Electrochemical oxygen reduction reaction by Pt nanoparticles on carbon support stabilized by polyoxometalates

The abilities of Keggin type polyoxometalate, silicotungstic acid (STA) to reduce metal ions by electron transfer and to modify carbon surface by strong adsorption have been explored for the preparation of Pt nanoparticles supported on carbon composites (20% Pt/STA-C). The prepared composites were characterized by Transmission electron microscopy (TEM and HRTEM)), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The electrocatalytic activities of the prepared nanocomposites were examined by using Cyclic voltammetry (CV) for oxygen reduction reaction which takes place at cathode in fuel cells. The prepared composite (20% Pt/STA-C) proved efficient compared to STA free 20% Pt/C, prepared by hydrogen reduction method. H2O2 intermediate formation is a serious concern as it reduces the activity of Pt sites during oxygen reduction. The composites prepared by polyoxometalate reduction method (20% Pt/STA-C) showed better reduction ability towards H2O2 compared to STA free 20% Pt/C composite and thus showed better performance as cathode electrocatalyst for fuel cells.