Novel Visible Light Photocatalytic and Photoelectrochemical (PEC) Activity of Carbon-doped Zinc Oxide/Reduced Graphene Oxide: Supercritical Methanol Synthesis with Enhanced Photocorrosion Suppression

Carbon-doped zinc oxide/reduced graphene oxide (C-ZnO/rGO) was prepared by a facile one-pot supercritical methanol method. The synthesized C-ZnO/rGO nanocomposite with flower-like ZnO microrods (MRs) synergistically inherited all the advantages of carbon doping and rGO heterojunction and exhibited high photocatalytic activity for the photodegradation of methyl orange (MO) under visible light. The x-ray diffraction (XRD) results indicated that in presence of GO, a new carbon-doped phase was formed at the high temperature and pressure of supercritical methanol. The x-ray photoelectron spectroscopy (XPS) at low binding energies demonstrated that the valence band of C-ZnO-rGO is up-shifted by 0.35 +/- 0.05 eV compared to that of ZnO MRs and narrowed the band-gap down to 2.9 eV. Under visible light irradiation, C-ZnO/rGO showed photocatalytic degradation of MO that was greatly increased by 4.5-fold compared to that of pure ZnO MRs. Measuring the photoelectrochemical (PEC) performance illustrated that C-ZnO/rGO showed higher photocurrent density in UV and visible region compared with those of ZnO MRs electrode. In addition, the incorporation of graphene sheets greatly suppressed the photocorrosion and photocurrent density decay of C-ZnO/rGO to only 0.5% and 10%, compared with 27% and 70% for neat ZnO MRs, respectively. (C) 2017 Elsevier B.V. All rights reserved.