Zinc oxide nanoparticles incorporated in ultrathin layer silicate films and their photocatalytic properties

This study has been conducted to determine whether the nanosized semiconductor crystals qualify as photocatalysts also in that case when they are self-assembled to form ultrathin films in the thickness range of 10–500 nm. For this purpose, multilayer films of Zn(OH)₂ and ZnO nanoparticles were prepared by the layer-by-layer self-assembly method on glass surface. A transparent layer silicate, synthetic hectorite was used as sticking material. The quality of multilayer formation has been investigated in detail by absorption spectrophotometry, XRD and atomic force microscopy (AFM). Evidence was found for the uniform deposition of the different components. The increment of nanofilm thickness was constant and independent from the number of layers deposited previously. Photocatalytic measurements were made with model organic materials β-naphtol and industrial kerosene in a home-made loop-type batch reactor. Decomposition has been continously monitored by UV spectrometry. Significant photodegradation of the organic molecules were only found in the presence of the nanofilms.