Mono‐, Di‐, and Tri‐Valent Cation Doped BiFe_0.95Mn_0.05O₃ Nanoparticles: Ferroelectric Photocatalysts

Abstract 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.