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

A 2 μm 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 (1.5 mgPd cm−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 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg 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 3 D 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. Owed to an anode: The use of biomass‐derived alcohols in direct fuel cells is an attractive way to transform their chemical energy into electrical power. To avoid the drawbacks of carbon‐supported nanoparticle (NP) electrocatalysts, anodes consisting of Pd NPs supported on 3 D TiO2 nanotube arrays have been prepared. Fuel cells with these anodes produce power densities in direct fuel cells fed with bioalcohols that approach the level of H2‐fed proton exchange membrane fuel cells.