A composite anode with reactive methanol filter for direct methanol fuel cell

Two composite electrode structures for direct methanol fuel cells comprising an outer, middle and an inner catalyst layers, are proposed to suppress methanol crossover and improve the utilization efficiency of methanol fuel. These two composite anodes have structures I and II, and are prepared by a combination of screen-printing, direct-printing and impregnation–reduction (IR) methods. The inner layer of these two composite anodes, which are prepared by IR method, is a layer of nanometer-sized Pt₃₇–Ru₆₃/Pt or Pt₃₇–Ru₆₃/Pt₂₀–Ru₈₀ catalyst particles deposited in the PEM anode side serving as the reactive methanol filter layer. The suppression of methanol crossover and the membrane electrode assembly (MEA) performance of the proposed structures are compared to those of the normal-MEA structure with PEM without IR treatment. The mechanisms of the suppression of methanol crossover are investigated. Experimental results show that the MEA-I and MEA-II improve the suppression of methanol crossover by up to 22% and 33% compared to the normal-MEA structure, respectively, and yield a 12% and 18% better MEA performance than the normal-MEA structure, respectively. The filtering and electrode effects of a layer of nanometer-sized Pt₃₇–Ru₆₃/Pt or Pt₃₇–Ru₆₃/Pt₂₀–Ru₈₀ catalyst particles deposited in the PEM anode side contribute to the suppression of methanol crossover and performance enhancement.