Direct alcohol fuel cells: Toward the power densities of hydrogen-fed proton exchange membrane fuel cells

A 2m 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 (1.5mg(Pd)cm(-2)), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160mWcm(-2) at 80 degrees C were produced if the cell was fed with 10wt% aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2M aqueous KOH. The Pd loading of the anode was increased to 6mgcm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 degrees C of 335mWcm(-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 degrees C approach the output of H-2-fed proton exchange membrane fuel cells.