Direct Alcohol Fuel Cells: Toward the Power Densities of Hydrogen-Fed Proton Exchange Membrane Fuel Cells

A 2 ?m thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5mgPdcm-2), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm-2 at 80 °C were produced if the cell was fed with 10 wt% aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2M aqueous KOH. The Pd loading of the anode was increased to 6mg cm-2 by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm-2. Such high power densities result from a combination of the open 3D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2-fed proton exchange membrane fuel cells.