Quenching Medium Effect on the Functional Properties of Pure and Doped ZnO Particles

The semiconductor zinc oxide (ZnO), is a versatile material mostly used for medicine applications, such as cancer treatments like the Photodynamic Therapy (PDT). Due to obtain the material’s optimum functional properties, the effect in quenching medium have been further investigated. Pure and ZnO doped with Li (5% at.) and Ti (9% at.) nanoparticles (nps) were synthetized based in a modified polyol route. This nps were quenched at the following four conditions fixed in combination of two: time reactions (t_rxn) of cero (0) or thirty (30) minutes and quenching with water and ice or with cold water. X-ray diffraction (XRD) confirmed the ZnO-wurzite formation and its crystallinity for all conditions. The UV-Vis spectroscopy showed better blue-shifted exciton at conditions of water and ice for both times of reaction: 30 and 0 mins with an average exciton peak for all species of 355 and 352nm respectively, suggesting smaller average particle size and a high band gap. Lastly, the photoluminescence (PL) spectra revealed two emission peaks at 363nm and 390nm corresponding to the electrons’ recombination and the zinc interstitials (Zn_i) in the host oxide structure. Predominance of the 363nm peak was more favorable at conditions of ice and water quenching with a t_rxn = 30 mins. This emission peak is responsible of the generation of the materials’ free radicals for the production of radioactive species responsible to eliminate cancerous cells. Ultimately, the most favorable quenching effect was the condition of water and ice quenching at a t_rxn = 30 minutes for all pure and ZnO doped nanoparticles. Thus, the effect of quenching can optimize the synthesized material to obtain a greater yield of cytotoxic species.