A novel nanocomposite catalytic cathode for direct methanol fuel cells

Abstract

We report a new nanocomposite catalytic cathode composed of iron phthalocyanine, platinum, carbon black and Nafion ® (FePc-Pt/C-Nafion ®) which exhibited enhanced catalytic activity for the oxygen reduction reaction (ORR) in the presence of methanol compared with usual Pt/C based electrodes. The catalytic cathode was prepared by depositing Pt colloidal nanoparticles ( d av = 2.2 nm) on a FePc/C support to form a FePc-Pt/C powder and ultrasonically treating a mixture of Nafion ® and the FePc-Pt/C powder in ethanol, followed by loading the mixture on a glassy carbon electrode and drying at 120 °C. In an O 2-saturated H 2SO 4 solution (0.5 M) with methanol (0.5 M), the onset potential (0.92 V vs RHE) over the FePc-Pt/C-Nafion ® electrode shifted by more than 240 mV toward positive relative to that over an electrode prepared with a commercial Pt/C catalyst and Nafion ®. A new kind of catalytic sites constructed by FePc nanocrystals and Pt nanoparticles was found in the FePc-Pt/C-Nafion ® electrode for the first time, which exhibited higher specific activity for ORR than Pt as calculated based on the hydrogen desorption charge.