The ferroelectricity of multivalent codoped Bismuth ferrite (BiFeO₃; BFO) nanoparticles (NPs) is revealed and utilized for photocatalysis, exploiting their narrow electronic bandgap. The photocatalytic activity of ferroelectric photocatalysts BiFe_0.95Mn_0.05O₃ (BFM) NPs and mono‐, di‐, or tri‐valent cations (Ag⁺, Ca²⁺, Dy³⁺; MDT) coincorporated BFM NPs are studied under ultrasonication and in acidic conditions. It is found that such doping enhances the photocatalytic activity of the ferroelectric NPs approximately three times. The correlation of the photocatalytic activity with structural, optical, and electrical properties of the doped NPs is established. The increase of spontaneous polarization by the mono‐ and tri‐valent doping is one of the major factors in enhancing the photocatalytic performance along with other factors such as stronger light absorption in the visible range, low recombination rate of charge carriers, and larger surface area of NPs. A‐site doping of BFO NPs by divalent elements suppresses the polarization, whereas trivalent (Dy³⁺) and monovalent (Ag+) cations provide an increase of polarization. The depolarization field in these single domain NPs acts as a driving force to mitigate recombination of the photoinduced charge carriers.

The escalated photocatalytic (PC) efficiency of the visible light absorber Ba-doped BiFe_0.95Mn_0.05O₃ (BFM) nanoparticles (NPs) as compared to BiFeO₃ (BFO) NPs is reported for the degradation of the organic pollutants rhodamine B and methyl orange.

A complete photocatalytic degradation of dibutyl phthalate (DBP) using ferroelectric doped‐bismuth ferrite‐ (BiFeO₃; BFO) graphene oxide (GO) nanocomposites is achieved. The local ferroelectric properties of doped BFO photocatalysts supported onto GO is well‐utilized for photodegradation of pollutant. A complete photodegradation of DBP under ultraviolet light irradiation is achieved within 2.5 h, traced by gas chromatography. The best photocatalytic activity of Bi_0.95Ag_0.05Fe_0.95Mn_0.05O₃‐GO (ABMGO) nanocomposite is attributed to its large intrinsic local ferroelectric polarization, which suppresses the recombination of photoinduced charge carriers and the presence of Ag⁺ and Mn⁴⁺ as new active sites on the large surface of ABMGO speeds up the photodegradation of DBP. The possible mechanism of photodegradation of DBP is presented using mass spectrometry includes several intermediate products; phthalic acid, benzoic acid, benzaldehyde, and hydroquinone and 3‐methyl butyric acid which are harmless for the environment compared to DBP.

Highly crystalline BiFeO₃ (BFO), Bi_0.97Sm_0.03FeO₃ (Sm-BFO) and BiFe_0.97Co_0.03O₃ (Co-BFO) nanoparticles (NPs) were utilized as potential magnetic hyperthermia agents at two different frequencies in the radiofrequency (RF) range, and the effect of Sm³⁺ and Co²⁺ ion doping on the physical properties of the material was examined. The thermal behaviour of the as-prepared powders disclosed that the crystallization temperature of the powders is affected by the incorporation of the dopants into the BFO lattice and the Curie transition temperature is decreased upon doping. Vibrational analysis confirmed the formation of the R3c phase in all compounds through the characteristic FT-IR absorbance bands assigned to O–Fe–O bending vibration and Fe–O stretching of the octahedral FeO₆ group in the perovskite, as well as through Raman spectroscopy. The shift of the Raman-active phonon modes in Sm-BFO and Co-BFO NPs indicated structural distortion of the BFO lattice, which resulted in increased local polarization and enhanced visible light absorption. The aqueous dispersion of Co-BFO NPs showed the highest magnetic hyperthermia performance at 30 mT/765 kHz, entering the therapeutic temperature window for cancer treatment, whereas the heating efficiency of all samples was increased with increasing frequency from 375 to 765 kHz, making our doped nanoparticles to be suitable candidates for potential biomedical applications.