Polymer electrolyte fuel cells based on bimetallic carbon nitride electrocatalysts

In this work, two new bimetallic carbon nitride electrocatalysts, based on platinum and either nickel or iron, are tested in a single-cell PEMFC. The membrane electrode assembly (MEA) is prepared using the proposed electrocatalysts at the cathodic side and two different reference materials at the anode. MEA performance is extensively tested in both kinetically controlled (V > 0.9 V) and operative (V approximate to 0.65 V) regimes, with both air and pure oxygen as oxidants. Electrochemical information on the performance of cathodic electrodes is also obtained by carrying out measurements with the driven cell method. The proposed materials show very high activity in both operating regimes and, with respect to the reference electrocatalysts, exhibit a lower overpotential (similar to 40 mV) towards the ORR. Interestingly, only a lower mass of platinum is necessary to obtain the same electrical power (up to 0.61 g(Pt) kW(-1) vs. 1.1 g(Pt) kW(-1) of the reference MEA), leading to the possibility of producing cheaper MEAs. The electrochemical surface area of the proposed materials is larger than that of reference electrocatalysts. Lastly, the active sites of these bimetallic carbon nitride electrocatalysts are much less susceptible to CO poisoning. (C) 2007 Elsevier B.V. All rights reserved.