Testing PtRu/CNF catalysts for a high temperature polybenzimidazole-based direct ethanol fuel cell. Effect of metal content

Catalysts with high and low metal contents, Pt–Ru (1:1 molar ratio), supported on carbon nanofibres for the electro-oxidation of ethanol have been studied in a H3PO4-doped polybenzimidazole-based fuel cell, using ethanol fed as a vapour and operating in the temperature range 150–200 °C. The catalysts were synthesised using ethylene glycol as a reducing agent and were characterized by X-ray diffraction, TEM, SEM, BET area measurements and temperature-programmed reduction. The catalyst with the highest metal percentage showed the highest Ru alloy level. A similar crystallite size was obtained for both catalysts and oxide species were not detected. Both catalysts showed very high stability to the sintering processes during cyclic voltammetry studies. Moreover, both catalysts were tested in a direct ethanol fuel cell (DEFC) operating at high temperature (125–200 °C) and with low Pt loading in both electrodes (1 mg Pt cm−2). A positive effect of temperature was observed in both cases. The catalyst with 60% PtRu gave the highest activity in ethanol oxidation and the performance was good, which makes PtRu/CNF a promising candidate for use in a DEFC operating at high temperature.

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► PtRu/CNF in a DEFC operating at high temperature is reported for the first time.
► The PtRu/CNF showed a very high resistance to the agglomeration in acid media.
► 35 mW cm−2 was reached at 200 °C, ambient pressure, and 1 mg Pt cm−2 in both electrodes.
► Catalyst with the higher metal content achieved the higher Ru alloy level.