Tuning size and catalytic activity of nano-clusters of cobalt oxide

Abstract

Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of 4-6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency of the cobalt oxide was comparable with mesoporous cobalt oxides.

Wet Synthesis of Monodisperse Cobalt Oxide Nanoparticles

“…The average particle size calculated with the help of Debye-Scherrer equation was found to be 50 nm. It was observed that the peak intensity increases with a narrowing down particle size distribution with high purity on calcination [13]. The EDX supports the formation of CoO nanoparticle with a chemical composition in the ratio of 1 : 1 as supported by TEM and SAED technique which supports the presence of good compositional homogeneity in the nanoparticles.…”

Preparation of cobalt oxide thin films and its use in supercapacitor application

“…The FT-IR spectra revealed the characteristic absorption peaks for metal-oxygen bonding and oxygen-hydrogen bonding. The peaks around n1 (451 cm À1 ) and n2 (584 cm À1 ) are originating from the stretching vibrations of the metal-oxygen bond characteristic of the spinel metal oxide [16]. The absorption peaks at n3 (1450 cm À1 ), n4 (1605 cm À1 ) and n5 (3437 cm À1 ) are assigned to the bending vibration of NH 4 , bending vibration of molecular water and OH-stretching vibration, respectively [17,18].…”

Synthesis of cobalt oxide interconnected flacks and nano-worms structures using low temperature chemical bath deposition

“…The peaks around 5 (3315.74 cm −1 ) and 3 (1600.97 cm −1 ) are assigned to O-H stretching and bending modes of water, respectively [23]. The peaks around at 2 (599.88 cm −1 ) and 1 (399.49 cm −1 ) are due to the stretching vibrations of the metal-oxygen bond characteristic of the metal oxide [24]. The absorption peaks at 8 (667.79 cm −1 ) and 7 (578 cm −1 ) are assigned to the (Co-O) modes [25], and peak 6 (393.49 cm −1 ) assigned from stretching vibration of the metal-oxygen bond characteristics of the spinal metal oxide.…”