BiFeO3-Black TiO2 Composite as a Visible Light Active Photocatalyst for the Degradation of Methylene Blue.

The application of a novel BiFeO3 (BFO)-black TiO2 (BTO) composite (called BFOT) as a photocatalyst for the degradation of methylene blue is reported. The p-n heterojunction photocatalyst was synthesized for the first time through microwave-assisted co-precipitation synthesis to change the molar ratio of BTO in BiFeO3 to increase the photocatalytic efficiency of the BiFeO3 photocatalyst. The UV-visible properties of p-n heterostructures showed excellent absorption of visible light and reduced electron-hole recombination properties compared to the pure-phase BFO. Photocatalytic studies on BFOT10, BFOT20, and BFOT30 have shown that they decompose methylene blue (MB) in sunlight better than pure-phase BFO in 70 min. The BFOT30 photocatalyst was the most effective at reducing MB when exposed to visible light (97%). Magnetic studies have shown that BTO is diamagnetic, and the BFOT10 photocatalyst exhibits a very weak antiferromagnetic behavior, whereas BFOT20 and BFO30 show diamagnetic behavior. This study confirms that the catalyst has poor stability and weak magnetic recovery properties due to the non-magnetic phase BTO in the BFO.

Microwave-Assisted Solvothermal Route for One-Step Synthesis of Pure Phase Bismuth Ferrite Microflowers with Improved Magnetic and Dielectric Properties.

The prototypical plum-free, one-phase multiferric ferrite BiFeO3 (BFO) is solid, parallel, with a high ferroelectric Curie temperature and Neel temperature and antiferromagnetic and ferroelectric propagation. This work aims to synthesize pure-phase BFO in the quickest possible way. We followed the microwave-assisted solvothermal (MWAST) method to achieve pure-phase BFO in the shortest duration of 3 min. The experiment involves simple optimizations with KOH concentration and microwave power levels. The surface morphology along with magnetic properties of BFO synthesized via the MWAST method are altered with varying KOH concentrations and microwave (MW) power levels. Our X-ray diffraction findings reveal that the pure-phase BFO is formed at 800 W MW power, and the structural characterizations like transmission electron microscopy, field emission scanning electron microscopy with energy-dispersive X-ray analysis have displayed the formation of uniformly distributed spherical microflowers of pure-phase BFO exhibiting a single-crystalline nature. Besides, the magnetic measurements affirmed a reliable weak ferromagnetic behavior (magnetization ∼1.25 emu/g) in BFO synthesized at 800 W MW power. In addition, good dielectric behavior with low dielectric loss was accompanied by frequency-dependent dielectric studies indicating an excellent frequency response of the material, and also the room-temperature ferroelectric properties were studied using a ferroelectric analyzer. The polarization of pure-phase BFO increases with the applied electric field and exhibits unsaturated polarization-electric field loops due to leakage current. Moreover, the Fourier transform infrared spectrum of the synthesized material has indicated the pure-phase BFO, and the Raman data have elucidated the vibrational modes of BFO. Further, the analysis of X-ray photoelectron spectroscopy data has confirmed the presence of fewer Fe2+ ions and oxygen vacancies in the pure-phase BFO. Therefore, the collective characterizations and detailed analysis of BFO material have revealed the uniqueness of the MWAST method in producing the pure-phase BFO in 3 min with improved magnetic and dielectric properties, and hence the BFO synthesized via the MWAST method can be a potential candidate for multiferroic applications.