Joel 2100

Transmission electron microscopy (TEM) was carried out using JOEL-2100, Tokyo, Japan at 200 kV. Scanning electron microscopic (SEM) analysis was performed using JSM 6510LV (JEOL, Tokyo, Japan). UV spectra of synthesized ZnO-NPs were taken by using UV–vis spectrophotometer-UV5704S from Electronics, India Ltd. X-ray diffraction (XRD) was performed using Mini Flex™ II XRD system, Rigaku Corporation, Tokyo, Japan. Fourier-transform infra-red spectroscopy (FTIR) analysis was performed on PerkinElmer FTIR spectrometer Spectrum Two (Perkin Elmer Life and Analytical Sciences, Shelton, CT, USA).

Specific surface area and pore size distribution of samples, was calculated using the BET method from N₂ adsorption/desorption isotherms obtained using a static volumetric adsorption analyzer (Micromeritics ASAP 2010, Shanghai, China). Morphology and microstructure of the as-prepared samples was determined via a scanning electron microscope (SEM; S4800, Hitachi, Japan) and high-resolution transmission electron microscope (HR-TEM; Joel-2100, JEOL, Japan). Crystal structures were analyzed by X-ray diffraction (XRD, RIGAKU miniflex/600, Japan) in the range between 20° and 80°. Thermogravimetric analysis was conducted on a TGA Q5000 (American TA instrument Q Series) to better understand phase transformations during calcination. Optical properties of samples, were examined using a Cary 500 UV–vis NIR spectrophotometer in the range 200–800 nm. The chemical states of elements at the near surface of samples were also studied using X-ray photoelectron spectroscopy (XPS, Phi 5000C ESCA system, USA).