Highly stable MWCNT-CoFe2O4 photocatalyst. EGA-FTIR coupling as efficient tool to illustrate the formation mechanism

Abstract

MWCNT-CoFe2O4 nanocomposites were prepared in sequential synthesis steps by decorating CoFe2O4 nanoparticles on the surface of functionalized MWCNT. Initially, the CoFe2O4 nanoparticles were obtained by chemical precipitation and subsequently, the obtained CoFe2O4 nanoparticles were anchored on functionalized MWCNT through polymer wrapping. The thermal analysis approaches namely, evolved gas analysis (EGA) coupled with FT-IR spectra were involved in highlighting the sequential steps mechanism for obtaining MWCNT-CoFe2O4 nanocomposites. The composite formation was proved by X-ray Diffraction (XRD), Scanning Transmission Electron Microscopy (STEM), FT-IR spectroscopy, X-ray Photoelectron Spectroscopy (XPS). The influence of CoFe2O4 content on the magnetic and textural properties (surface area and porosity measurements) of the obtained nanocomposites was evidenced. Depicting the importance of thermal stability of nanomaterials in different industrial applications, the thermal behavior of MWCNT and CoFe2O4 was pointed out. Furthermore, the photocatalytic activity against organic pollutants such as Rhodamine B (RhB) and oxytetracicline (OTC) were evidenced. Additionally, it was evidenced that the MWCNTs acquired ferromagnetic behavior through spin polarized electron transfer from the CoFe2O4. The electron spin resonance spectroscopy (ESR) coupled with spin trapping technique was used to evidence the generation of reactive oxygen species (ROS). The obtained results suggest the efficient anchoring of CoFe2O4 on MWCNT through polymer linkage resulting in a thermal stable magnetic recoverable photocatalyst. The photocatalytic mechanism was discussed in terms spin polarized transitions and ROS generation. During the irradiation superoxide anion (O2-), hydroxyl (•OH) radical and nitroxide were detected.