Synthesis of Ultrathin Films of Prussian Blue by Successive Ion Adsorption Technique

Abstract

Ultrathin films of Prussian blue (PB) were successfully prepared on substrates by the successive ion adsorption technique that consisted of alternate immersions of a substrate into solutions of Fe2+ and Fe(CN)63-. The PB films showed stable electrochemical redox and electrochromic properties.

High‐Contrast Electrochromism and Controllable Dissolution of Assembled Prussian Blue/Polymer Nanocomposites

“…In this study, the LPEI/PB contrast exceeds 77 % and appears to approach 80 % or greater. For comparison, previous descriptions of (presumably optimized) inorganic PB single films have reported contrasts of: 16 %, [25] 50 %, [36] and 57 %, [7] while electrochromic cells incorporating PB electrodes exhibit contrasts of 10 %, [8] 30 %, [9,10] and 60 %. [12] From comparison with previous reports, it appears that LPEI/PB contrast is superior because its bleached state is more transparent.…”

“…They exhibit the reversible PW«PB transition at an E 1/2 of approximately 0.15 V, a value consistent with PB electrochemistry described elsewhere, although slightly more cathodic than the 0.2 V that are typically reported. [5,6,25] The redox potential may be shifted because LPEI has replaced potassium as the counterion for the particle surface and accessible interior. In the case of LPEI/PB, reduc- …”

“…Arrow indicates increasing scan rate, which doubles (e.g.,25, 50, 100, 200, 400 mV s ±1 ) for each sequential curve. Square wave switching of LPEI/PB: Faradaic charge response to c) oxidation from ±0.2 V to 0.6 V and d) reduction from 0.6 V to ±0.2 V. Electrolyte was 0.1 M potassium hydrogen phthalate and potentials are reported versus K-type saturated calomel reference.…”

Fabrication and Electrochemical Investigation of Layer-by-Layer Deposited Titanium Phosphate/Prussian Blue Composite Films

“…When the TiPS-deposited substrate was immersed into FeCl 3 solution, Fe 3+ ions were electrostatically adsorbed on the substrate because the phosphate group of TiPS is negatively charged. During the subsequent immersion into aqueous K 4 [Fe(CN) 6 ] solution, Fe(CN) 6 4- ions interact and react with the previously adsorbed Fe 3+ ions to form PB . The negatively charged PB layer allows the adsorption of the next layer of positively charged hydrated titanium, and therefore composite films of TiPS/PB with increased thickness can be fabricated by repeating the above processes.…”

“…There are several ways to prepare PB-containing films. Electrochemical deposition of PB film on conductive substrates was studied by Neff and co-workers and is a simple way to prepare PB films on conductive substrates. − By multiple sequential adsorption of a substrate in aqueous solutions of Fe(CN) 6 3- and Fe 2+ or Fe(CN) 6 4- and Fe 3+ , ultrathin films of PB with tailored film thicknesses can be fabricated. − PB nanotubes were successfully prepared by a modification of this method when porous anodic alumina membrane was used as a template . PB film can also be prepared by methods such as dip-coating, casting from colloidal solution, and so forth. − While the above-mentioned methods generally produce single-component PB films, the film preparation methods working in a layer-by-layer (LbL) fashion predominantly make multicomponent PB films because of their alternating preparation process. − Among them, the electrostatic LbL assembly technique, which utilizes oppositely charged species for multilayer preparation, is highly attractive because of its simplicity in film preparation and ease in tailoring film composition and structures. − Multilayer films composed of PB nanoparticles with a size of ∼5 nm and poly(allylamine hydrochloride) (PAH) were prepared by the electrostatic LbL assembly technique and showed high sensitivity when used as a biosensor in detecting H 2 O 2 .…”