1120-43-0Relevant articles and documents
Insights into the thermal decomposition of Co(II) oleate for the shape-controlled synthesis of wurtzite-type CoO nanocrystals
Buck, Matthew R.,Biacchi, Adam J.,Schaak, Raymond E.
, p. 1492 - 1499 (2014)
Fatty acid salts of transition metals are known to undergo thermal decomposition in high-boiling organic solvents. Although it is a straightforward, promising approach for generating colloidal metal oxide nanocrystals in high yield, its widespread implementation is hindered by irreproducibility. Subtle structural variations and impurities are often introduced during preparation of the carboxylate precursors, which exhibit strong influence on thermal decomposition, and the resulting nucleation and growth of oxide nanocrystals. Here, we studied the colloidal synthesis of wurtzite-type CoO (wz-CoO) nanostructures via thermal decomposition of Co(II) oleate complex [Co(OL)]2. Using Fourier transform infrared spectroscopy, we discovered that the conventional method for preparing [Co(OL)]2 gives rise to an isolable impurity containing a free hydroxide moiety. Furthermore, [Co(OL)]2 did not thermally decompose within the expected temperature range when the impurity was removed. In contrast, pencil-shaped wz-CoO nanorods were synthesized when no measures were taken to remove the impurity, suggesting that the hydroxide functionality may facilitate the thermal decomposition. These insights enabled us to prepare size-and shape-controlled wz-CoO nanocrystals using purified [Co(OL)] 2 solutions, by incorporating additives that mimic the action of the hydroxide impurity. We also demonstrate a simplified pathway to wz-CoO nanocrystals that does not require chemical additives for thermolysis.
Facet-dependent catalytic activity of MnO electrocatalysts for oxygen reduction and oxygen evolution reactions
Kuo, Chung-Hao,Mosa, Islam M.,Thanneeru, Srinivas,Sharma, Vinit,Zhang, Lichun,Biswas, Sourav,Aindow, Mark,Pamir Alpay,Rusling, James F.,Suib, Steven L.,He, Jie
, p. 5951 - 5954 (2015)
This Communication highlights the facet-dependent electrocatalytic activity of MnO nanocrystals for OERs/ORRs. The MnO(100) facets with higher adsorption energy of O species can largely promote the electrocatalytic activity.
Size and doping effects on the improvement of the low-temperature magnetic properties of magnetically aligned cobalt ferrite nanoparticles
Knobel, Marcelo,Moscoso-Londo?o, Oscar,Muraca, Diego,Rivas-Rojas, Patricia C.,Socolovsky, Leandro M.,Tancredi, Pablo
, (2021/11/01)
The macroscopic magnetic behavior of nanoparticulated systems is the result of several contributions, ranging from the intrinsic structural properties of the nanoparticles to their spatial arrangement within the material. Unravelling and understanding these influences is an important task to produce nano-systems with improved properties for specific technological applications. In this work we study how the magnetic behavior of a set of magnetically hard nanoparticles can be improved by the modification of the sample arrangement (either randomly or magnetically oriented) and the nature of the enclosing matrices. At first, we employed a hot-injection, continuous growth strategy to synthesize non-stoichiometric cobalt ferrite (CoxFe3?xO4) nanoparticles. We prepared five batches of hydrophobic, oleate-coated samples, with mean diameters of 8 nm, 12 nm, 16 nm and variable Co-to-Fe proportions. The structural characterization confirms that the nanoparticles have a spinel-type monocrystalline structure and that the Co and Fe ions are homogenously distributed within the system. The magnetic properties of the nanoparticles were measured by DC magnetometry, and we found that the strategy used in this work to create a system of magnetically oriented nanoparticles can lead to a significant remanence and coercive field enhancement at low temperatures when compared with randomly oriented and fixed systems. The modification of the magnetic properties was detected in the five batches of samples, but the strength of the enhancement depends on both size and composition of the nanoparticles. Indeed, for the “hardest” samples the coercive field of the magnetically oriented systems reached values of around 30 kOe (3 T), which represents a 50% increase regarding the randomly oriented system and are among the highest reported to date for a set of Fe and Co oxide nanoparticles.
Rapid and large-scale synthesis of bare Co3O4 porous nanostructures from an oleate precursor as superior Li-ion anodes with long-cycle lives
Ge, Danhua,Wu, Junjie,Qu, Genlong,Deng, Yaoyao,Geng, Hongbo,Zheng, Junwei,Pan, Yue,Gu, Hongwei
, p. 13509 - 13513 (2016/09/04)
In this study, we describe a rapid and environmentally friendly synthesis of bare Co3O4 nanocrystals derived from Co(ii) oleate complexes by calcination treatment. When directly used as anode materials for lithium-ion batteries (LIBs), the as-prepared nanocrystals could deliver a high reversible capacity of 980 mA h g-1 after 250 cycles at a current density of 100 mA g-1 and excellent cycling performance, which may be beneficial to promote the further development of the next generation of lithium ion batteries. The synthetic route can offer great advantages for the flash preparation of other metal oxide nanocrystals for energy storage application.
