pH-Mediated fine-tuning of optical properties of graphene oxide membranes

We demonstrate a pH-mediated fine-tuning method for the transmittance and optical properties of graphene oxide membranes (GOMs) which are assembled at liquid/air interface starting from graphene oxide (GO) hydrosols. The transmittance of GOM continuously decreases with the increase of the pH value of the parent hydrosol. The size and surface chemistry of GO nanosheets are discussed to how to influence the transmittance of GO hydrosol and the optical properties of the resulting membrane since a size classification occurs in acidic condition and a deoxygenate reaction is initiated by basic environment. This study indicates an easy strategy for precisely adjusting the optical properties of graphene-based membrane, which is very important for developing novel optical devices. (C) 2011 Elsevier Ltd. All rights reserved.