Operando X-ray absorption spectroscopic flow cell for electrochemical CO2 reduction: new insight into the role of copper species

Matam, Santhosh K., Sharma, Preetam Kumar, Yu, Eileen H., Drivas, Charalampos, Khan, Mohammad Danish, Wilding, M., Ramanan, Nitya, Gianolio, Diego, Isaacs, Mark Andrew, Guan, Shaoliang, Davies, Philip Rosser ORCID: https://orcid.org/0000-0003-4394-766X and Catlow, C. Richard A. ORCID: https://orcid.org/0000-0002-1341-1541 2024. Operando X-ray absorption spectroscopic flow cell for electrochemical CO2 reduction: new insight into the role of copper species. Catalysis Science & Technology 10.1039/D4CY00602J

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Abstract

We present a novel operando X-ray absorption spectroscopic (XAS) flow cell, consisting of a gas chamber for CO2 and a liquid chamber for the electrolyte, to monitor electrochemical CO2 reduction (eCO2R) over a gas diffusion electrode (GDE). The feasibility of the flow cell is demonstrated by collecting XAS data (during eCO2R over Cu-GDE) in a transmission mode at the Cu K-edge. The dynamic behaviour of copper during eCO2R is captured by XAS which is complemented by quasi in situ Raman and X-ray photoelectron spectroscopy (XPS). The linear combination analyses (LCA) of X-ray absorption near edge structure (XANES) indicate that copper oxides are the only species present during the first 20 min of eCO2R, corroborated by complementary Raman and XPS. Significantly, the complementary spectroscopic data suggests that the copper composition in the bulk and on the surface Cu-GDE evolve differently at and above 30 min of eCO2R. LCA indicates that at 60 min, 77% of copper occurs as metallic Cu and the remainder 23% in Cu (II) oxidation state, which is not evident from XPS that shows 100% of copper in < 2+ oxidation state. Thus, the Cu (II) is probably in the bulk of Cu-GDE, as also evident from Raman. The ethylene formation correlates very well with the occurrence of copper oxides and hydroxide species in Cu-GDE. The results not only demonstrate the applicability and versatility of the operando XAS GDE flow cell, but also illustrate the unique advantages of combining XAS with complementary Raman and XPS that enables the monitoring of the catalyst structural evolution from the bulk to surface and surface adsorbed species.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	Royal Society of Chemistry
ISSN:	2044-4753
Funders:	EPSRC
Date of First Compliant Deposit:	3 January 2025
Date of Acceptance:	30 November 2024
Last Modified:	07 Jan 2025 14:00
URI:	https://orca.cardiff.ac.uk/id/eprint/174963

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