Partic. vol. 15 pp. 45-50 (August 2014)
doi: 10.1016/j.partic.2012.12.007

Effect of thermal treatment on structural change of anode electrocatalysts for direct methanol fuel cells

Mingjia Han, Jianhuang Zeng^*, Jianwei Xia, Shijun Liao

cejhzeng@scut.edu.cn

Abstract

Commercially available carbon-supported Pt, PtCo and PtRu catalysts from E-TEK are heat-treated in turn at 600 °C and 800 °C each for an hour. The as-received and as-heated catalysts are used as anode catalysts for direct methanol fuel cells. Structural and surface composition changes induced by heating are analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. For the Pt catalyst, heating the catalysts caused only the mass activity decrease due to particle sintering, whereas the specific activity and CO tolerance remained unchanged. The performance of the PtCo and PtRu catalysts is affected differently by heating. Heating the PtRu catalyst adversely affects its catalytic activity and its CO tolerance due to Pt depletion at the surface. In contrast, although Pt depletion also takes place for the heated PtCo catalysts, these catalysts show an even higher specific activity and approximately the same CO tolerance. The observed difference is likely due to the optimum atomic ratio difference for Ru/Pt and Co/Pt; an increased atomic ratio on the surface for Co/Pt results in an activity enhancement, which is contrary to the effect of the increase of Ru/Pt atomic ratio.

Graphical abstract

Keywords

Structural changes; Methanol electrooxidation; CO tolerance; Pt depletion