Photochemical synthesis of Prussian blue film from an acidic ferricyanide solution and application

We describe a novel photochemical method to synthesize compacted Prussian blue (PB) film from an acidic ferricyanide solution. The key step is the photochemical reduction of ferricyanide ion to ferrocyanide ion that subsequently coordinates with the free ferric ion dissociated from the ferricyanide in acidic medium to form Prussian blue on the illuminated electrode surface. The prepared PB film electrode shows high electrocatalytic activity towards the reduction of hydrogen peroxide and the amperometric responses show a linear dependence on the concentration of hydrogen peroxide in a range of 1.0 × 10⁻⁶ to 1.2 × 10⁻³ M with a detection limit down to 4 × 10⁻⁷ M. The present photochemical method provides a simple and promising route for the local fabrication of patterned molecular magnets, ion-selective sensors, and electro- or photochromic devices.