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.
Bibliographical noteConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) is gratefully acknowledged for financial support under Research Project BJT-2014/400117/2014-2 and for the research support (HV: grant #306151/2010-3). Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) is also acknowledged for financial support (grants #2013/07296-2 and #2013/16930-7), and scholarship (FWH: grant #2014/08030-9). GC gratefully acknowledges R. Camargo for his collaboration in the acquisition of the HR-TEM images and for useful discussion and suggestions.
- PtAu alloy
- formic acid oxidation
- microwave hydrothermal synthesis
- potential oscillators