Fabrication of silver nanoparticles decorated graphene- magnetic carbon nanotube with high photocatalytic efficacy

Abstract

In this work, we reported a facile method for synthesizing graphene oxide (GO)-polydopamine (DA)-Fe3O4-CNT (MCNT) core-shell 3D nanocluster composite materials decorated with silver nanoparticles (AgNPs) and its application for the catalytic reduction of textile dyes. Ag nanoparticles are loaded on DA and GO surface of GO-DA-MCNT nanocluster supporting material via in situ reduction. This GO-DA-MCNT nanocluster supporting material was obtained by hydrothermal treatment of an aqueous dispersion of GO and DA-MCNT. Where DA are coated on the surface of MCNT in tris-buffer solution which lead to the formation of DA-MCNT composite. The resultant nanocomposite catalyst was characterized by employing some state-of-the-art techniques such as transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), energy dispersive x-ray (EDX), and other common techniques like FTIR and UV-Vis spectroscopy. SEM and TEM study showed that the average size of the Fe3O4 and AgNPs particles are ~12 nm and ~3 nm respectively. XPS study of the materials confirmed the presence of AgNPs in the nanocomposite as Ag0 valence state. Dopamine coating and presence of other chemical functionalities were also characterized by XPS and FTIR spectroscopy. The immobilized AgNPs on the composite materials showed high catalytic efficacy for the reduction of a model dye, methylene blue (MB). The reduction of methylene blue was facilitated by fast adsorption behavior of GO for MB in aqueous systems. The fabricated Ag-GO-DA-MCNTs 3D nanocluster composite materials exhibited synergistic capabilities of efficient catalytic reduction efficiency along with fast reduction kinetics as tested for MB dye. The effects of pH on the adsorption and catalytic behavior was also investigated and maximum catalytic efficiency was observed at pH 6.4 for MB in the aqueous solution.