Preparation of Metal Oxide Nanofilms Using Graphene Oxide as a Template

Abstract

Two-dimensional (2D) materials have lately attracted significant attention, including nanosheets composed of metal oxide single crystallites that are typically prepared using a top-down synthesis method such as the exfoliation of layered metal oxides. In the present study, nanofilms composed of polycrystallites of metal oxides such as TiO2, ZrO2, Nb2O5, SnO2, and Ta2O5 were prepared from the corresponding metal alkoxides using graphene oxide (GO) as a template, applying a bottom-up method. In this process, dried GO powder was dispersed in cyclohexane containing metal alkoxides and then treated at 453 K in an autoclave, such that the GO was converted into reduced GO (rGO) and metal oxide nanofilms were deposited on the rGO. Free-standing metal oxide nanofilms were subsequently obtained by calcination of the rGO/metal oxide composites in air at temperatures above 723 K. When dried GO was dispersed in cyclohexane containing metal alkoxides, the alkoxides adsorbed on the oxygen-containing functional groups of the GO were hydrolyzed by adsorbed or intercalated water in the dried GO and/or by water generated during the reduction of the GO, to form metal oxide nanofilms on the rGO.