US EPA

1549292 

Journal Article 

Effect of pH on solvothermal synthesis of beta-Ni(OH)(2) and NiO nano-architectures: Surface area studies, optical properties and adsorption studies 

Kalam, A; Al-Shihri, AS; Al-Sehemi, AG; Awwad, NS; Du, G; Ahmad, T 

2013 

1 

Superlattices and Microstructures
ISSN: 0749-6036 

55 

83-97 

10.1016/j.spmi.2012.11.024 

WOS:000315316200010 

We report here a simple and modified solvothermal synthesis
of NiO nanoparticles by using nickel nitrate hexahydrate [Ni(NO3)(2)-center dot 6H(2)O],
hexamethylenetetramine [C6H12N4], sodium hydroxide [NaOH] and ethanol [C2H5OH] as refluxing
solvent. Nickel hydroxide [beta-Ni(OH)(2)] nanostructures were first formed which were then
calcined at 400 degrees C to obtain nickel oxide (NiO) nanoparticles. The nano-powder was
investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron
microscopy, high-resolution transmission electron microscopy, Fourier transform infrared
spectroscopy, ultraviolet-visible spectroscopy and Brunauer-Emmett-Teller surface area studies.
The size of the NiO nanoparticles was estimated by X-ray powder diffraction pattern, which was in
close agreement with the particle size obtained by transmission electron microscopy analysis.
Scanning electron microscopy studies revealed that the synthesized nickel oxide nanostructures
showed various morphologies and the morphologies can be easily tailored by adjusting the pH
value. The chemical structure information of the products was studied by Fourier transform
infrared spectroscopy. Electronic spectra were used to clarify qualitatively the change in
absorption band positions on changing the particle size of NiO. The values of the optical band
gap of the NiO nanoparticles increases from 2.9 to 3.5 eV as the particle size decreases and
indicated a direct transition. The specific surface area of NiO nanoparticles was found to
increase from 58.3 to 131.4 m(2)/g with decrease in the particle size from 20 nm to 5 nm. It also
exhibited excellent adsorption of Co(II) and Pb(II), demonstrating a promising application in
waste water treatment. (c) 20112 Elsevier Ltd. All rights reserved. 

Nickel oxide nanoparticles; X-ray diffraction; Electron microscopy; Optical properties; Surface area studies and adsorption