Nanostructured maghemite and magnetite and their nanocomposites with graphene oxide for photocatalytic degradation of methylene blue

A wet chemical route was utilized to synthesize iron oxide nanoparticles for the photocatalytic degradation of the Methylene Blue (MB) dye. The former (γ-Fe2O3) was also used to fabricate composite with graphene oxide (GO). X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) were used to confirm the prepared compounds and their composites with GO. XRD confirmed the crystalline structure with the corresponding patterns and other physical parameters. The wider peaks showed the less crystallite size of prepared samples. SEM images showed that the nanoparticles have relatively spherical morphology. The size estimated from the SEM images was in the range of 70–100 nm. The surface properties such as specific surface area and pore size were also determined by N2 adsorption-desorption measurements. The specific surface areas determined from BET analysis were 50 m2/g and 73 m2/g for iron oxide nanoparticles and their composite with GO, respectively. High surface area provided more attachment sites for the adsorption of methylene blue (MB) molecules with γ-Fe2O3 @ GO. Further GO suppressed the aggregation of iron oxide nanoparticles. UV spectroscopic analysis led towards band gap energy value which motivated the optical properties of the nanoparticles. As the nanodomain of particles was lowered, the band gap values increased. Therefore the efficacy of γ-Fe2O3 @ GO nanomaterials was improved. The photodegradation of MB by γ-Fe2O3 @ GO was observed up to 90.6% compared to γ-Fe2O3 and Fe3O4 nanoparticles. Easy electronic conduction from valence band to conduction band and suppression of charge carrier recombination at photocatalyst surface could also increase the photocatalytic activity of photocatalyst.