reoxidize rapidly, which could compromise the accuracy of ex situ methods for determining the true oxygen content.