{'fraction_non_alphanumeric': 0.04308202154101077, 'fraction_numerical': 0.019055509527754765, 'mean_word_length': 5.425531914893617, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Analysis of Reaction Kinetics for Carbon Monoxide and Carbon Dioxide on Polycrystalline Platinum Relative to Fuel Cell Operation

Polymer electrolyte fuel cells operate a high efficiencies using pure H{sub 2} fuel. H{sub 2} produced by reforming hydrocarbons or alcohols contains CO and CO{sub 2} (CO{sub x}) impurities which readily adsorb onto anode Pt electrocatalysts, reducing the efficiency for H{sub 2} electrooxidation. A CO{sub x} inventory model is useful for describing the behavior of adsorbed CO on Pt electrocatalyst surfaces. The model compares three fluxes: (1) direct adsorption of CO, (2) the electroreduction of CO{sub 2}, and (3) electrooxidation of adsorbed CO. The fluxes of CO{sub 2} electroreduction and CO electrooxidation were measured electrochemically on polycrystalline Pt electrodes (surface roughness = 30--100) in 1 N H{sub 2}SO{sub 4} between 23 and 66 C. This study concludes that, under polymer electrolyte fuel cell conditions, CO tolerance is achieved when the flux of CO electrooxidation balances the combined adsorption fluxes from both CO and CO{sub 2}. Furthermore, under most conditions, CO adsorption will generally exceed the fluxes of CO{sub 2} electroreduction.