Tuning the Band Gap of Cerium Oxide Nanoparticles Via Terbium (Tb) Doping: Experimental and Theoretical Insights

Abstract Cerium oxide nanoparticles (CNPs) exhibit remarkable electronic and optical properties; however, their wide band gap and high recombination rates hinder their photocatalytic efficiency. In this study, we investigate the effects of terbium (Tb) doping on cubic CNPs synthesized via the hydrothermal method to overcome these limitations. Elemental analysis using Fourier Transform Infrared Spectroscopy (FTIR) and Energy-Dispersive X-ray Spectroscopy (EDX) confirms successful Tb incorporation, while structural characterization through X-ray Diffraction (XRD) and Raman spectroscopy reveals the coexistence of Tb³⁺ and Tb⁴⁺ within the CNP lattice. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) demonstrate a reduction in nanoparticle size with increasing Tb content. Optical band gap measurements, obtained via Diffuse Reflectance Spectroscopy (DRS) and supported by Density Functional Theory (DFT) calculations, indicate a significant band gap reduction, enhancing visible light absorption. By systematically analyzing the effects of Tb doping at 8% and 12% concentrations on cubic CNPs, this study provides valuable insights into the structural, electronic, and optical modifications induced by doping. These findings suggest that Tb-doped CNPs hold great potential for improved photocatalytic and optical applications. Keywords: Cerium Oxide Nanoparticle (CNP); Doping; Band Gap; Characterizations; DFT Calculations