▎ 摘　　要

Three-dimensional graphene foam (GF) with different layer numbers was synthesized by a chemical vapor deposition method. The number of GF layers was controlled by adjusting the feed gas ratio. The average number of layers was calculated by means of Raman spectra and found to be 2, 4, 6, 11 and 25 layers by changing the methane flow at 0.5 sccm, 0.6 sccm, 0.7 sccm, 1 sccm and 1.5 sccm, respectively. ZnO nanorods were grown on each sample by a hydrothermal method. The samples were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and Raman spectroscopy techniques. Photocatalytic degradation of methylene blue (MB) by GF/ZnO composites under visible light was studied. The results showed that the photocatalytic degradation of MB is related to the number of the graphene layers in the composite. In fact, it was concluded that the electronic structure of low-layer graphene indicates a higher capturing performance for photo-assisted electrons of ZnO nanorods.