Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/122459
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Type: Journal article
Title: Selectivity control for electrochemical CO2 reduction by charge redistribution on the surface of copper alloys
Author: Vasileff, A.
Zhi, X.
Xu, C.
Ge, L.
Jiao, Y.
Zheng, Y.
Qiao, S.Z.
Citation: ACS Catalysis, 2019; 9(10):9411-9417
Publisher: ACS Publications
Issue Date: 2019
ISSN: 2155-5435
2155-5435
Statement of
Responsibility: 
Anthony Vasileff, Xing Zhi, Chaochen Xu, Lei Ge, Yan Jiao, Yao Zheng, and Shi-Zhang Qiao
Abstract: Copper is a significant platform for CO2 electroreduction catalysts because it is the only known metal to produce multi-carbon products but suffers from poor selectivity. In the early stages of the reaction pathway, a selectivity-determining step dictates if the pathway leads to formate (a dead-end) or to CO (and on to multi-carbon products). Therefore, controlling the adsorption of key intermediates, in order to steer the reaction pathway as desired, is critical for selective CO2 electroreduction. Alloying copper is a strategy in which the composition and electronic properties of the alloy surface can be finely tuned to alter the reaction intermediate adsorption behavior. Herein, through in situ Raman spectroscopy and density functional theory (DFT) calculations, we investigate a composition-dependent selectivity toward CO and formate during CO2 electroreduction on a range of Cu–Sn alloy catalysts. We find that the selectivity shifts from CO to formate generation as the Sn content in the alloy catalyst increases because of a shift in adsorption preference from the C-bound *COOH intermediate to the O-bound *OCHO intermediate. Theoretical DFT calculation results indicate that this selectivity shift is due to a gradual weakening of *COOH adsorption and strengthening of *OCHO that occurs with increasing Sn content. A combination of theoretical Bader charge analysis and experimental X-ray photoelectron spectroscopy revealed the origin of such transformation: upon alloying, charge is redistributed from Sn to Cu, which creates regions of localized positive charge on the Sn sites. Therefore, with increasing tin content, these localized positive sites hinder the nucleophilic attack of the CO2 carbon, making *COOH adsorption (and the CO pathway) less favorable.
Keywords: Carbon dioxide reduction; copper alloys; selectivity control; Raman spectroscopy; density functional theory
Rights: © 2019 American Chemical Society
DOI: 10.1021/acscatal.9b02312
Grant ID: http://purl.org/au-research/grants/arc/FL170100154
http://purl.org/au-research/grants/arc/DP160104866
http://purl.org/au-research/grants/arc/DP170104464
http://purl.org/au-research/grants/arc/DE160101163
http://purl.org/au-research/grants/arc/LP160100927
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Chemical Engineering publications

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