Structure-Property-Performance Relationship of Ultrathin Pd-Au Alloy Catalyst Layers for Low-Temperature Ethanol Oxidation in Alkaline Media

Joshua P. McClure, Jonathan Boltersdorf, David R. Baker, Thomas G. Farinha, Nicholas Dzuricky, Cesar Enrique Perez Villegas, Alexandre R. Rocha, Marina S. Leite

Research output: Contribution to journalReview articlepeer-review

7 Scopus citations

Abstract

Pd-containing alloys are promising materials for catalysis. Yet, the relationship of the structure-property performance strongly depends on their chemical composition, which is currently not fully resolved. Herein, we present a physical vapor deposition methodology for developing PdxAu1-x alloys with fine control over the chemical composition. We establish direct correlations between the composition and these materials' structural and electronic properties with its catalytic activity in an ethanol (EtOH) oxidation reaction. By combining X-ray diffraction (XRD) and X-ray photelectron spectroscopy (XPS) measurements, we validate that the Pd content within both bulk and surface compositions can be finely controlled in an ultrathin-film regime. Catalytic oxidation of EtOH on the PdxAu1-x electrodes presents the largest forward-sweeping current density for x = 0.73 at â135 mA cm-2, with the lowest onset potential and largest peak activity of 639 A gPd -1 observed for x = 0.58. Density functional theory (DFT) calculations and XPS measurements demonstrate that the valence band of the alloys is completely dominated by Pd particularly near the Fermi level, regardless of its chemical composition. Moreover, DFT provides key insights into the PdxAu1-x ligand effect, with relevant chemisorption activity descriptors probed for a large number of surface arrangements. These results demonstrate that alloys can outperform pure metals in catalytic processes, with fine control of the chemical composition being a powerful tuning knob for the electronic properties and, therefore, the catalytic activity of ultrathin PdxAu1-x catalysts. Our high-throughput experimental methodology, in connection with DFT calculations, provides a unique foundation for further materials' discovery, including machine-learning predictions for novel alloys, the development of Pd-alloyed membranes for the purification of reformate gases, binder-free ultrathin electrocatalysts for fuel cells, and room temperature lithography-based development of nanostructures for optically driven processes.

Original languageEnglish
Pages (from-to)24919-24932
Number of pages14
JournalACS applied materials & interfaces
Volume11
Issue number28
DOIs
StatePublished - 2 May 2019
Externally publishedYes

Keywords

  • alkaline medium
  • Au
  • band structure
  • electrocatalysis
  • ethanol oxidation
  • metal alloys
  • Pd
  • ultrathin catalyst layer

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