The influence of hydrogen sulphide contamination on platinum catalyst used in polymer electrolyte membrane fuel cells during potential cycling at 0.05–1.05 V vs RHE: An RRDE study

Abstract

The effect of H2S contamination on platinum catalyst has been investigated in terms of rotating ring disk electrode measurements (RRDE) in 0.1 M HClO4. The electrochemical surface area (ECSA) was determined by hydrogen underpotential deposition (HUPD) and CO stripping methods before and after accelerated stress tests (AST). The observed reduced losses of ECSA of the catalyst in the presence of H2S were associated to adsorbed sulphuric compounds on the catalyst surface which changed electrochemical characteristics of the materials surface. The RRDE experiments revealed that for oxygen reduction reaction (ORR) mass and specific activities were essentially decreased after AST with H2S contamination which was attributed to the interstitial defect on platinum atom sites due to adsorbed sulphuric compounds. Identical location and high resolution transmission electron microscopy (TEM) analysis have revealed only slightly different catalyst surface morphology and particle sizes before and after the AST indicating rather atomic scale deterioration of the platinum catalyst surface due to the adsorbed sulphur species.