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Fishler Y, Leick N, Teeter G, Holewinski A, Smith WA. Layered Sn-Au Thin Films for Increased Electrochemical ATR-SEIRAS Enhancement. ACS Appl Mater Interfaces 2024; 16:19780-19791. [PMID: 38584348 DOI: 10.1021/acsami.4c01525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Operando electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (EC ATR-SEIRAS) is a valuable method for a fundamental understanding of electrochemical interfaces under real operating conditions. The applicability of this method depends on the ability to tune the optical and catalytic properties of an electrode film, and it thus requires unique optimization for any given material. Motivated by the growing interest in Sn-based electrocatalysts for selective reduction of CO2 to formate species, we investigate several Sn thin-film synthesis routes for the resulting SEIRA signal response. We compare the SEIRA performance of thermally evaporated metallic Sn to a series of Sn-based films on top of a SEIRA-active Au substrate (metallic Sn, oxide-derived metallic Sn, and metal oxide SnOx). Using alkanethiol self-assembled monolayers as a probe, we find that electrodepositing metallic catalyst films on top of SEIRA-active Au substrates yield higher signal relative to thermal evaporation as well as higher signal than the independent SEIRA-active Au underlayer. These observations come despite the fact that thermally evaporated Sn has a significantly higher surface roughness (and thus higher adsorbate population), suggesting specific SEIRA-magnifying effects for the stacked films. Finally, we applied these films to observe the electrochemical conversion of CO2. Differences are observed in spectral features based on the composition of the electrode being either metallic or oxide-derived metallic Sn, implying differences in their respective reaction pathways.
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Affiliation(s)
- Yuval Fishler
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80303, United States
- Renewable and Sustainable Energy Institute University of Colorado, Boulder, Colorado 80303, United States
- Materials, Chemical, and Computational Science (MCCS) Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Noemi Leick
- Materials, Chemical, and Computational Science (MCCS) Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Glenn Teeter
- Materials, Chemical, and Computational Science (MCCS) Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Adam Holewinski
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80303, United States
- Renewable and Sustainable Energy Institute University of Colorado, Boulder, Colorado 80303, United States
| | - Wilson A Smith
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80303, United States
- Renewable and Sustainable Energy Institute University of Colorado, Boulder, Colorado 80303, United States
- Materials, Chemical, and Computational Science (MCCS) Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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Hsu J, Houache MSE, Abu-Lebdeh Y, Patton RA, Guzman MI, Al-Abadleh HA. In Situ Electrochemistry of Formate on Cu Thin Films Using ATR-FTIR Spectroscopy and X-ray Photoelectron Spectroscopy. Langmuir 2024; 40:2377-2384. [PMID: 38233221 DOI: 10.1021/acs.langmuir.3c03660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Formate (HCOO-) is the most dominant intermediate identified during carbon dioxide electrochemical reduction (CO2ER). While previous studies showed that copper (Cu)-based materials that include Cu(0), Cu2O, and CuO are ideal catalysts for CO2ER, challenges to scalability stem from low selectivity and undesirable products in the -1.0-1.0 V range. There are few studies on the binding mechanism of intermediates and products for these systems as well as on changes to surface sites upon applying potential. Here, we use an in situ approach to study the redox surface chemistry of formate on Cu thin films deposited on Si wafers using a VeeMAX III spectroelectrochemical (SEC) cell compatible with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Spectra for surface species were collected in real time as a function of applied potential during cyclic voltammetry (CV) experiments. Results showed the reproducibility of CV curves on freshly prepared Cu/Si wafers with relatively high signal-to-noise ATR-FTIR absorbance features of surface species during these electrochemical experiments. The oxidation reaction of HCOO- to bicarbonate (HCO3-) was observed using ATR-FTIR at a voltage of 0.27 V. Samples were then subjected to reduction in the CV, and the aqueous phase products below the detection limit of the SEC-ATR-FTIR were identified using ion chromatography (IC). We report the formation of glycolate (H3C2O3-) and glyoxylate (HC2O3-) with trace amounts of oxalate (C2O42-), indicating that C-C coupling reactions proceed in these systems. Changes to the oxidation state of surface Cu were measured using X-ray photoelectron spectroscopy, which showed a reduction in Cu(0) and an increase in Cu(OH)2, indicating surface oxidation.
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Affiliation(s)
- Jason Hsu
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada K1A 0R6
| | - Mohamed S E Houache
- National Research Council of Canada, Energy, Mining and Environment Ottawa, Ontario, Canada K1A 0R6
| | - Yaser Abu-Lebdeh
- National Research Council of Canada, Energy, Mining and Environment Ottawa, Ontario, Canada K1A 0R6
| | - Reagan A Patton
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Marcelo I Guzman
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Hind A Al-Abadleh
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada K1A 0R6
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