Novel heat-treated cobalt phthalocyanine/carbon-tungsten oxide nanowires (CoPc/C-W18O49) cathode catalyst for direct methanol fuel cell

Platinum group metal (PGM) is the common catalyst used in cathode side of Direct Methanol Fuel Cell (DMFC), however, problem arise because of the competitive reaction between methanol oxidation and oxygen reduction. Besides, using a PGM catalyst makes the DMFC expensive. Many non-platinum catalysts were developed but most of them produce hydrogen peroxide that is toxic to the cathode and membrane that reduces the performances of the fuel cell. Thus, this study proposes a novel non-platinum catalyst that produced water as main product instead of hydrogen peroxide. CoPc/C-W18O49 is prepared via pyrolysis and they demonstrate as a promising catalyst to replace PGM in acidic media. As a semiconductor metal oxide, W18O49 has interesting properties and is used as a catalyst support to enhance the reactivity of the oxygen reduction reaction. W18O49 were synthesized first through a solvo-thermal process and then mixed with CoPc/C via pyrolysis at 700 °C, and they were also synthesized in the reverse order. The catalyst was physically characterized by Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) and chemically characterized by Cyclic Voltammetry (CV) and Rotating Ring-Disc Electrode (RRDE) analysis for the oxygen reduction reaction (ORR). The results showed that the supported Nanowires (W18O49) are not transformed to WO3 after the pyrolysis process. The prepared catalyst, which is inert in the methanol environment electrolyte, has shown catalytic activity towards oxygen reduction in acidic media and has a 3.81-electron transfer, which produces water as the main product. The catalyst has comparable performance with other macrocycle catalysts with modified structures.