One-dimensional metallic nanostructures such as nanowires, rods, and tubes have drawn much attention for electrocatalytic applications due to potential advantages that include fewer diffusion impeding interfaces with polymeric binders, more facile pathways for electron transfer, and more effective exposure of active surface sites. 1D nanostructured electrodes have been fabricated using a variety of methods, typically showing improved current response which has been attributed to improved CO tolerance, enhanced surface activity, and/or improved transport characteristics. A template wetting approach was used to fabricate an array of platinum nanotubules which were examined electrochemically with regard to the electrooxidation of formic acid. Arrays of 100 and 200？nm nanotubules were compared to a traditional platinum black catalyst, all of which were found to have similar surface areas. Peak formic acid oxidation current was observed to be highest for the 100？nm nanotubule array, followed by the 200？nm array and the Pt black; however, CO tolerance of all electrodes was similar, as were the onset potentials of the oxidation and reduction peaks. The higher current response was attributed to enhanced mass transfer in the nanotubule electrodes, likely due to a combination of both the more open nanostructure as well as the lack of a polymeric binder in the catalyst layer. 1. Introduction Nanostructured materials have long been used in catalysis, usually in the form of metallic nanoparticles on high surface area supports with nanoscale porosity. More recently, one-dimensional metallic nanostructures such as nanowires, rods, and tubes have drawn attention for such electrocatalytic applications, including fuel cells and electrochemical sensors. These types of structures present many potential advantages, including fewer diffusion impeding interfaces with polymeric binders, more facile pathways for electron transfer, and more effective exposure of active surface sites. Such 1D metallic nanostructures have been fabricated by a variety of methods, including template-based methods (wetting [1–4] and electrosynthesis or electrodeposition [5–11]), electrospinning [12], deposition onto nanowire or nanofiber supports [13–15], and others [16–19]. To date, most studies of these nanomaterials have focused on demonstrating the viability of the nanofabrication process and describing fundamental material properties such as morphology, composition, and crystal structure with far less attention paid to their functional properties. Electrocatalytic studies of 1D metal
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