Enhanced gas barrier properties of graphene-TiO2 nanocomposites on plastic substrates assisted by UV photoreduction of graphene oxide

Abstract

Reduced graphene oxide (rGO) sheets have received great attention as a key element for thin barrier films that block the permeation of water vapor and other gases. However, it remains a challenge to prepare the rGO-based barrier films on plastic substrates through a chemically benign and low temperature fabrication route. Toxic chemicals or high temperature thermal treatments that are widely used for preparing rGO need to be avoided because they can damage the underlying plastic substrates. In this study, we report the fabrication of rGO/TiO2 composite films via an eco-friendly and low temperature ultraviolet (UV) photoreduction process and demonstrate their enhanced gas barrier properties by measuring water vapor transmission rates (WVTRs). When photocatalytic TiO2 nanoparticles are employed, UV exposure reduces the GO/TiO2 composite solution to form rGO/TiO2, which is subsequently deposited on plastic substrates. The rGO/TiO2 composites become resistant to water absorption because the UV photoreduction of GO/TiO2 effectively removes most polar groups on the GO sheets. We confirmed that rGO/TiO2 composites were successfully deposited onto the plastic substrate through a solution process and the barrier films led to a substantial reduction in WVTRs of the substrate. Our strategy for preparing graphene-based thin barrier films by using a UV photoreduction process enables the fabrication of solution-processed graphene-based encapsulation layers on plastic substrates with an eco-friendly and low temperature fabrication method.