Photocatalytic study and superparamagnetic nature of Zn-doped MgFeO colloidal size nanocrystals prepared by solvothermal reflux method.

Biocompatible MgZnFeO (x=0.2, 0.4, 0.5, 0.6 & 0.8) nanoparticles were synthesized by solvothermal reflux method. All compounds were crystallized in cubic spinel structure with slightly enhance of lattice parameter with biocompatible substituent Zn concentration. All compounds were shown spherical geometry with average particle diameter is around 12nm (colloidal size). The spinel structure formation was confirmed by X-ray diffraction,electron diffraction, infrared, Raman shift measurements. Infrared analysis shows oleic acid coating on the surface of nanoparticles and TGA analysis shows that oleic acid desorbs from nanoparticle by decomposition at around 400°C. UV-Vis-NIR spectra show all the compounds show energy band gap in the semiconductor range (≈ 1.9eV). All compounds show superparamagnetic characteristics at room temperature with enhanced saturated mass magnetization (M) with Zn concentration up to x=0.5 and then reduces with further enhance of x up to 0.8. The M changes were ascribed to occupation of Zn at tetrahedral sites and proportional enhance of Fe at octahedral sites. The enhanced Fe concentration at octahedral sublattice leads to formation Fe-O-Fe networks which favor antiferromagnetic interactions due to superexchange phenomenon. Photocatalytic activity of all compounds were studied through methylene blue (MB) degradation analysis. All compounds show ≈ 96% degradation of MB upon 70min irradiation of light on photoreactor vessel. In addition, photocatalytic activity (degradation efficiency) enhances with Zn concentration in MgFeO. The Zn substitution enhances both M and photocatalytic activity biocompatible of MgFeO nanoparticles.