A novel platinum-based nanocatalyst at a niobia-doped titania support for the hydrogen oxidation reaction

Abstract

The kinetics of the hydrogen oxidation reaction (HOR) was studied at Pt nanoparticles supported on niobia-doped titania (Pt/N–T). The catalyst support, with the composition of 0.05NbO2.5-δ -–0.995TiO2 (0 < δ < 1), was synthesized by a modified sol–gel procedure and characterized by the BET and X-ray diffraction (XRD) techniques. The specific surface area of the support was found to be 70 m2g-1. The XRD analysis revealed the presence of the anatase TiO2 phase in the support powder. No peaks indicating the existence of Nb-com­pounds were detected. Pt/N–T nanocatalyst was synthesized by the borohyd­ride reduction method. Transmission electron microscopy revealed a quite ho­mogenous distribution of the Pt nanoparticles over the support, with a mean particle size of about 3 nm. The electrochemical active surface area of Pt of 42±4 m2 g-1 was determined by the cyclic voltammetry technique. The kinetics of the HOR was investigated by linear sweep voltammetry at a rotating disc electrode in 0.5 mol dm-3 HClO4 solution. The determined value of the Tafel slope of 35 mV dec-1 and an exchange current density of 0.45 mA cm-2 per real surface area of the Pt are in good accordance with those already reported in the literature for the HOR at polycrystalline Pt and Pt nanocatalysts in acid solu­tions. This new catalyst exhibited better activity for the HOR in comparison with Pt nanocatalyst supported on Vulcan® XC-72R high area carbon.

Keywords

• niobia-doped titania support
• Pt nanocatalyst
• hydrogen oxidation reaction
• fuel cell