Nucleation and growth of polyoxometalate nanoparticles in polyelectrolyte multilayer films

Abstract

An effective approach to the nucleation and growth of nanoparticles was performed for forming polyoxometalate based nanoparticles: TBAB3–PMo12 (TBAB = tetrabutylammonium bromide, PMo12 = 12-molybdophosphoric anions) in multilayer films. The polyelectrolyte matrix was constructed by layer-by-layer self-assembly technology. The nucleation and growth of PMo12 nanoparticles was achieved by alternately dipping the precursor films into PMo12 and TBAB solutions, in which TBAB was employed as precipitator. Repeating the above process of absorption and precipitation of PMo12 anions, the PMo12 nanoparticles were of controllable synthesis in the multilayer films. The variation of the size and morphology of PMo12 nanoparticles was accomplished by increasing adsorption and precipitation cycle number, which was detected by transmission electron microscopy and scanning electron microscopy. The growth process, composition, and surface topography of the multilayer films containing PMo12 nanoparticles were investigated by UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The electrochemical properties were studied through cyclic voltammograms when the substrate was indium–tin oxide and the films presented good stability and similar electrochemical behavior to that of PMo12 in aqueous solution.