Structural and Photocatalytic Studies on Oxygen Hyperstoichiometric Titanium-Substituted Strontium Ferrite Nanoparticles

• Published in: Magnetochemistry 2022-10, Vol.8 (10), p.120
• Main Authors: Grewal, Jaspreet Kaur, Kaur, Manpreet, Sharma, Rajeev K, Oliveira, Aderbal C, Garg, Vijayendra Kumar, Sharma, Virender K
• Format: Article
• Language: English
• Subjects: Adsorption; Analysis; Carrier density; Chemical synthesis; Current carriers; Delta ferrite; Ferrites (Magnetic materials); Fourier transforms; Light; Magnetic properties; Mechanical properties; Methods; Microscopy; Mossbauer spectroscopy; Mössbauer spectroscopy; Mössbauer studies; Nanoparticles; nitroaromatics; Nitrophenol; Nonstoichiometric compounds; Optical properties; Oxygen; oxygen hyperstoichiometry; Photocatalysis; Photodegradation; Photoluminescence; Pollutants; Sol-gel processes; Spectrum analysis; Strontium; Structure; Substitutes; Titanium; Titanium compounds; titanium-substituted strontium ferrite; Ultraviolet radiation
• ISSN: 2312-7481; 2312-7481
• DOI: 10.3390/magnetochemistry8100120

Doping of ferrites is an important domain of research for their application as photocatalysts. In the present work, the effect of Ti4+ substitution on the structural and photocatalytic properties of strontium ferrite nanoparticles (NPs) is studied. Ternary doped Sr1−xTixFe2O4+δ ferrite NPs (x = 0.0–1.0) were synthesized by sol–gel methodology. Tetravalent Ti4+ ions caused oxygen hyperstoichiometry and enhancement in the surface area from 44.3 m2/g for SrFe2O4 NPs to 77.6 m2/g for Sr0.4Ti0.6Fe2O4+δ NPs. The average diameter of NPs ranged between 25–35 nm as revealed by TEM analysis. The presence of two sextets in the Mössbauer spectrum of pristine SrFe2O4 and Ti4+-substituted ferrite NPs and a paramagnetic doublet in the TiFe2O5 confirmed their phase purity. The photocatalytic potential of pure and Ti4+-substituted ferrite NPs was studied using nitroaromatic compounds, viz. pendimethalin, p-nitrophenol and Martius yellow, as model pollutants. Doped ferrite NPs with a composition of Sr0.4Ti0.6Fe2O4+δ NPs showed the highest degradation efficiency ranging from 87.2% to 94.4%. The increased photocatalytic potential was ascribed to the lowering of band gap (Eg) from 2.45 eV to 2.18 eV, a fourfold decrease in photoluminescence intensity, increased charge carrier concentration (4.90 × 1015 cm−3 to 6.96 × 1015 cm−3), and decreased barrier height from 1.20 to 1.02 eV. O2●− radicals appeared to be the main reactive oxygen species involved in photodegradation. The apparent rate constant values using the Langmuir–Hinshelwood kinetic model were 1.9 × 10−2 min−1, 2.3 × 10−2 min−1 and 1.3 × 10−2 min−1 for p-nitrophenol, pendimethalin and Martius yellow, respectively. Thus, tuning the Ti4+ content in strontium ferrite NPs proved to be an effective strategy in improving their photocatalytic potential for the degradation of nitroaromatic pollutants.