Electrocatalysis of CO Tolerance by Carbon-Supported PtMo Electrocatalysts in PEMFCs

Abstract

This paper is a full version of an earlier short communication, where significantly higher (up to threefold) CO tolerance was reported for PtMo/C (atomic ratio, Pt:Mo, 3:1) relative to the current state-of-the-art PtRu/C (1:1) in a proton exchange membrane fuel cell (PEMFC) under standard operating conditions (85°C, 100% humidification, with H2+100H2+100 pm CO//O2).CO//O2). We report significantly different behavior for PtMo/C in contrast to PtRu/C, wherein there is negligible variation in CO tolerance (100 ppm CO in H2)H2) with variations in alloying compositions (Pt:Mo, 1:1 to 5:1). Further, in contrast to Pt/C and PtRu/C, significantly lower variations in overpotential losses is observed for PtMo/C as a function of temperature (55–115°C) and CO concentrations (5–100 ppm, balance H2).H2). In addition, excellent long-term stability is reported for PtMo/C (1:1) under steady-state conditions (constant potential conditions at 0.6 V) for a total duration of 1500 h, with anode gas composition varied between pure H2H2 and those with 100 ppm CO, with or without the presence of other reformate gases (primarily CO2CO2 and N2).N2). These are discussed in the context of detailed physicochemical characterization of the nanoparticles using a combination of X-ray diffraction, transmission electron microscopy, and in situ synchrotron X-ray absorption spectroscopy. © 2004 The Electrochemical Society. All rights reserved.