Investigations on structural, optical and magnetic properties of solution-combustion-synthesized nanocrystalline iron molybdate

Iron molybdate β -Fe 2 (MoO 4 ) 3 nanoparticles were synthesized by exploiting the self-propagating high-temperature combustion strategy using hexamine as a fuel. The obtained β -Fe 2 (MoO 4 ) 3 nanoparticles exhibited the orthorhombic crystalline structure, which is evidenced from the XRD pattern. FT-IR spectrum revealed the existence of stretching and bending vibrations of Mo–O–Mo and O–Mo–O bonding in the nanocrystals. The binding energy peaks in the X-ray photoelectron spectroscopy (XPS) spectrum positioned at 710 and 725, 231 and 235 and 530 eV, respectively, correspond to the Fe(2p), Mo(3d) and O(1s) orbitals. Absorption spectrum of nanoparticles showed adequate absorbance of visible region photons of the nanoparticles and also optical bandgap value of β -Fe 2 (MoO 4 ) 3 nanoparticles as 2.26 eV, which is calculated using the Kubelka–Munk function. The existence of Fe 3+ and Mo 6+ in β -Fe 2 (MoO 4 ) 3 is authenticated with the aid of electron paramagnetic resonance spectrum measurements. The obtained nanoparticles have showed methylene blue dye degradation of 98.4% under sunlight irradiation.