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In situ determination of the nanostructure effects on the activity, stability and selectivity of Pt-Sn ethanol oxidation catalysts

DOI: 10.1016/j.jelechem.2017.09.060 DOI Help

Authors: Laura Calvillo (University of Southampton; University of Padova) , Lucila Méndez De Leo (Universidad de Buenos Aires) , Stephen J. Thompson (University of Southampton) , Stephen W. T. Price (University of Southampton; Diamond Light Source) , Ernesto J. Calvo (Universidad de Buenos Aires) , Andrea E. Russell (University of Southampton)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Electroanalytical Chemistry

State: Published (Approved)
Published: September 2017
Diamond Proposal Number(s): 8071

Abstract: Nanoparticle catalysts comprising two PtSn alloys with different Pt:Sn atomic ratios and a Sn modified Pt catalyst were prepared in order to study the effect of the particle nanostructures on the activity towards the ethanol electrooxidation and the selectivity to CO2. An accurate model of the electronic and structural properties, obtained by ex situ analysis, was established. Alloying of Sn with Pt causes the expansion of the lattice parameter of Pt and modifies its electronic structure. In contrast, the deposition of Sn on the Pt surface has neither effect. The activity of the catalysts towards ethanol oxidation was established voltammetrically and the CO2 selectivity via in situ Fourier transform infrared spectroscopy (FTIRS). Results indicated that the modification of the electronic environment of Pt in Pt-Sn alloys results in a weaker adsorption of the intermediates (acetaldehyde and acetic acid), which desorb easily from the surface of the catalyst resulting in incomplete oxidation to CO2. In contrast, when the electronic structure is not perturbed (Sn modified Pt sample), the amount of CO2 produced increases. The stability of the different nanostructures under working conditions was investigated by in situ X-ray absorption spectroscopy (XAS) measurements, which show that initially both the Sn modified Pt and Pt-Sn alloy nanostructures are stable under applied potential in the potential window studied and in presence of ethanol. Accelerated aging studies showed that the Sn modified Pt nanostructure remained stable, whereas a significant structural change was observed for the Pt-Sn alloys.

Journal Keywords: Pt-Sn nanostructures; Ethanol electrooxidation; In situ FTIRS; In situ XAFS; Structural stability

Subject Areas: Chemistry

Instruments: B18-Core EXAFS

Other Facilities: ALBA

Added On: 04/10/2017 09:46

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