Energy-saving synthesis of wurtzite ZnS nanoparticles using Yttrium as a defect regulator by hydrothermal method

Abstract

In this work, Y-doped ZnS nanoparticles were synthesised using the hydrothermal method with doping percentages of 0.5%, 1%, 2.5%, and 5%. XRD study revealed that doping caused a phase transition from cubic to hexagonal, further confirmed by Raman analysis and TEM images. Morphological studies conducted by SEM and TEM provided insights into the structural changes. Diffused reflectance studies were used to evaluate the band gap, with values obtained as 3.33eV, 3.45 eV, 3.45 eV, 3.44 eV, and 3.37 eV for pure, 0.5%, 1%, 2.5%, and 5% Y-doped ZnS, respectively. Photoluminescence analysis revealed the presence of defect states in ZnS nanoparticles, indicated by peaks at 362 nm, 383 nm, and 390 nm in both pure and doped samples. The intensity of these peaks increased with Y doping, attaining its highest at 1% Y doping, while concentration quenching was observed at higher doping percentages. The EDAX analysis confirmed the successful integration of Y as a dopant in the ZnS lattice. These findings highlight the importance of optimizing the doping concentration to achieve the desired luminous features and provide valuable insights into the doping-dependent luminescence behaviour of Y-doped ZnS nanoparticles. The visible light photocatalytic activity of the nanoparticles was investigated, and it was revealed that the photocatalytic efficiency increased initially and then declined with the doping concentration increased. It was found that the ideal doping concentration for 93% degradation efficiency was 1%. The novelty of this work lies in developing a simple and energy-saving method for synthesizing hexagonal ZnS at low temperatures, which avoids the need for high temperatures and advanced anti-oxidation apparatus.