Highly efficient multifunctional graphene/chitosan/magnetite nanocomposites for photocatalytic degradation of important dye molecules

Abstract

Multifunctional chitosan/magnetite (CS/Fe₃O₄) and graphene/chitosan/magnetite (Gr/CS/Fe₃O₄) nanocomposites (NCs) were synthesized using a simple hydrothermal method. The NCs were subsequently evaluated as magnetic photocatalysts towards the photodegradation of dye molecules that are detrimental to the environment. In the present study, sphere shaped Fe₃O₄ nanoparticles (NPs) were found to uniformly decorate CS and Gr surfaces. The synthesized Fe₃O₄ NPs, CS/Fe₃O₄ and Gr/CS/Fe₃O₄ NCs were characterized by powder X-ray diffraction, Fourier-transform infrared and Raman spectroscopy, thermogravimetric analysis, UV-visible diffuse reflectance and photoluminescence spectroscopy, and field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The Gr/CS/Fe₃O₄ NCs showed 100% photocatalytic efficiency against rhodamine B (40 min), bromothymol blue (60 min), methylene blue (80 min) and methyl orange (100 min) compared to Fe₃O₄ NPs (100 min for Rh-B, 120 min for BTB, 160 min for MB and 180 min for MO) and CS/Fe₃O₄ NCs (90 min for Rh-B, 100 min for BTB, 140 min for MB and 150 min for MO). The photocatalytic irradiation efficiency of Fe₃O₄ NPs, CS/Fe₃O₄ and Gr/CS/Fe₃O₄ NCs, evaluated against visible light, was found to be significantly higher for Rh-B (100% within 40 min) compared to the other tested dyes.

Keywords: Hydrothermal synthesis; Multifunctional graphene/chitosan/magnetite nanocomposites; Photocatalytic degradation.