CoFe₂O₄–Fe₃O₄bimagnetic heterostructure: a versatile core-shell nanoparticle with magnetically recoverable photocatalytic and self heating properties

Abstract

CoFe 2 O 4 -Fe 3 O 4 (Fe/Co=2.3, 2.75 & 3.5) core-shell magnetic nanocomposite (MNC) was successfully prepared by combined sonochemical and reverse co-precipitation method using cost effective and readily available precursor. The structure, morphology, thermal, optical and magnetic properties of the MNC was extensively studied and the product was found suitable for use as an environmentally safe recyclable photocatalyst for pollution control. The self-heating properties of the MNC was also investigated for magnetic hyperthermia application. The studies of Infrared (IR) and Ultraviolet-visible (UV-Vis) spectroscopy confirmed the synthesis and formation of the bimagnetic heterostructure. The x-ray Diffraction studies and Transmission Electron Microscopy (TEM) analysis confirmed the formation of subnanometer clusters(<10 nm) in the asprepared samples. The results of Differential Scanning Calorimetry (DSC)/Thermo-Gravimetric Analysis (TGA) analysis of the as prepared samples showed transformation of intermediate Fe-phases to Fe 3 O 4 during sample heating at 420°C. This transformation accompanied structural changes in the asprepared sample that led to the formation of the coreshell structure which was observed in the TEM images of the annealed sample with Fe/Co ratio (x=3.5). The magnetization-hysteresis (M-H) studies was done on the asprepared and annealed samples using the Vibrating Sample Magnetometer (VSM). The VSM studies showed significant improvement of magnetization and coercivity in the annealed samples making it suitable for re-usability in photocatalytic reaction and magnetic hyperthermia application. The degradation of phenolphthalein (a non-biodegradable organic chemical) in the presence of UV light irradiation was used as a reference reaction to confirm the photocatalytic properties of the CoFe 2 O 4 -Fe 3 O 4 MNC, which could be well isolated from the media at the end of degradation, by applying an external magnetic field and reused. The nanocomposite was also investigated for magnetic hyperthermia using induction heating properties and the result infer that it is also a promising material for hyperthermia application.

A comparative investigation of normal and inverted exchange bias effect for magnetic fluid hyperthermia applications

“…11 , the FNMNPs are proven to be nontoxic as guided by the biological evaluation for in vitro cytotoxicity test of part 5 64 , as the cell viabilities are above 70% at all different concentrations for upto 72 h respectively. However, as observed usually in biocompatibility test, reduction in the cell viability percentage is manifested with increasing the sample concentration and incubation time 37 , 39 , 65 . Therefore, based on the cytotoxicity response, FN sample is evidently nontoxic even at 1 mg/ml concentration incubated for 72 h, which marks the samples as biocompatible and thus nanocomposites of NiO and Fe 3 O 4 are suitable for magnetic fluid hyperthermia (MFH) treatment.…”

An Investigation of Inverted Core@Shell Nanostructure for Efficacious Magnetic Hyperthermia Applications

“…One of the prime methods to tune or amplify the properties of MNPs is the junction interface coupling of a CS nanostructure. [9][10][11] One of the centric properties or phenomena that is a consequence of junction interface coupling is the exchange bias effect (EBE) manifesting to reposition of the M-H loop with magnifying coercivity. [12,13] This special kind of anisotropy first arrived into the picture when Meiklejohn et al explored their interest in Co@CoO core@shell (CS) nanostructure.…”