Electrooxidation of acetals for direct hydrocarbon fuel cell applications

Some acetals (e.g., methylal, ethylal and 1,3-dioxolane) were oxidized in different supporting electrolytes and on various electrodes, including oxide-based electrodes dispersed onto carbon powder. The electrooxidation of ethylal and 1,3-dioxolane was demonstrated for the first time. The fuel that exhibited the lower overvoltage from the electrooxidation curve was deduced. Then, from an analysis of the reaction products from long-term anodic experiments, the electrode reactions were deduced. It was shown that the anodic polarization of the electrooxidation of acetals in an acid medium is lower than that of methanol. Thus, acetals seem to be better fuels for fuel cell applications than methanol. It was also shown that ethylal and 1,3-dioxolane are oxidised more easily than methylal for fuel cell applications. Volcano behaviour was obtained for the plot of direct oxidation current density vs metal radius for various single noble metal electrodes. The highest current density was obtained with the Pt-based electrode. Similar behaviour was obtained with electrodes based on noble binary platinum alloys, where the electrooxidation current density increases with the difference in metal radius in each alloy (ΔR). Thus, the alloys that give the highest |ΔR|, e.g. Pt–Ru and Pt–Sn, exhibit the best electrooxidation current density.