Facile fabrication of MgAl₂O₄/MWCNT nanocomposite for efficient and stable solar-driven degradation of organic dye

Abstract

This work reports the synthesis and characterization of Magnesium Aluminate (MgAl2O4) and Magnesium Aluminate/Multi Walled Carbon Nanotube (MgAl2O4/MWCNT) nanocomposites by facile chemical co-precipitation method for the dye degradation application. MgAl2O4 and MgAl2O4/MWCNT nanocomposite are characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometery (XRD), Raman spectrometry, UV-Vis Spectrophotometery (UV-Vis), Fourier Transform Infrared Spectrometry (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Surface morphology of MgAl2O4/MWCNT nanocomposite exhibits entangled needle like structures while MgAl2O4 spinel comprises of agglomerated nanoparticles of different sizes. XRD confirms the formation of MgAl2O4. XPS identifies the chemical states and binding energies of constituent elements present in the sample. Optical properties reveal that addition of MWCNTs in MgAl2O4 decreases the optical bandgap energy from 3.02 eV to 2.78 eV. MgAl2O4/MWCNT nanocomposite shows reduced bandgap compared to pristine MgAl2O4 due to increased chemical defects or vacancies in intergranular regions and chemical interaction between MgAl2O4 and MWCNT, leading to formation of new energy levels in MgAl2O4/MWCNT nanocomposite. The addition of MWCNTs provides large surface area, more active sites, and enhances electrons mobility between energy levels. MgAl2O4/MWCNT nanocomposite proves itself a better photocatalyst due to fast degradation of Methyl Blue (MB) in 65 min as compared to MgAl2O4 which degrades the dye in 90 minutes. MgAl2O4/MWCNT nanocomposite also shows good stability and reusability even after performing the six cycles of dye degradation.