Physical properties of zinc oxide thin films coated by reduced graphene oxide for enhanced photoelectrochemical activity

Abstract

The present paper highlights the investigation of some physical properties of Zinc oxide coated by reduced graphene oxide (ZnO/rGO) grown on Tin doped indium oxide (ITO) substrates through Sol-gel process. The deposited films crystallize in the hexagonal wurtzite structure with the preferential orientation (002). Raman spectra confirm the chemical reduction of graphene oxide to rGO and the hexagonal wurtzite phase structure of the thin films. The morphological characterization indicates the good surface homogeneity, of the films. Also, it shows the significant impact of introducing rGO on the rugosity of the samples. Transmittance spectra depict a red-shift of the absorption edges with a decrease in the band gap for ZnO/rGO thin films. Electrochemical impedance spectroscopy measurements show a remarkable decrease in the charge transfer resistance from 1001 to 24.45 kΩ. In addition, ZnO/rGO photoanode has shown a remarkably enhanced current density (0.174 mA.cm−2), which is around 3 times higher than that of ZnO photoanode (0.058 mA.cm−2).