Functional electrochemically-active ultra-thin Nafion films

Two methods for adding electrochemical functionality to ultra-thin Nafion films are described. First, a novel "one-step procedure" to incorporate cationic redox mediators such as methyltrimethylammonioferrocene (FA⁺), within ultra-thin Nafion films is proposed. Ultra-thin films of Nafion containing FA⁺, were prepared on indium tin oxide (ITO) electrodes using the Langmuir-Schaefer (LS) technique. The morphology and thickness of the films were evaluated with atomic force microscopy (AFM). Film thicknesses were 1.9 ± 0.3 nm per LS layer and voltammetric data confirmed the successful incorporation of the mediator into the films. Key parameters such as surface coverage, concentration of the mediator within the films and apparent diffusion coefficients were extracted. Second, Pd nanoparticles were formed within Nafion LS films by loading pristine films with Pd²⁺ and then reducing the ions to form Pd. The catalytic properties of this novel nanocomposite for hydrogen oxidation were examined using cyclic voltammetry.