Performance of a novel non-platinum cathode catalyst for direct methanol fuel cells

Abstract

Currently, platinum is used as the cathode catalyst in direct methanol fuel cells (DMFCs). However, platinum reduces the number of active sites for the oxygen reduction reaction (ORR) due to the reaction between platinum and methanol and the strong adsorption of carbon monoxide molecules on the platinum surface, and in addition, platinum is very expensive. Hence, this study proposes cobalt phthalocyanine/carbon-tungsten oxide nanowires (W18O49) as a non-platinum catalyst for the cathode side of a DMFC. We determined the kinetic parameters of the catalyst and investigated the factors affecting the reaction. The factors involved in the examination of the significant parameters were the synthetic method, the pyrolysis temperature, the mass ratio of CoPc to carbon, the mass ratio of CoPc/C to tungsten hexachloride and the molarity of tungsten hexachloride. The optimum parameters were determined to be a pyrolysis temperature of 600°C and a mass ratio of CoPc/C:WCl6 of 1.90. These conditions produced a peak potential at 0.63Vvs. RHE, a mass activity of 1.76Agcatalyst−1 at 0.65V, an average electron transfer number of 3.9 with water as the main product, and an electron transfer number of 3.9 at 0.65V. Finally, the results showed that the non-platinum catalyst (which is less expensive than platinum) has similar characteristics to platinum. The single cell performance test showed that the power density is 9.0mWcm−2. The catalyst has comparable performance with other macrocycle catalysts with modified structures.