Preparation and characterization TiOx–Pt/C catalyst for hydrogen oxidation reaction

Abstract

The hydrogen oxidation reaction (HOR) was studied at the home made TiO_x–Pt/C nanocatalysts in 0.5 mol dm⁻³ HClO₄ at 25 °C. Pt/C catalyst was first synthesized by modified ethylene glycol method (EG) on commercially used carbon support (Vulcan XC-72). Then TiO_x–Pt/C catalyst was prepared by the polyole method followed by TiO_x post-deposition. The synthesized catalyst was characterized by XRD, TEM and EDX techniques. It was found that Pt/C catalyst nanoparticles were homogenously distributed over carbon support with the mean particle size of about 2.4 nm. The quite similar, homogenous distribution and particle size were obtained for Pt/C doped by TiO_x catalyst which was the confirmation that TiO_x post-deposition did not lead to significant growth of the Pt nanoparticles. The electrochemically active surface area of the catalyst was determined by using the cyclic voltammetry technique.

The kinetics of hydrogen oxidation was investigated by the linear sweep voltammetry technique at the rotating disc electrode (RDE). The kinetic equations used for the analysis were derived considering the reversible or irreversible nature of the kinetics of the HOR. It was found that the hydrogen oxidation reaction for an investigated catalyst proceeded as an electrochemically reversible reaction. The values determined for the kinetic parameters—Tafel slope of 28 mV dec⁻¹ and exchange current density about 0.4 mA cm⁻²_Pt are in good agreement with usually reported values for a hydrogen oxidation reaction with platinum catalysts in acid solutions.