High-Yield Preparation of Uniform Cobalt Hydroxide and Oxide Nanoplatelets and Their Characterization

Abstract

Cobalt hydroxide nanoplatelets with a uniform hexagonal shape were prepared in high yield ( approximately 95%) by a facile hydrothermal route in the presence of poly(vinylpyrrolidone). This method provides a simple, low-cost, and large-scale route to produce beta-cobalt hydroxide nanoplatelets with an average diameter of 280 nm and a thickness of ca. 26 nm which show a predominant well-crystalline hexagonal brucite-like phase. Their thermal decomposition produced anisotropic nanoplatelets of cobalt oxides (CoO and Co3O4) under designed temperatures. The products were characterized by transmission electronic microscopy, selected-area electron diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetric, and thermogravimetric analysis. The magnetic properties of the products were investigated by a superconducting quantum interference device magnetometer. Co3O4 nanoplatelets exhibit a superparamagnetic behavior, and they might be a promising material to study the magnetic tunneling effect as anisotropic nanostructures.

Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

“…The freshly precipitated cobalt hydroxide slurry on (i) exposure to air, (ii) ageing in alkaline solution or mother liquor results in the formation of CoOOH [13]. Nanocrystalline cobalt hydroxide platelets were prepared by the hydrothermal treatment technique in presence of amines and polyvinylpyrrolidine [14,15]. There are several reports on the thermal decomposition studies of cobalt hydroxide, cobalt oxyhydroxide and cobalt based layered double hydroxides in relation to texture, morphology by electron diffraction, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy [16][17][18][19].…”

Effect of anions on the morphology of Co3O4 nanostructures grown by hydrothermal method and their pH sensing application

“…Co3O4 nanostructures are expected to show even more excellent and tunable properties due to their versatile morphologies and structures. So far, many interesting nanostructures of Co3O4, including nanowires/nanorods [16,17], nanotubes [18,19], nanocubes [20][21][22], nanospheres [23][24][25], nanoplates [26] and nanowalls [27], have been prepared by using different growth methods. He et al synthesized Co3O4nanocrystals by a solubility controlled method using surfactant [28].…”

Preparation of self-assembled cobalt hydroxide nanoflowers and the catalytic decomposition of cyclohexyl hydroperoxide

“…Ohta et al synthesized b-Co(OH) 2 nanoplatelets by a hydrothermal route in the presence of poly(vinylpyrrolidone). 17 Zeng's group reported butterfly-like b-Co(OH) 2 by ethylenediamine-mediated synthesis.…”