In-situ measurement of ethanol tolerance in an operating fuel cell Matt S. Naughton a , Claire E. Tornow b , Yolanda Bonita a , Huei-Ru “Molly” Jhong a , Fikile R. Brushett a , Andrew A. Gewirth b , Paul J.A. Kenis a, * a Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Matthews Ave, Urbana, IL 61801, USA b Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Matthews Ave, Urbana, IL 61801, USA article info Article history: Received 12 December 2012 Received in revised form 23 April 2013 Accepted 27 April 2013 Available online xxx Keywords: Alkaline fuel cell Gas diffusion electrodes Ag cathode Electrode characterization Reference electrode Non-Platinum catalyst abstract Ethanol is seen as an attractive option as a fuel for direct ethanol fuel cells and as a source for on-demand production of hydrogen in portable applications. While the effect of ethanol on in-situ electrode behavior has been studied previously, these efforts have mostly been limited to qualitative analysis. In alkaline fuel cells, several cathode catalysts, including Pt, Cu triazole, and Ag can be used. Here, we apply a methodology using a microfluidic fuel cell to analyze in-situ the performance of these cathodes as well as Pt anodes in the presence of ethanol and acetic acid, a common side product from ethanol oxidation. For a given concentration of ethanol (or acetic acid), the best cathode catalyst can be determined and the kinetic losses due to the presence of ethanol (or acetic acid) can be quantified. These experiments also yield information about power density losses from the presence of contaminants such as ethanol or acetic acid in an alkaline fuel cell. The methodology demonstrated in these experiments will enable in-situ screening of new cathodes with respect to contaminant tolerance and determining optimal operational conditions for alkaline ethanol fuel cells. Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Direct ethanol fuel cells are emerging as promising power sources due to the availability of bioethanol [1,2]. Ethanol is a liquid at ambient conditions, is relatively non-toxic, and has a high theoretical energy density of 8.0 kWh/kg [3,4]. Further- more, fuel cells are inherently more efficient than, for example, combustion-based power generation processes [5]. The use of carbon-based fuels in alkaline fuel cells has his- torically been limited by carbonate formation from CO 2 , which has prevented long-term operation in alkaline media [5e7]. More recently, alkaline membrane-based fuel cells have emerged to counteract the problem of carbonate formation [1,4,8,9]. Full electro-oxidation of ethanol still remains a challenge. In a fuel cell, ethanol can fully oxidize to carbon dioxide, producing 12 electrons, or partially oxidize to acetaldehyde or acetic acid, producing two or four electrons respectively along with water [4,10]. Common ethanol oxidation catalysts are based on Pt in acidic or alkaline media or Pd in alkaline media, but novel catalysts based on other metals are still being developed [11e14]. The commonly used PtRu and PtSn anode * Corresponding author. Tel.: þ1 217 265 0523; fax: þ1 217 333 5052. E-mail address: kenis@illinois.edu (P.J.A. Kenis). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 38 (2013) 8980 e8991 0360-3199/$ e see front matter Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2013.04.147