Electrochemical control of the elution property of Prussian blue nanoparticle thin films: mechanism and applications

We found a method for controlling the elution property of a thin film of water-dispersible Prussian blue (w-PB) nanoparticles using a simple electrochemical treatment. The thin film of the w-PB nanoparticles fabricated by the spin-coating method was unstable in water and eluted easily. However, after electrochemical reduction and oxidation, the film did not elute in water. To clarify the mechanism, we investigated films using ultraviolet-visible absorption spectroscopy, X-ray photoemission spectroscopy, and atomic force microscopy. We propose herein that the change in the elution property occurs because of alkali cation exchange from Na⁺ to K⁺. We also demonstrated that this elution-control technique is effective for the fabrication of w-PB nanoparticle nanostructures such as multilayered thin films.