Photocatalytic synthesis of reduced graphene oxide-zinc oxide: effects of light intensity and exposure time

Abstract

A series of composites containing reduced graphene oxide and zinc oxide (rGO-ZnO) with optimum GO loading amount of 3 wt% was successfully synthesized through an in-situ photocatalytic reduction of graphene oxide (GO) over ZnO photocatalyst under UV light irradiation. Different light intensities and exposure times were confirmed to affect the properties and photocatalytic performance of the rGO-ZnO for photocatalytic degradation of phenol as an organic pollutant model. The best photocatalyst was obtained under UV light intensity of 0.4 mW cm−2 for 24 h exposure and it gave around three times higher photocatalytic performance than that of the bare ZnO. Compensating for the long exposure time, such low light intensity was crucial to generate rGO with low amount of defects. The low amount of defects resulted in low electron-hole recombination, low resistance of a charge transfer, and high electron-transfer rate constant, which in turn enhanced the photocatalytic performance. Reusability tests demonstrated the potential use of rGO-ZnO as a good photocatalyst for organic pollutant degradations.