Enhanced formic acid oxidation on polycrystalline platinum modified by spontaneous deposition of gold. Fourier transform infrared spectroscopy studies

• Published in: Journal of power sources 2015-11, Vol.296, p.290-297
• Main Authors: Cappellari, Paula S., García, Gonzalo, Florez-Montaño, Jonathan, Barbero, Cesar A., Pastor, Elena, Planes, Gabriel A.
• Format: Article
• Language: English
• Subjects: Electroless; Formic acid; In-situ FTIR; PtAu
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.07.005

Formic acid and adsorbed carbon monoxide electrooxidation on polycrystalline Pt and Au-modified Pt surfaces were studied by cyclic voltammetry, lineal sweep voltammetry and in-situ Fourier transform infrared spectroscopy techniques. With this purpose, a polycrystalline Pt electrode was modified by spontaneous deposition of gold atoms, achieving a gold surface coverage (θ) in the range of 0 ≤ θ ≤ 0.47. Results indicate the existence of two main pathways during the formic acid oxidation reaction, i.e. dehydration and dehydrogenation routes. At higher potentials than 0.5 V the dehydrogenation pathway appears to be the operative at both Pt and Au electrodes. Meanwhile, the dehydration reaction is the main pathway for Pt at lower potentials than 0.5 V. It was found that reaction routes are easily tuned by Au deposition on the Pt sites responsible for the formic acid dehydration reaction, and hence for the catalytic formation of adsorbed carbon monoxide. Gold deposition on these Pt open sites produces an enhanced activity toward the HCOOH oxidation reaction. In general terms, the surface inhibition of the reaction by adsorbed intermediates (indirect pathway) is almost absent at gold-modified Pt electrodes, and therefore the direct pathway appears as the main route during the formic acid electrooxidation reaction. [Display omitted] •The Pt surface was modified by spontaneous (electroless) deposition of gold atoms.•Two reaction pathways are clearly identified for HCOOH electrooxidation on Pt and PtAu.•HCOOH oxidation on Pt surfaces prefers the indirect route (dehydration).•The direct pathway (dehydrogenation) for HCOOH oxidation is favored at PtAu electrodes.•The performance toward the HCOOH oxidation is greatly enhanced by PtAu electrodes.