Redox, surface and electrocatalytic properties of layer-by-layer films based upon Fe(III)-substituted crown polyoxometalate [P₈W ₄₈O₁₈₄Fe₁₆(OH)₂₈(H ₂O)₄]^20-

The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li₄K₁₆[P₈W ₄₈O₁₈₄Fe₁₆(OH)₂₈(H ₂O)₄]·66H₂O·2KCl (P ₈W₄₈Fe₁₆) towards the reduction of both nitrite and hydrogen peroxide reduction has been studied in both the solution and immobilized states for the POM. P₈W₄₈Fe₁₆ was surface immobilised onto carbon electrode surfaces through employment of the layer-by-layer technique (LBL) using pentaerythritol-based Ru(II)- metallodendrimer [RuD](PF₆)₈ as the cationic layer within the resulting films. The constructed multilayer films have been extensively studied by various electrochemical techniques and surface based techniques. Cyclic voltammetry and impedance spectroscopy have been utilized to monitor the construction of the LBL film after the deposition of each monolayer. The electrochemical behaviour of both a cationic and anionic redox probes at the LBL films has been undertaken to give indications as to the film's porosity. The elemental composition and the surface morphology of the LBL films was conifmrde through the employment of AFM, XPS and SEM.