Heat treatment of carbon-based powders carrying platinum alloy catalysts for oxygen reduction: influence on corrosion resistance and particle size

The influence of heat treatment of carbon-based powders carrying platinum and platinum-iron binary alloy catalysts for oxygen reduction is investigated. The catalysts powders are subjected to heating at various temperatures for a certain time. An accelerated ageing test (AAT) is used to evaluate the corrosion resistance and sintering resistance of each catalyst. The dissolution of the catalyst in the AAT filtrate is analysed with a spectrophotometer and provides a measure of the corrosion resistance. The particle size of catalyst powders before and after AAT is determined by X-ray diffraction and indicates the sintering resistance. Transmission electron microscopy and electron diffraction techniques are also employed as supplementary testing methods. So-called ‘anchor effects’ are proposed to explain the enhanced effect of iron in platinum-iron binary catalysts compared with catalysts that contain platinum alone.