PEG-directed microwave-assisted hydrothermal synthesis of spherical α-Ni(OH)2 and NiO architectures

Spherical alpha-Ni(OH)(2) architectures were synthesized by the microwave-assisted hydrothermal technique using PEG-6000 as the surfactant. NiO architectures with similar morphology were obtained by a simple thermal decomposition process of the precursor alpha-Ni(OH)(2) at 400 degrees C for 2 h and were confirmed by the X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) revealed that the synthesized spherical alpha-Ni(OH)(2) and NiO architectures were composed of stacked lamellar sheets and transmission electron microscopy (TEM) showed that the alpha-Ni(OH)(2) and NiO architectures were polycrystalline. The effect of the PEG-6000 concentration on particle size was investigated and it was found that the average particle size of alpha-Ni(OH)(2) architectures decreased from 4.689 mu m at C-PEG = 2 mmol L-1 to 3.907 mu m at C-PEG = 4 mmol L-1, and the corresponding average particle size of NiO decreased from 2.818 mu m to 2.492 mu m. The optical absorption band gap of NiO architectures was determined to be about 2.7-3.0 eV by UV-vis spectroscopy. Crown Copyright (C) 2012 Published by Elsevier Ltd and Techna Group S.r.l. All rights reserved.