Annealing temperature effects on BiFeO3 nanoparticles towards photodegradation of Eosin B dye.

BiFeO₃ is the model multiferroic material widely considered as nanoparticles for its potential photocatalytic activity. In this work, we study the influence of annealing temperature on the structural, morphological and optical properties of BiFeO₃ nanoparticles prepared by a facile chemical route and, the resulting photodegradation of Eosin B dye. When annealing temperature as low as 600 °C is used, some parasitic phases such as Bi₂Fe₄O₉ appear in addition to the BiFeO₃ phase. At the same time, the energy of the absorption onset and band gap shifts down and the photocatalytic activity toward Eosin B dye significantly increases by ∼27% when UV light is used while only a small if any, enhancement is observed in case of sunlight illumination. This photocatalytic enhancement could be therefore essentially attributed to the presence of secondary parasitic phases that could also explain previous reported observations. Furthermore, annealing at 500 °C to obtain pure parasitic-phase-free BiFeO₃ nanopowder reveals excellent photodegradation of Eosin B reaching 95% efficiency after 40 min under sunlight illumination with good photostability after three consecutive degradation cycles. [ABSTRACT FROM AUTHOR]