Microwave-Assisted Synthesis of Pt-Au Nanoparticles with Enhanced Electrocatalytic Activity for the Oxidation of Formic Acid

Electrochimica Acta Volume: 224 Pages: 56-63 Published: 2017

(A-E) SEM images of Pt (A) and Pt/Au 3/1 (B), 1/1 (C), 1/3 (D) and 1/9 (E) nanoparticles; (F-J) HR-TEM images of Pt (F) and Pt/Au 3/1 (G), 1/1 (H), 1/3 (I) and 1/9 (J) nanoparticles. The corresponding SAED patterns are shown below each of the HR-TEM images.

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Writers: Gema Cabello and Rogério A. Davoglio and Fabian W. Hartl and Jose F. Marco and Ernesto C. Pereira and Sonia R. Biaggio and Hamilton Varela and Angel Cuesta

Keywords: PtAu alloy; electrocatalysis; formic acid oxidation; microwave hydrothermal synthesis; potential oscillations

Abstract: We report the microwave-assisted hydrothermal synthesis of bimetallic Pt-Au nanoparticles with different Pt/Au mole ratio, and investigate their performance towards the electro-oxidation of formic acid. The as-synthesized Pt-Au sol was dispersed on a graphite electrode, without any binding agents, which allowed us to control the mass of alloy deposited. Pt-Au alloys showed better activity than bulk Pt and/or Pt nanoparticles towards the oxidation of formic acid, as evidenced by the decrease in the onset potential and the higher currents in the corresponding cyclic voltammograms. The higher activity is due both to atomic-ensemble effects, which lead the reaction through the so-called direct pathway with insignificant \{CO\} poisoning, and to electronic effects, which optimised the interaction between the catalyst surface and the reactive intermediate in the direct path. Further insight into the individual contributions of atomic-ensemble and electronic effects and their effect on the catalytic activity was provided by the analysis of galvanostatic potential oscillations.

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