La-doped ZnO nanoparticles: unveiling structural and optical properties for advanced photocatalysis and sensing

• Published in: Journal of materials science. Materials in electronics Vol. 36; no. 19; p. 1176
• Main Authors: Thejaswini, M., Ranganatha, V. Lakshmi, Pramila, S., Sangamesha, M. A., Nagaraju, G., Chandra, N. Sharath, Mallikarjunaswamy, C.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2025; Springer Nature B.V
• Subjects: Catalytic activity; Characterization and Evaluation of Materials; Chemistry and Materials Science; Degradation; Doping; Dyes; Electromagnetic absorption; Electrons; Energy gap; Fourier transforms; Industrial wastes; Lanthanum; Materials Science; Methylene blue; Nanoparticles; Nitrates; Optical and Electronic Materials; Optical properties; Photocatalysis; Photocatalysts; Seeds; Spectrum analysis; Zinc oxide; India
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-025-15234-8

Using a semiconductor as a photocatalyst that reacts to visible radiation significantly eliminates pollutants from industrial wastewater. The advancement of nanotechnology has crucially affected the development of photocatalytic capabilities for zinc oxide nanoparticles (ZnO NPs). In this study, ZnO and Lanthanum-doped ZnO nanoparticles (La-ZnO NPs) were synthesized via a microwave-assisted process using Solanum melongena seed essence as an energy source. The doping concentration of La 3+ varied from 1 to 5 M%, showing that it enhanced the photocatalytic activity of ZnO NPs. The X-ray diffraction (XRD) results have shown the average crystalline size decreasing from 59 nm (pure ZnO) to 32 nm as the incorporation of La 3 ⁺ increases. The scanning electron microscopy (SEM) illustrates the sphere-shaped NPs and particle size reduced from 86 to 30 nm as the La 3+ percentage rises. Fourier transform infrared spectroscopy (FTIR) studies confirm the successful incorporation of La into the ZnO NPs. The UV–Vis excitation edge moved to an extended wavelength as the concentration of the La +3 ion and the band gap energy decreased from 3.1 (pure ZnO) to 2.85 eV. This demonstrates that La ion doping enhances visible light absorption. The methylene blue (MB) dye concentration decreased by increasing the illumination period of the photocatalysts. The La doping percentage increases with decreasing the percentage of degradation, so 5% La-ZnO NPs exhibit maximum degradation efficiency with the lowest recombination rate. This enhancement can be recognized as the integrated impact of La doping, prominent to an optimal band gap and possibly the greatest degradation of MB dye by La-ZnO NPs. The cyclic voltammetry plot of La-ZnO NPs explains the better sensing activity of the doped NPs than pure ZnO NPs.