Novel Method for Deposition of Gold−Prussian Blue Nanocomposite Films Induced by Electrochemically Formed Gold Nanoparticles: Characterization and Application to Electrocatalysis

In this work, we report for the first time a one-step electrochemical deposition of gold−Prussian blue (PB) nanocomposite films. The catalytic activity of gold nuclei toward the decomposition of ferricyanide to free ferric ions and controlled generation of gold nanoparticles from HAuCl 4 solutions during potential cycling are exploited to form these nanocomposites. Concomitant electrochemical formation of both PB and gold phases leads to a “perfect blend”, in which each phase controls the growth of the other. The mechanism of formation and the features that distinguish this approach from others are highlighted. The nanocomposite films were characterized using voltammetry and UV−vis spectroscopy, field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). Interestingly, reversibility of the redox conversions of PB is enhanced by the presence of Au nanoparticles, as indicated by the reduced Δ E p value in cyclic voltammetry and low charge-transfer resistance in ac impedance spectroscopy. The nanocomposite (Au−PB) nano shows dramatically high catalytic activity toward electroreduction of hydrogen peroxide relative to that of PB on polycrystalline gold electrodes. Nanomolar detection of hydrogen peroxide is found to be feasible using these films at low cathodic potentials, which might be exploited to develop a new type of enzymeless biosensor.