Controlled Colloidal Synthesis and Basic Electrochemical Properties of TiO2-Supported Pt

Abstract

TiO2 was synthesized by forced hydrolysis process in order to be used as the support for Pt electrocatalyst (Pt/TiO2). Pt was deposited from Pt colloid solution synthesized by microwave-assisted polyol process. TiO2 powder (or C) was dispersed into H2O and 2 M H2SO4. The obtained suspension was stirred and Pt colloid was added afterwards. Upon filtration and rinsing with water, the obtained Pt/TiO2 (or Pt/C) catalyst was thermally treated at 160 C in N2 atmosphere. The catalyst water suspension for the preparation of 0.31 mg/cm2 thin layer electrode was loaded onto glassy carbon disk. Physical and chemical properties of the TiO2 and supported Pt catalyst were characterized by EDS, SEM, dynamic light scattering and XRD techniques. The influence of TiO2 thermal treatment on the electrochemical properties of Pt/TiO2 was also checked. Nominal Pt loading was 20 wt. %. EDS method revealed 18 wt. % loading of Pt on TiO2. The electrochemical properties of the Pt/TiO2 were examined by cyclic voltammetry in 0.1 M HClO4. The obtained results were compared with those obtained for carbon-supported Pt under the same conditions (Figure 1). The charge corresponding to the hydrogen desorption on Pt/TiO2 is lower than expected for 20 wt. % Pt. Although the voltammetric response is typical for Pt-based electrode material, the charge corresponds only to ~3 wt. % Pt. SEM images showed that TiO2 particles tend to form 3μm-sized agglomerates of ellipsoidal shape. The results indicate the possibility for platinum particles to be trapped inside TiO2 agglomerates. Even though calcination of TiO2 improved the Pt uptake from colloidal dispersion, it is still not as effective as commercial carbon support.