A facile synthesis of undoped and 2.0 % selenium-doped zinc oxide nanoparticles (NPs) was efficaciously accomplished through a mechanochemical route using zinc acetate dihydrate, oxalic acid, and Se powder in a solid state reaction. After calcination at 450 °C, the obtained nanostructures were probed by X-ray diffraction, where the acquired data revealed the pertinence of the wurtzite hexagonal ZnO for both undoped (ZnO) and doped (Se/ZnO) NPs and crystallite sizes of 30 and 24 nm for ZnO and Se/ZnO, respectively. The formation of the target NPs was confirmed by the scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and the Fourier transformation infrared molecular vibrations data. The porosity investigations indicated 33.65 m2/g Brunauer–Emmett–Teller surface area, 197 Å pore diameter, and 0.172 cm3/g pore volume for the Se/ZnO NPs compared to lower values for the pristine ZnO. The band gap energies were 3.19 and 3.15 eV for ZnO and Se/ZnO as perceived from the Tauc plots of the UV-visible absorption measurements. The photodegradation of methylene blue dye under UV illumination was found to follow the pseudo–first-order kinetics with an enhanced performance by the doped samples as reflected by the higher (3.2 × 10−3 s−1) rate constant relative to the undoped sample (1.7 × 10−3 s−1). A photodegradation mechanism was suggested in the light of the band gap energy investigation. The obtained findings indicate the improvement of ZnO properties by doping with Se through a simplistic and inexpensive approach.

In this work a study was performed using UV/Vis spectrophotometer to determine the concentrations of caffeine in coffee, tea and chocolate milk available in local market in Riyadh, Saudi Arabia. Quantitative analysis was carried using dichloromethane as extracting solvent. Results showed that the minimum caffeine level was observed in the chocolate milk (16.38 ppm) and the highest caffeine content observes in coffee (32 ppm).

Silver decorated copper doped zinc oxide nanoparticles (Ag@Cu-ZnO) were successfully prepared via sol gel method. X-ray diffraction analysis revealed ZnO wurtzite crystalline structure with the existence of minor peaks attributed to Cu and Ag. The presence of Cu and Ag in addition to ZnO lattice was supplementary verified by EDS data while the shift in the FTIR band confirmed the Cu incorporation within the ZnO host lattice. Both SEM and XRD revealed an increase in particle size with Ag loading. At different frequencies, electrical measurements demonstrated a decrement in the dielectric constant, dielectric loss and AC conductivity with the increment of Ag content. Meanwhile, the Nyquist plots of the impedance measurement showed a single semicircle arc indicating the predominance of grain boundary resistance. This study elucidated the great influence of Ag on Cu-doped ZnO nanoparticles’ structural, dielectric constant and electrical conductivity which make it a promising candidate for catalytic, photocatalytic and adsorption applications.

Hierarchical porous flower-like ZnO structures containing ZnO nanorods were successfully synthesizedby precipitation process. The structure containing high aspect ratio nanorods was revealed by scanning electron microscopy(SEM). The EDS analysis revealed the ZnO nanostructures formation as confirmed by the Zn and O peaks. The Fourier-transform infrared spectroscopy(FTIR) spectrum indicated the Zn – O bond vibrational frequency. The typical hexagonal wurtzite ZnO nanostructure with 15 nm crystallite size and the characteristic parameters was perceived from the X-ray diffraction(XRD) data. A 10.13 m².g-1 surface area, 10.05 cm3/g pore volume and 18.25 nm pore diameter were estimated using nitrogen adsorption analysis. Bandgap energy of 3.229 eV was calculated from the optical analysis data. Under ultraviolet light irradiation, the prepared nanoparticles has effectively decolorized the methylene blue dye. The reaction obeyed the pseudo-first-order kinetics, and the degradation mechanism was proposed using radicals scavengers to determine the species involved in the photodegradation process such as isopropanol, p-benzoquinone, and dimethyl sulfoxide. The reactive oxygen atom in the mechanism of photodegradation , and the recyclability of ZnO photocatalysts were studied.