Angewandte Chemie International Edition · 2017 · 403 citations · 28 references
Natural SciencesChemical EngineeringChemistryCatalysisElectrochemistryInorganic ChemistryCatalyst CharacterizationCatalyst StabilityCatalyst SynthesisCatalytic MaterialsMetal OxidesRedox CatalysisCo OxidationCopper CatalysisCopper-catalyzed OxidationMetal Oxide CatalysisMetal Oxide Catalyst SynthesisMetal Oxide CatalystsOxygen Content AnalysisSelectivity
Abstract 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.
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