In-situ measurement of ethanol tolerance in an operating fuel cell

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. •Ag cathode insensitive to ethanol up to 5 M.•Ag outperforms Pt at [EtOH] ≥ 0.5 M.•Increased ethanol to oxygen molar ratio reduces tolerance.•Cu triazole performance intermediate between Ag and Pt.•Acetic acid mainly limits anode performance.