Structural, optical, magnetic, and photocatalytic analysis of exclusive metal aluminates against Congo Red dye under UV light

• Published in: Physica scripta 2024-10, Vol.99 (10), p.1059
• Main Authors: Ahlawat, Rachna, Goswami, Bindiya, Jangra, Nancy, Mohan, Bharti, Rani, Gita
• Format: Article
• Language: English
• Subjects: CR dye; magnetism; metal aluminates; photo-degradation; rietveld refinement
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/ad7a3e

The exclusive ZnAl 2 O 4 (ZAO), CaAl 2 O 4 (CAO), and MgAl 2 O 4 (MAO) nanocrystallites were prepared by the citrate sol–gel route and further annealed at 600 °C for 2 h. XRD and Rietveld refinement were conducted to explore the crystal structure and to optimize the profile parameters. FTIR confirmed the vibrational peaks of relevant functional groups. The additional stretching and bending IR modes in MAO sample emphasized structural disorders like antisites/native defects. The UV-DRS spectra of these samples analyzed the direct bandgap in 2.76–4.29 eV range. HR-TEM micrographs characterize the well-developed nanosized grains. From VSM data, several magnetic parameters were collected for prepared aluminates and found MAO as best ferromagnetic material with the highest coercive field value (1235 Oe). PL spectra of metal aluminates suggest that the broad peak in violet-blue is attributed to the band edge emission, and finite peaks in higher wavelength regions have appeared due to the large density of surface traps and oxygen vacancies. The photocatalytic mechanism of ZAO, MAO & CAO nanopowder was elucidated on the Congo Red dye (10–70 ppm) solution after exposure to UV light. The highest value of rate constant (k = 0.0118 min −1 ) suggests that the MAO (0.3 g l −1 ) sample would be an efficient photocatalyst (98%) under UV light owing to its large surface area (125 m 2 g −1 ) and suitable bandgap. The overall results advocate the practical applicability of aluminate photocatalysts in water treatment, spintronics, and photonics.