Effect of dispersion methods of an unsupported Pt-Ru black anode catalyst on the power performance of a direct methanol fuel cell

The effect of the dispersion methods for an unsupported Pt-Ru (1:1) black anode catalyst on the power performance of a direct methanol fuel cell has been studied. The anode catalyst inks were fabricated by ultrasonicating or ball-milling the catalyst in two different types of dispersion solvent, namely deionized water (DI) and isopropyl alcohol (IPA). To fabricate an anode, the inks were sprayed onto the gas diffusion backing electrode, consisting of microporous layer (MPL) and carbon paper. Scanning electron microscopy (SEM) of the cross-sectional morphology of the anode catalyst layers revealed that the layers fabricated by ultrasonicating the catalyst in DI or IPA, ball-milling in DI and ball-milling in IPA consisted of granular-shaped, granular + flake-shaped and flake-shaped agglomerates, respectively. The anode catalyst layer fabricated by ball-milling in IPA exhibited the most porous structure and correspondingly represented the best power performance of 0.13 W cm−2 (0.45 A cm−2, 0.3 V) at 90 °C with 1 M aqueous methanol and atmospheric air. Control of the morphology and porosity in the catalyst layer by means of the catalyst dispersion method is suggested.