Applied bias photon-to-current conversion efficiency of ZnO enhanced by hybridization with reduced graphene oxide

摘要

The role of reduced graphene oxide (rGO) in the enhancement of photo-conversion efficiency of ZnO films for photoelectmchemical (PEC) water-splitting applications was analyzed.ZnO and rGO-hybridized ZnO (rGO/ZnO) films were prepared via a two-step electrochemical deposition method followed by annealing at 300 ℃ under argon gas flow.The physical,optical and electrochemical properties of the films were characterized to identify the effect of rGO-hybridization on the applied bias photon-to-current efficiency (ABPE) of ZnO.Scanning electron microscopy and X-ray diffraction indicated the formation of verticallyaligned,wurtzite-phase ZnO nanorods.Diffuse-reflectance UV-visible spectroscopy indicated that rGOhybridization was able to increase the light absorption range of the rGO/ZnO film.UPS analysis showed that hybridization with rGO increased the band gap of ZnO (3.56 eV) to 3.63 eV for rGO/ZnO sample,which may be attributed to the Burstein-Moss effect.Photoluminescence (PL) spectra disclosed that rGOhybridization suppressed electron-hole recombination due to crystal defects.Linear sweep voltammetry of the prepared thin films showed photocurrent density of 1.0 and 1.8 mA/cm2 for ZnO and rGO/ZnO at +0.7 V,which corresponded to an ABPE of 0.55％ and 0.95％,respectively.Thus,this report highlighted the multi-faceted role of rGO-hybridization in the enhancement of ZnO photo-conversion efficiency.