Improved luminescence and photocatalytic properties of Sm3+-doped ZnO nanoparticles via modified sol-gel route: A unified experimental and DFT plus U approach

In the current study, a modified sol-gel route was used to produce undoped and Sm3+ doped (1 mol%, 3 mol% and 5 mol%) ZnO nanoparticles (NPs). The study of opto-structural properties of Sm3+ doped NPs was carried out both experimentally and theoretically. Complete dissolution of Sm3+ ions into the ZnO lattice is obviously seen from X-ray diffraction (XRD) analysis. Morphological evolution with doping was studied using field emission scanning electron microscopy (FESEM) and transmission electron micro-scopy (TEM). X-ray photoelectron spectroscopy (XPS) was carried out to confirm the presence of Sm3+ on the doped NPs. Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing absorption in the visible range, and a minimum of 3.18 eV of optical bandgap for Zn0.97Sm0.03O is found. Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%, followed by an increase of Zn0.95Sm0.05O. Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra. Theoretical analysis was also carried out with density functional theory (DFT). This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully. Later, photocatalytic activity for the optimum composition, i.e., 3 mol %, was assessed experimentally.(c) 2022 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, undoped and Sm3+ doped ZnO nanoparticles were synthesized using a modified sol-gel route. The opto-structural properties of the doped nanoparticles were investigated both experimentally and theoretically. The results showed complete dissolution of Sm3+ ions into the ZnO lattice and morphological changes with doping. Increasing the dopant quantity resulted in a redshift of the nanoparticles, a decrease in bandgap, and increased absorption in the visible range. Photoluminescence spectroscopy revealed the recombination rate of electron-hole pairs. Theoretical analysis using density functional theory was also performed. The study provides insight into the structural properties of the synthesized nanoparticles and their enhanced photocatalytic activity.