Electrochemical Characterisation of Platinum Nanoparticles Prepared in a Water-in-Oil Microemulsion in the Presence of Different Modifiers and Metal Precursors

Abstract

In this work, water-in-oil microemulsions are used in the presence of various modifiers and metal precursors to obtain preferentially oriented Pt nanoparticles. Preferentially oriented cubic nanoparticles, enriched in (100) sites, are prepared using specific concentrations of HCl, HBr, H2SO4 and H3PO4. By contrast, the use of citric and oxalic acids increases the amount of (111) sites, albeit not significantly. Nanoparticles are electrochemically characterised by hydrogen and Ge adsorption/desorption processes, as well as CO stripping. Finally, the electrocatalytic activity of the nanoparticles having the highest percentage of (100) sites is evaluated for ammonia oxidation, confirming the electrochemical characterisation results. The results obtained indicate that, 15 % HCl-modified Pt nanoparticles synthesised using K2PtCl4 as metal precursor displayed the highest amount of (100) sites (46.7 %), and gave the highest peak current density for ammonia oxidation, around fivefold that of polyoriented Pt.