Redox and Oxygen Evolution Electrocatalytic Properties of Nafion and Single-Walled Carbon Nanotube/Hydrous Iron Oxide Composite Films

Novel Nafion and single-walled carbon nanotube composite hydrous iron oxide electrodes have been fabricated using a simple potential cycling methodology and are examined as oxygen evolution electrocatalyst films. Hydrous oxide materials prepared in this manner are typically quite amorphous in nature. Here, we show, using scanning electron microscopy and cyclic voltammetry, that a more uniform oxide growth can be achieved using a Nafion or carbon nanotube matrix as a template. This templated growth produces oxide films with unique surface morphologies and electrical properties. In particular, the composite films exhibit superior conductivity, as shown by electrochemical impedance spectroscopy, with up to eightfold decrease in charge transfer resistance. The ultimate result is an enhancement in the electrocatalytic performance of the hydrous Fe oxide film. Steady-state polarisation studies on the oxygen evolution reaction show a reduction in overpotential of up to 50 mV for the composite electrodes with a threefold increase in turnover frequency.