▎ 摘　　要

Industrial dye waste is highly toxic, nonbiodegradable, and has a significant negative impact on the environment. Photodegradation of phenothiazine derivative dyes by undoped Fe3O4 nanoparticles (Fe3O4), reduced graphene oxide (rGO)-doped Fe3O4 nanocomposites (G@Fe3O4), nickel-doped Fe3O4 nanoparticles (Ni@Fe3O4), and graphene-nickel codoped Fe3O4 nanocomposites (Ni/G@Fe3O4) is achieved using a facile coprecipitation technique. The X-ray powder diffraction patterns of all the prepared samples confirm the face-centered cubic structure of metallic Fe3O4. The crystallite size of the Ni-doped samples increases, indicating that the addition of Ni2+ significantly increases the crystalline grain growth of Fe3O4, whereas the addition of graphene dopants results in a decrease in the particle size and an increase in the bandgap. The higher specific surface area of Ni/G@Fe3O4 (70.082 m(2) g(-1)) is attributed to the introduction of rGO nanoflakes and the formation of secondary pores. The X-ray photoelectron spectra of O 1s, C 1s, Ni 2p, and Fe 2p confirm the presence of oxygen anions, graphene, Ni2+ ions, and Fe3+ and Fe2+ oxidation states in the Fe3O4 lattice.