title: The bifurcation point of the oxygen reduction reaction on Au-Pd nanoalloys.
abstract: The oxygen reduction reaction is of major importance in energy conversion and storage. Controlling electrocatalytic activity and its selectivity remains a challenge of modern electrochemistry. Here, first principles calculations and analysis of experimental data unravel the mechanism of this reaction on Au-Pd nanoalloys in acid media. A mechanistic model is proposed from comparison of the electrocatalysis of oxygen and hydrogen peroxide reduction on different Au-Pd ensembles. A H2O production channel on contiguous Pd sites proceeding through intermediates different from H2O2 and OOH(σ) adsorbate is identified as the bifurcation point for the two reaction pathway alternatives to yield either H2O or H2O2. H2O2 is a leaving group, albeit reduction of H2O2 to H2O can occur by electrocatalytic HO-OH dissociation that is affected by the presence of adsorbed OOH(σ). Similarities and differences between electrochemical and direct synthesis from H2 + O2 reaction on Au-Pd nanoalloys are discussed.
authors.affiliation: Chemistry Department, University of Liverpool, L69 7ZD, UK. mrjikra@gmail.com and Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden.
authors.forename: Jakub
authors.initials: J
authors.lastname: Staszak-Jirkovský
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Ahlberg
authors.affiliation: Chalmers University of Technology, Department of Chemistry and Chemical Engineering, SE-412 96, Gothenburg, Sweden. itai.panas@chalmers.se.
authors.forename: Itai
authors.initials: I
authors.lastname: Panas
authors.affiliation: Chemistry Department, University of Liverpool, L69 7ZD, UK. mrjikra@gmail.com.
authors.forename: David J
authors.initials: DJ
authors.lastname: Schiffrin