Single Step Synthesis of High-Purity CoO Nanocrystals
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- 作者：Huaming Yang ; Jing Ouyang ; Aidong Tang
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：July 19, 2007
- 年：2007
- 卷：111
- 期：28
- 页码：8006 - 8013
- 全文大小：692K
- 年卷期：v.111,no.28(July 19, 2007)
- ISSN：1520-5207
文摘
Both octahedral and slice-shaped cubic cobalt monoxide (CoO) nanocrystals with narrow size distributionshave been successfully synthesized by a simple solvothermal route. It was found that conditions of thesolvothermal treatment showed obvious effects on the formation and purity of the as-synthesized CoOnanocrystals, only when cobalt acetate was used as the cobalt source and when temperature reached 190 
Ccould CoO be produced; also, freeze-drying was necessary for obtaining pure CoO. Size of the CoO nanocrystalsvaried from 30 to 130 nm. Morphology of the products could be controlled by simply changing the type ofsurfactant in solvent, and the octahedral CoO nanocrystals showed rounded turns. Purity of the products wasdetected by intensive X-ray photoelectron spectroscopy (XPS) investigation and Fourier transform infraredspectroscopy (FTIR) combined with differential scanning calorimetry/thermal gravity (DSC/TG). The resultsindicated an absence of unexpected trivalence cobalt series on surface of the samples, thanks to the protectionof the surface by trace amount of carbonate ions, adsorbed hydroxylation, and surfactant with a maximumthickness of 2 nm, which were proved by high-resolution transmission electron microscopy (HRTEM). Theas-synthesized CoO nanoparticles were added into positive electrode of Ni/MH batteries, and discharge/charge cycling tests were performed under different rates from 0.1C to 5.0C. The results indicated that thespecific capacities of batteries with addition of 5% octahedral or slice CoO nanocrystals at 0.1C were 393.3and 318.1 mAh/g, respectively, which were higher than that without CoO (269.2mAh/g). Specific capacity ofbattery with addition of 5% octahedral CoO nanocrystals was 40% higher than that without CoO at 5.0C.Octahedral CoO nanocrystals show better electrochemical activity than slice CoO and indicate interestingpotential in the field of electrochemical application.
Ccould CoO be produced; also, freeze-drying was necessary for obtaining pure CoO. Size of the CoO nanocrystalsvaried from 30 to 130 nm. Morphology of the products could be controlled by simply changing the type ofsurfactant in solvent, and the octahedral CoO nanocrystals showed rounded turns. Purity of the products wasdetected by intensive X-ray photoelectron spectroscopy (XPS) investigation and Fourier transform infraredspectroscopy (FTIR) combined with differential scanning calorimetry/thermal gravity (DSC/TG). The resultsindicated an absence of unexpected trivalence cobalt series on surface of the samples, thanks to the protectionof the surface by trace amount of carbonate ions, adsorbed hydroxylation, and surfactant with a maximumthickness of 2 nm, which were proved by high-resolution transmission electron microscopy (HRTEM). Theas-synthesized CoO nanoparticles were added into positive electrode of Ni/MH batteries, and discharge/charge cycling tests were performed under different rates from 0.1C to 5.0C. The results indicated that thespecific capacities of batteries with addition of 5% octahedral or slice CoO nanocrystals at 0.1C were 393.3and 318.1 mAh/g, respectively, which were higher than that without CoO (269.2mAh/g). Specific capacity ofbattery with addition of 5% octahedral CoO nanocrystals was 40% higher than that without CoO at 5.0C.Octahedral CoO nanocrystals show better electrochemical activity than slice CoO and indicate interestingpotential in the field of electrochemical application.