Abstract

For the first time, nanocrystalline photocatalysts of spinel MgFe₂O₄, ZnFe₂O₄ and orthorhombic CaFe₂O₄ oxides were synthesized (at low temperature 973 K) by microwave sintering, in one sixtieth of the time required to that of the conventional method. A significantly improved crystallinity was obtained for the samples irradiated for longer duration of time (10–100 min). The theoretically computed electronic structure of the MFe₂O₄ (M: Ca, Zn, Mg) systems was respectively correlated with the experimental results obtained from their structural and photocatalytic characterization. The photocatalytic performance was found to be affected by surface area and crystallinity of the photocatalyst. The density functional theory (DFT) calculations of MFe₂O₄ lattices revealed that M-ion controllably affects the density of sates of the Fe–d orbitals near the Fermi level. Consequently they play an important role in determining the band-energetics and thus the visible light photocatalytic activity for methylene blue degradation.