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Application of iron-based cathode catalysts in a microbial fuel cellBirry, L.; Mehta, P.; Jaouen, F.; Dodelet, J.-P.; Guiot, S.R.; Tartakovsky, B.Electrochimica Acta 56 (2011) [1505][1506][1507][1508][1509][1510][1511] (FePc). These materials were subsequently pyrolyzed at a high temperature. The ORR activity of all Fe-based catalysts was measured at pH 7 with a rotating disk electrode (RDE) and their performance for electricity production was then verified in a continuous flow MFC. Catalysts prepared with FeAc and pyrolyzed in NH 3 showed poor activity in RDE tests as well as a poor performance in a MFC. The ORR activity and fuel cell performance for catalysts prepared with ClFeTMPP and FePc and pyrolyzed in Ar were significantly higher and comparable for both precursors. The iron loading was optimized for FePc-based catalysts. With a constant catalyst load of 2 mg cm −2 in a MFC, the highest power output (550-590 mW/m 2 ) was observed when the Fe content was 0.5-0.8 wt%, corresponding to only 0.01-016 mg Fe/cm 2 . A similar power output was observed using a Pt-based carbon cloth cathode containing 0.5 mg Pt/cm 2 . Long-term stability of the Fe-based cathode (0.5 wt% Fe) was confirmed over 20 days of MFC testing.Crown

A method that involves stenciling electrodes using dry powders for fuel cells is described and compared to anodes and cathodes prepared by the traditional spraying method using catalyst inks. Methods to determine the proton conductivity of the DMFC anode layer are also discussed. The stenciling method allows for the preparation of highly reproducible membrane electrode assemblies (MEAs) utilizing little waste material. MEAs can be prepared in a controlled manner using the stenciling technique. The resulting morphology of the as-prepared electrodes is observed to be dependent on the preparation method, while the thickness of the once hot-pressed catalyst layers appears to be independent of the preparation method. Stenciled anodes of the same catalyst loading were found to show a lower proton resistance (R p ) than sprayed anodes. However, the lower R p value was not sufficient to result in a measurable increase in the performance of a direct methanol fuel cell (DMFC); as in fact, the average steady-state DMFC performance was found to be the same using sprayed or stenciled electrodes. The DMFC performance was found to be strongly dependent on the Nafion content and large increases in the Nafion content were needed to increase the DMFC performance measurably. Even though thick electrodes were prepared in this work, the R p values of the stenciled anodes were found to be comparable to results reported in the literature for much thinner electrodes made using high metal catalyst loadings on carbon. This observation is most probably due to the higher Nafion content used in this work.