Zno/NiO coated multi-walled carbon nanotubes for textile dyes degradation

Abstract

The nanocomposites of ZnO/NiO loaded Multiwalled Carbon Nanotubes (MWNTs) were successfully fabricated using co-precipitation method. The synthesized photocatalyst were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy, Diffused reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) for the determination of crystal structure, morphology, elemental composition and optical properties respectively. The photocatalytic activity of as prepared photocatalyst was determined by monitoring the degradation of methyl orange (an azo dye) under ultra-violet (280 nm) and visible (480 nm) irradiation. The Diffuse reflectance spectra (DRS) exhibits absorbance tail around 400 nm, in the near UV region. SEM analysis shows the homogenous dispersion of ZnO and NiO on the surface of MWNTs. The efficiency for Photodegradation of ZnO coated MWNTs is shown to be greater than the efficiency of pristine ZnO. When NiO was loaded on the surface of MWNTs having ZnO coated layer, the activity was further enhanced and reached maximum for 3% NiO loading. The degradation in visible region is believed to be proceeding through self-sensitized degradation of pre-adsorbed dye. A different behavior for degradation was observed for ZnO coated MWNTs and ZnO/NiO coated MWNTs, which suggests that complete mineralization of azo dyes can be achieved in a self-sensitized degradation process after employing ZnO/NiO coated MWNTs.