Controlled dispersion of ZnO nanoparticles produced by basic precipitation in solvothermal processes

Abstract

Zinc oxide nanoparticles were successfully synthesized under precipitation processes, using ZnSO 4 ⋅7H 2 O as a Zn 2þ precursor and K 2 CO 3 used as a basic source, and hydrozincite was obtained as an intermediary, which was treated under two procedures; first procedure involved multiple stages to get final precipitated with NaOH, and in the second procedure the hydrozincite was straightforwardly dried at 220 C. By both processes ZnO structures were obtained, which were turned into nanoparticles by a solvothermal treatment, for four hours in ethylene glycol at 200 C. The final products for the first procedure was conglomerate of spherical nanoparticles with sizes ranged between 5-10 nm and dispersed ellipsoidal nanoparticles for the second procedure.Apart off the two procedures mentioned above, another synthesis was carried out with the same Zn 2þ precursor but now using NaOH, and the solvothermal treatment produced ZnO mixed micro-structures which under ultrasonic cavitation disaggregated on mesoporous ZnO nanoplates of hexagonal shapes with nanopore sizes of approximately 0.35 nm. All ZnOs synthesized were structurally characterized with XRD, TEM and FT-IR techniques, and electronically with UV-Vis absorption and diffuse reflectance spectroscopies.

UV-irradiated sol-gel spin coated AZO thin films: enhanced optoelectronic properties

“…The estimation of direct band gap energy was obtained using the use of Tauc's law [ 34 , 35 ]. Here, α is coefficient of optical bandgap, energy of incident photon is hν, C is a constant and E g is optical band gap.…”

Crystalline native defects in ZnO analyzed by photoluminescence applying Maxwell-Boltzmann statistics in the visible region

“…The stability of metal complex increases with decrease in size of the metal cations. Ionic radii of Zn 2+ ∼ 0.60 Å cation and CO 2− 3 (∼ 1.62 Å), S 2− (∼ 1.84 Å) ions [28]. These findings highlight the impact of the presence of H 2 O on the interaction of Zn 2+ cation and NH 3 molecules, in aqueous ammonia solution, which is an limitation with the hard/soft Lewis acids and bases classification of H 2 O being a hard L associated at NH 3 , which is attributed as being soft.…”

The Current Progresses and Future Perspectives of Photoreactors and Catalysts Used in Photocatalytic Reduction of CO2

“…These methods are the most widely used in industry due to the convenience of the synthesis process in which reaction parameters are adjusted to obtain the desired nanostructure. Chemical precipitation, solvothermal, sol–gel, pyrolysis, and thermal decomposition are commonly used chemical methods. Biosynthesis of zinc oxide nanostructures usually uses plant extracts and microorganisms to prepare the required structures. , Synthesis methods can also be classified as solution or gas phase methods depending on whether the reactants used are in a solution phase or a gas phase.…”