Direct fabrication of metal-free graphene nanohairs/polyimide heterojunction for the highly efficient photocatalytic degradation of industrial dyes

Abstract

A single-step three-dimensional graphene nanohairs/polyimide heterojunction (GPH) is fabricated using a CO2 laser-assisted method. An optimization process has been systematically carried out to obtain high-quality gra-phene nanohairs on polyimide. The obtained GPH was characterized by X-Ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photo-electron spectroscopy, and Fourier-transform infrared spectroscopy. Using the fabricated GPH as a photocatalyst, the photocatalytic degradation of three industrial dyes namely, methyl orange (MO), methylene blue (MB), and Rhodamine B (RhB), was studied under UV irradiation. The decolorization of the samples was studied by UV-vis absorbance spectrometer. Starting from 5 ppm dye solutions with GPH, the degradation efficiencies of 97 % for MO in 60 min, 98 % for RhB in 90 min, and 88 % for MB in 170 min, were achieved. Furthermore, the stability of GPH was evaluated and after five runs, the degradation efficiency of MO, RhB and MB is decreased to 85 %, 91 % and 75 % from 98 %, 97 %, and 88 %, respectively. The mechanism for the degradation of dyes using GPH was proposed. The simple and feasible fabrication of GPH with excellent photocatalytic dye degradation efficiency would create the new insight into the flexible heterostructures for degrading the industrial wastewater treatment process.