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The role of SnO2 in the bifunctional mechanism of CO oxidation at Pt‐SnO2 electrocatalysts

DOI: 10.1002/celc.202100642 DOI Help

Authors: Haoliang Huang (University of Southampton) , Edward T. C. Hayes (University of Southampton) , Diego Gianolio (Diamond Light Source) , Giannantonio Cibin (Diamond Light Source) , Fredrik S. Hage (University of Oslo) , Quentin M. Ramasse (University of Leeds) , Andrea Elizabeth Russell (University of Southampton)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemelectrochem

State: Published (Approved)
Published: June 2021
Diamond Proposal Number(s): 15151

Abstract: Pt-Sn bimetallic catalysts, especially Pt-Sn alloys, are considered highly CO-tolerant and are thus candidates for reformate derived hydrogen oxidation and for direct oxidation of fuel cell molecules. However, it remains unclear if this CO-tolerance originates from Sn in the Pt-Sn alloy or whether SnO 2 , present as a separate phase, also contributes. In this work, a carbon-supported Pt-SnO 2 was carefully synthesized to avoid the formation of Pt-Sn alloy phases. The resulting structure was analysed by scanning transmission electron microscopy (STEM) and detailed X-ray absorption spectroscopy (XAS). CO oxidation voltammograms of the Pt-SnO 2 /C and other SnO 2 -modified Pt surfaces unambiguously suggest that a bifunctional mechanism is indeed operative at such Pt-SnO 2 catalysts for stable CO oxidation at low overpotentials. The results from these studies suggest that the bifunctional mechanism can be attributed to the co-catalysis role of SnO 2 , in which the surface hydroxide of SnO 2 (Sn-OH) reacts with CO adsorbed on Pt surface (Pt-CO ads ) and regenerates via a Sn II /Sn IV reversible redox couple (-0.2–0.3 V vs. reversible hydrogen electrode).

Journal Keywords: bifunctional mechanism; CO oxidation; EXAFS; HAADF STEM

Diamond Keywords: Fuel Cells

Subject Areas: Chemistry, Energy

Instruments: B18-Core EXAFS

Added On: 25/06/2021 13:42

Discipline Tags:

Catalysis Inorganic Chemistry Physical Chemistry Energy Energy Storage Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)