TiC, TiCN, and TiN Supported Pt Electrocatalysts for CO and Methanol Oxidation in Acidic and Alkaline Media

Abstract

TiC, TiCN, and TiN supported Pt nanoparticles have been investigated as anode electrocatalytic materials for direct methanol fuel cells. The catalysts were studied in acidic and alkaline media and compared with platinum supported on carbon black. CO and methanol oxidation were studied by voltammetry and chronoamperometry techniques. Transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction analysis were employed to characterize the novel catalysts. Results show that a carbon-supported Pt catalyst is mainly formed by nanoparticles with long (111) domains, and those catalysts with a titanium-based support present a huge amount of defect sites with diverse symmetries. Additionally to geometric factors, an electronic effect by the Ti-based support leads to considerably enhanced CO electrooxidation with respect to carbon-supported catalysts, which is of special relevance in alkaline media. However, no such improvement is observed during the methanol oxidation reaction on Ti-based catalysts at high pH.