Controlled Synthesis of ZrO2 Nanoparticles with Tailored Size, Morphology and Crystal Phases via Organic/Inorganic Hybrid Films

In this investigation, well defined mesoporous zirconia nanoparticles (ZrO2 NPs) with cubic, tetragonal or monoclinic pure phase were synthesized via thermal recovery (in air) from chitosan (CS)- or polyvinyl alcohol (PVA)-ZrOx hybrid films, prepared using sol-gel processing. This facile preparative method was found to lead to an almost quantitative recovery of the ZrOx content of the film in the form of ZrO2 NPs. Impacts of the thermal recovery temperature (450, 800 and 1100 degrees C) and polymer type (natural biowaste CS or synthetic PVA) used in fabricating the organic/inorganic hybrid films on bulk and surface characteristics of the recovered NPs were probed by means of X-ray diffractometry and photoelectron spectroscopy, FT-IR and Laser Raman spectroscopy, transmission electron and atomic force microscopy, and N-2 sorptiometry. Results obtained showed that the method applied facilates control over the size (6-30 nm) and shape (from loose cubes to agglomerates) of the recovered NPs and, hence, the bulk crystalline phase composition and the surface area (144-52 m(2)/g) and mesopore size (23-10 nm) and volume (0.31-0.11 cm(3)/g) of the resulting zirconias.