Preparation and electrocatalytic applications of a multilayer nanocomposite consisting of phosphomolybdate and poly(amidoamine)

Deposition of alternating layers of phosphomolybdic acid, PMo12, and genera tion-4 polyamidoamine dendrimer, PAMAM, on a gold electrode is demonstrated . The gold is first coated with a self-assembled monolayer of 4-aminothioph enol. Based on the charge under cyclic voltammetric peaks, at least 12 laye rs of PMo12 are deposited with an estimated quantity of 5.2 x 10(-11) mol c m(-2) in each. The voltammetry of PMo12 is consistent with that for solutio n studies, in that three two-electron processes are observed with formal po tentials of 0.381, 0.238 and 0.012 V. However, the dependence of peak curre nt on scan rate is indicative of redox surface-confined species. The PAMAM provided a spacer that led to a multilayer assembly with high conductivity and, because of its size, apparently high permeability. Regarding the latte r, efficient catalysis of the reduction of nitrite and the oxidation of ars enite is achieved. (C) 2001 Elsevier Science Ltd. All rights reserved.