Band gap tuning of BaFe ₁₂ O ₁₉ with Mg and Mn doping to enhance solar light absorption for photocatalytic application

Abstract

Summary Mg and Mn ions doping were performed in barium hexaferrite (Ba1−xMgxFe12−yMnyO19) (x = 0.0, 0.30, 0.45, 0.60, 0.75, 0.90) and (y = 0.0, 0.15, 0.30, 0.45, 0.60, 0.75) via facile micro‐emulsion route. XRD analysis revealed the formation of single‐phase hexagonal geometry of Ba1−xMgxFe12−yMnyO19 with the successful doping of the Mg and Mn ions. The average crystallite size was 19.5 nm, which was increased by increasing the dopant contents. The functional groups were identified by FTIR analysis. The dopant contents (Mg and Mn) affected the dielectric properties Ba1−xMgxFe12−yMnyO19 and AC conductivity was increased, while dielectric loss, tangent loss, and resistivity were decreased as the concentration of dopant ions was increased. The Tauc's plot was used for the band gap estimation of Ba1−xMgxFe12−yMnyO19, the band gap values were decreased from 2.94 to 1.90 (eV) due to generation Fermi energy and change in the Ba2+ ions at the tetra‐ and octahedral locations. Photocatalytic activity (PCA) was performed under visible light by degrading Rhodamine B (RhB) dye. The RhB dye was degraded up to 85% within 50 minutes following the first order reaction kinetics with 0.0224 min−1 rate constant. The results revealed that the BaFe12O19 NPs the band gap can be tuned by doping the Mg and Mn ions to enhance the visible light harvesting for economical photocatalytic applications in various fields.

Zn/Mn co‐doped NiO synthesized by sol‐gel route for the photocatalytic degradation of methylene blue dye

“…As the availability of active sites enhanced the absorption of light and hence, higher the elimination of dye due to generation of higher hydroxyl radicals. As the amount of the catalyst increased up to 15 mg, the elimination of dye decreased because of the active sites being blocked due aggregates formation of the catalyst and reduction in the generation of hydroxyl radicals on the catalyst surface [43,44] …”

“…As the concentration of dye increased, the production of hydroxyl radicals (°OH) and UV light reaching the catalyst surface decreased leading to less photocatalytic activity. These factors contributed to the low efficiency of catalyst at high concentration of dye [43] …”

“…As the amount of the catalyst increased up to 15 mg, the elimination of dye decreased because of the active sites being blocked due aggregates formation of the catalyst and reduction in the generation of hydroxyl radicals on the catalyst surface. [43,44]…”

Photocatalytic activity of visible light active Sr-hexaferrite prepared by solid-state reaction and the pechini methods

“…The sample SrM-SGP showed a maximum absorption band at 274 nm, while in the sample SrM-SSR this band shifts to 279 nm. On the other hand, the band gap energy values of the samples were determined from the data obtained by the UV-vis technique using the indirect transition model by Tauc-plot, equation (4) [25][26][27].…”

“…Figure 6 shows the Tauc calculation to obtain the following band gap energy values recorded for the samples SrM-SGP (2.5 eV) and SrM-SSR (2.1 eV), respectively, which are the minimum energies required to activate the samples [7,21,27,29,30]. The unique confinement of the samples is responsible for the variation in band gap energy.…”