Synthesis of ZnO nanoparticles by liquid decomposition assisted by CW CO₂ laser

In this work, the zinc oxide nanoparticles (ZnONPs) were synthesized by using the liquid decomposition method with the assistance of a CW CO₂ laser at 10.6 μm and power 40 W. The synthesis process involved the use of 2.195 g of Zinc Acetate dihydrate (ZaACC) and 1.40185 g of synthesis-grade Hexamethylenetetramine (HeXa) in the production of ZnONPs within a 100 ml water solution. UV-Visible spectroscopy and FESEM were employed for analysis. It was found that the laser beam time had an effect on morphological and optical characteristics, and the particle size distribution for ZnONPs (powder and solution) at 3 and 6 min showed a particle size range of 5.4 to 16.3 nm, respectively. According to the EDX data, two elements were present in ZnO powder at 3 and 6 min: Zn (75.07%), O (24.93%), Zn (72.02%), and O (27.98%), respectively. For the ZnO solution at the same time points, the composition was Zn (71.14%), O (28.86%), Zn (64.28%), and O (35.72%), respectively. The optical results of the ZnO showed an absorption edge that displayed a redshift from 215.21 to 232.11 nm, exhibiting strong Near-UV absorption and an edge around 376 nm, with bandgap energies of 3.02 eV and 3.07 eV at 3 and 6 min respectively. The photoluminescence behavior observed in ZnONPs showed two peaks of 425 nm and 633 nm, respectively during longer growth times. Our results were compared with previous research utilizing alternative preparation techniques. Consequently, these efforts contribute to the synthesis, investigation, and control of the behavior of ZnONPs, resulting in their development for various applications, including biology, electronics, optoelectronics, and sensors.