Preparation Parameter Development for Layer-by-Layer Assembly of Keggin-type Polyoxometalates

Abstract

Polyoxometalates possess many useful properties for electrochemical catalysis. These molecule-size clusters can be assembled into thin films through the layer-by-layer method. In this study, we determined a cluster concentration range within which layer-by-layer (LbL) films have been successfully fabricated. We also find the influence of salt added to the deposition solutions. In an attempt to understand the self-assembly process at the molecular level, thermodynamic arguments, derived from complexation between nanoscale particles and oppositely charged polyelectrolyte chains, have been employed to interpret the adsorption of polyoxometalate clusters onto a cationic polymer layer. The scaling results describe the contact mode between a polymer chain and a cluster. The assembly can be visualized with assistance by understanding the contact between the polymer chain and the cluster.

Ion Transfer in Layer-by-Layer Films

“…The high permeability may be originated from a moderate delamination of films and less-stratified microstructure. Compared to the PMo 12 surface coverage trend, 60 the diffusion of [Fe(CN) 6 ] 3-/4-couple into the multilayer assembly seems independent of the PMo 12 loading.…”

“…PMO 12 PDDA multilayer films were deposited according to our recently published procedure. 60 APTES modified ITO slides were dipped in PMO 12 solution (10 min) and PDDA solution (10 min) in an alternating fashion for 10 consecutive times, between each dipping the slides were exposed to three consecutive water baths for 5 seconds each. Electrochemical cell and the measurements.…”

“…We attempt to find a generic fabrication rule that applies to most POM clusters. 60 In the study, we used Keggin type POM clusters to study their layer-by-layer deposition behavior. We found that POMs can be adsorbed onto LbL assemblies from concentration range 0.1 to 5 mM.…”

Synthesis and Antitumoral Activity of Gelatin/Polyoxometalate Hybrid Nanoparticles

“…Being inorganic oligomeric aggregates, POMs can not only form insoluble complexes with many positive charged polymers, [18][19][20][21][22] but can also construct coacervates with zwitterionic proteins through electrostatic interactions. [20,23,24] The obtained complexes are usually not stable in solution, and will eventually precipitate out from the system in the absence of proper stabilizers or surfactants.…”

Enhanced Electrocatalysis for Methanol Oxidation on Ordered {[PdPW11O39]5–/Pt/PAMAM}n Multilayer Composites

“…It is believed that Keggin-type Polyoxometalates (POMs) in an aqueous solution could effectively assist the electrochemical oxidation of carbon monoxide (CO) to carbon dioxide (CO 2 ) [23,24]. The transition metal-substituted polyoxometalates (TMSP) have the potential wider application due to their better performance including catalytic reactivity [25], the possibility of multiple electron transfer [26], ªpseudo liquid phaseº behavior [27], and extremely versatile inorganic building blocks for the construction of organic-inorganic composites [28]. It has been observed that the electrocatalytic activities of Pt catalysts are enhanced when supported by TMSP [29,30], which suggests that it is possible for them to be employed as catalysts in the anodic methanol oxidation process.…”