Silicotungstic Acid Based Carbon Supported Noble Metal Electrodes for Energy Conversion Application

Abstract

In this paper, carbon supported noble metal nanoparticles synthesized by using Keggin type polyoxometalate (POM), silicotungstic acid (STA), were effectively utilized as electrodes in an effort to improve the efficiency of electrochemical energy conversion processes related to direct methanol fuel cells. The excellent electron transfer and strong adsorption abilities of STA have been well exploited for the reduction of metal ions as well as the modification of carbon support to form Pt and Pt−Ru metal nanoparticles supported on carbon nanostructure composites (Pt/STA-C and Pt−Ru/STA-C) under microwave irradiation. Transmission electron microscopy results indicated that well-dispersed metal nanoparticles were formed on the carbon support. The electrocatalytic properties of Pt/STA-C and Pt−Ru/STA-C were analyzed by cyclic voltammetry and chronoamperometry through the methanol oxidation reaction for fuel cell applications. As compared with the commercial Pt−Ru/C (Johnson Matthey) and Pt/C and Pt−Ru/C electrocatalysts prepared by using the common hydrogen reduction method, the STA containing Pt/STA-C and Pt−Ru/STA-C synthesized by the method developed in this work exhibited lower onset potential, high activity with enhanced stability, and better tolerance toward poisoning by CO for the methanol oxidation reaction.