This article reports the controlled size of ZnO nanoparticles synthesized via simple aqueous chemical route without the involvement of any capping agent. The effect of different calcination temperatures on the size of the ZnO nanoparticles was investigated. X-ray diffraction (XRD) results indicated that all the samples have crystalline wurtzite phase, and peak broadening analysis was used to evaluate the average crystallite size and lattice strain using Scherrer's equation and Williamson–Hall (W–H) method. Morphology and elemental compositions were investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy. The average crystallite size of ZnO nanoparticles estimated from Scherrer's formula and W–H analysis was found to increase with the increase in calcination temperature. These results were in good agreement with AFM results. Optical properties were investigated using UV–vis spectroscopy in diffused reflectance (DR) mode, with a sharp increase in reflectivity at 375nm and the material has a strong reflective characteristic after 420nm at 500°C calcination temperature. Furthermore, photoluminescence spectroscopic results revealed intensive ultraviolet (UV) emission with reduced defect concentrations and a slight shifting in band gap energies with increased calcination temperature from 200°C to 500°C. This study suggests that the as-prepared ZnO nanoparticles with bandgap tunability might be utilized as window layer in optoelectronic devices

Copper oxide nanoflowers (CuO-NFs) have been synthesized through a novel green route using Tulsi leaves-extracted eugenol (4-allyl-2-methoxyphenol) as reducing agent. Characterizations results reveal the growth of crystalline single-phase CuO-NFs with monoclinic structure. The prepared CuO-NFs can effectively degrade methylene blue with 90% efficiency. They also show strong barrier against E. coli (27 ± 2 mm) at the concentration of 100 µg mL⁻¹, while at the concentration of 25 µg mL⁻¹ weak barrier has been found against all examined bacterial organisms. The results provide important evidence that CuO-NFs have sustainable performance in methylene blue degradation as well as bacterial organisms.

Nanomaterials are used for the miniaturization of particular electronic device. But new era of technology demands a cheaper and more commercial method to produce excellent material especially silicon dioxide. The present work deals with the sol-gel synthesis of SiO2 material and also provides a basic understanding of the effect of calcination temperature on the growth of SiO2 by hydrolysis of TEOS with ethanol, deionized water and catalyst mixture. The properties of resulting materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), AFM and optical properties through UV-visible spectroscopy and Photo Luminescence (PL). The XRD study of pure SiO2 with calcination temperature at 300ºC shows well crystalline characteristics and having hexagonal crystal structure. SEM results show obtained silica particles were having spherical morphology. The proper temperature the PL intensity was reduced and the shape of the emission spectrum slightly split into sharp peaks. UV-visible absorbance spectra of the silica samples having wide band gap showing absorbance in the ultra violet region. The degradation of methylene blue was selected as a test reaction to confer the photocatalytic activity of as obtained SiO2 samples. The results showed a strong correlation between the structure evolutions, crystallite size and photo degradation performance of SiO2. Although the photo degradation of silica calcined sample was found faster rate of MB breakdown than that of dried sample under visible irradiation.