Coexistence of Interfacial Stress and Charge Transfer in Graphene Oxide based Magnetic Nanocomposites

TL;DR

This study demonstrates the coexistence of interfacial stress and charge transfer in cobalt ferrite-graphene oxide nanocomposites, revealing their effects on structural, magnetic, and optical properties through various characterization techniques.

Contribution

It provides new insights into the simultaneous presence of stress and charge transfer in CoFe2O4/GO nanocomposites and quantifies their effects on material properties.

Findings

Interfacial compressive stress causes a blue shift in the G peak.

Charge transfer results in Fermi level shifts and increased FWHM of Raman peaks.

Nanocomposites exhibit confirmed magnetic and polycrystalline properties.

Abstract

In this paper, we establish the existence of both compressive stress and charge transfer process in hydrothermally synthesized cobalt ferrite-graphene oxide (CoFe2O4/GO) nanocomposites. Transmission electron microscopy (TEM) results reveal the decoration of CoFe2O4 nanoparticles on GO sheets. Magnetic response of nanocomposites was confirme from superconducting quantum interference device (SQUID) magnetometer measurement. Optical properties of these nanocomposites were investigated by Raman spectroscopy. Interfacial compressive stress involved in this system is evaluated from observed blue shift of characteristic G peak of graphene oxide. Increase in full width half-maximum ( FWHM) as well as up shift in D and G peaks are clear indicator of involvement of charge transfer process between GO sheets and dispersed magnetic nanoparticles. The effect of charge transfer process is quantified in terms of shifting of Fermi level of these nanocomposites. This is evaluated from variation in contact surface potential difference (CPD) using Scanning Kelvin probe microscopy (SKPM). XRD spectra of CoFe2O4/GO confirm the polycrystalline nature of CoFe2O4 nanoparticles. Lattice strain estimated from XRD peaks are correlated to the observed Raman shift.