Effects of Platinum Loading on PEFC Power Generation Performance Deterioration by Carbon Monoxide in Hydrogen Fuel

Abstract

Hydrogen for fuel cell vehicles is likely to contain impurities from its production process, and such impurities may poison the fuel cell catalyst, which in turn will deteriorate the power generation performance of the fuel cell especially when the Pt loading is reduced. Effects of anode Pt loading and CO as an impurity on power generation performance were investigated. The test results indicated that the smaller the Pt loading in the anode was, the more rapidly cell voltage declined under the influence of CO contained in the hydrogen. The amount of voltage decrease accelerated as the Pt loading was reduced. With regard to CO and CO 2 concentrations in exhaust gas, it was found that when the cell voltage fell and stabilized following the supply of a CO-added hydrogen, a reduction of Pt loading resulted in the lowering of CO concentration and the heightening of CO 2 concentration.

Hydrogen Oxidation Artifact During Platinum Oxide Reduction in Cyclic Voltammetry Analysis of Low-Loaded PEMFC Electrodes

“…Platinum loadings of 50 μg/cm 2 are already often considered state-of-the-art, with even lower (ultra-low) loadings forecasted for the near future. Although the majority of studies in literature focuses on the cathode electrode including higher catalyst loadings and its decay during accelerated stress tests (ASTs), the anode electrode is of interest especially when investigating the effect of startup/shutdown cycles [24] or impurities [25,26] on the anode compartment, or the cell reversal tolerance upon freeze start-ups and successional reversal effects [27,28]. Therefore, thorough understanding of CVs of low-and ultra-low-loaded electrodes is of great interest.…”

Tolerance and Recovery of Ultralow-Loaded Platinum Anode Electrodes upon Carbon Monoxide and Hydrogen Sulfide Exposure

“…Generally, lower anodic catalyst loadings are less tolerant toward catalyst contaminants, as both fuel and contaminants compete for fewer active sites in the electrode. For pure Pt electrodes, the voltage drop was found to increase by 25% when the Pt-loading decreased from 400 to 50 µg/cm 2 if 1 ppm CO was introduced [12,13]. A similar trend was observed for H 2 S, where the tolerance of the electrode was found to decreased proportionally with the reduction in the anode loading [14].…”

“…In principle, the test station was comparable to the one used by Hashimasa et al [12], but with a different humidification system for the anode, a different position of the test gas feed inlet (here, the test gases were not fed through the humidifier), and no gas analysis system. In the present study, a differential cell (Baltic qCF type with automotive linear-channel flow field) with an active area of 20.25 cm 2 was employed, which allowed for the minimization of in-plane effects such as gradients in partial gas pressures, relative humidity, and temperature and therefore enhanced focus on the contamination effect at a given concentration.…”

“…The MEAs were characterized, including cyclic voltammetry (CV) on the anode and cathode side at the beginning and end of life (BOL and EOL), as were the polarization curves at the BOL, to compare the performance between the MEA types before starting the contaminant test. The gas pressure during contamination was selected in reference to the studies by Hashimasa et al [12,14], while the pressure during the polarization curves was chosen according to in-house standardized testing protocols. The conditions during the polarization curves are shown in Table 3.…”

“…The study presented here therefore seeks to add to the studies by Hashimasa et al [12,14] by investigating the tolerance of ultralow-loaded anodic platinum catalyst layers. Two different types of contaminants were selected: CO, as its poisoning effect is fully reversible, while in contrast, H 2 S typically poisons the catalyst irreversibly during regular fuel cell operation.…”