Formic Acid Electrooxidation by a Platinum Nanotubule Array Electrode

Abstract

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.

Self-Supporting Hierarchical Porous PtAg Alloy Nanotubular Aerogels as Highly Active and Durable Electrocatalysts

“…The j f1 / j f2 ratios for the PtAg NTAGs are also higher than that for the Pt black, indicating that the formation of the poisoning intermediate CO ads is more suppressed on the nanotubular aerogels, probably due to the so-called third-body effect. ,, The small fraction of surface Ag (third body) reduces the number of ensembles of adjacent Pt atoms (the adsorption sites for CO) due to geometrical hindrance, and correspondingly, the surface is less poisoned by the CO ads than the pure Pt surface. Compared with the reported data, as seen from Table S6, the PtAg NTAGs show higher activity than cataysts such as Pt nanotubes, Pt hollow nanospheres, or Pt nanocrystals, − and they are among the most active Pt containing catalysts for formic acid oxidation, benefiting from their unique hierarchical porous nanotubular network structure.…”