▎ 摘　　要

In the present work, graphene oxide (GO)-ZnO bilayer composites were fabricated by depositing GO on ZnO by an anodic electrophoretic method. The composite films were then subjected to a cathodic electrochemical treatment with different GO reduction times. The as-prepared films were characterized by Xray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) to study changes in the GO structure. The evolution of the material's energy levels over time was also determined by ultraviolet-visible (UV-Vis) spectroscopy and electrochemical measurements. A series of structural transformations of GO occurred even after it had reached the maximum degree of reduction. Prolonged treatment saw the GO flakes fracture into smaller GO particles with a sharp increase in the proportion of carboxyl groups. The energy gap of GO varied and extended into the visible range with longer reduction time. The energy levels and charge carrier type also varied. Photoelectrochemical tests on the samples revealed that the 60 to 600-s reduced GO-ZnO composite films showed photoelectric conversion behavior as photoanodes. However, the sample reduced for 1800 s was not effective at light-harvesting owing to lowering of the GO conduction band below that of ZnO. The differences in performance indicated that the transformation of the laminated GO geometry to a more disordered distribution enhanced conversion efficiency.