Electrically Controlled Photocatalytic Reduction of Graphene Oxide Sheets by ZnO Nanostructures, Suitable for Tunable Optoelectronic Applications

Abstract

In this paper, a fully controlled photocatalytic reduction of graphene oxide (GO) sheets is presented in which electrical bias is applied in combination with UV illumination. It is proved that this controllability allows higher conductivities and lower UV illumination times for the achieved reduced graphene oxide (rGO) sheets, which are not allowed without gate voltage. We attribute the observed enhancement mechanism in photocatalytic reduction to electron accumulation at the ZnO/GO interface and decrement of recombination of photogenerated carriers. Then, we applied ZnO nanowires to reduce the GO sheets locally and realize rGO ribbons. The optoelectric response of the fabricated photodetector based on the realized rGO ribbon shows that by controlling the photocatalytic reduction, we can achieve a tunable/selective photodetector ( $\lambda _{\mathrm {incident}} = 520$ , 595, and 633 nm have been investigated). These functionalities allow tuning the output sensitivity of the device in response to different incident wavelengths along the fabrication process or even after the fabrication process. We believe that the presented approach introduces a new generation of tunable devices suitable for different application fields, including optoelectronics.