Cobalt-doped zirconium dioxide nanoparticles: enhancement of structural and optical properties, as well as radiative efficiency, for photocatalysis and radiation shielding applications

Abstract

This study demonstrates how cobalt doping imparts dual functionality, enhanced photocatalytic performance, and improved gamma radiation shielding of ZrO₂ nanoparticles. The synthesized materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The XRD pattern of ZrO₂ shows a tetragonal phase structure with well-defined lattice features and a strong diffraction peak along the (101) orientation. The peak intensities decreased with increasing cobalt concentrations upon doping with cobalt ions without introducing any additional peaks or cobalt-related phase transitions. With increasing Co concentrations, the crystallite sizes decrease from 22 to 13 nm. Also, the energy bandgap was found to be 4.52 eV and then reduced to 3.96 eV with increasing cobalt content. Photocatalytic performance was evaluated, and the best sample was ZC-15, with a methylene blue degradation rate of 92% and a first-order rate constant of 20.3 × 10⁻³ min⁻¹. This finding provides insights into the variation of photocatalytic activity and highlights the Co-doping strategy’s effectiveness and potential in enhancing the performance of ZrO₂-based photocatalysts. In addition, gamma radiation shielding properties of cobalt-doped ZrO₂ nanoparticles was studied at several energies to evaluate their shielding effect with linear mass attenuation coefficients that increased with increasing Co content. The ZC-15 sample showed maximum attenuation and is a suitable candidate for utilization in radiation shields.