Zhensheng Hong(洪振生),* Kaiqiang Zhou(周凯强,硕士生), Junwen Zhang(张俊文,本科生), Zhigao Huang(黄志高) and Mingdeng Wei*, Facile synthesis of rutile TiO2 mesocrystals with enhanced sodium storage properties, Journal of Materials Chemistry A 3, 17412-17416 (2015).
Abstract
With the aim of developing high performance anode (negative) materials for sodium ion batteries (NIBs), rutile TiO2 with mesocrystalline structure were designed and used for enhancing the discharge capacity and reaction kinetics. The nanoporous rutile TiO2 mesocrystals constructed by crystallographically oriented nanoparticle subunits with tunable microstructures were successfully prepared via a facile synthesis route. Such rutile TiO2 architecture possesses a large surface area (157 m2 g-1), nanoporous nature and single-crystal-like structure, which could provide a high level of accessibility for the electrolyte and more active sites, and allow the fast electron and ion transport compared with the irregularly oriented nanoparticles. When evaluated as an anode material for sodium-ion storage, this unique architecture exhibited a high reversible capacity over 350 mA h g-1 at 50 mA g-1, superior rate capability with a stable capacity of 151 mA h g-1 at 2 A g-1 and good cycling stability.
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Journal of Materials Chemistry A 3, 17412-17416 (2015).pdf
Kaiqiang Zhou(周凯强,硕士生), Zhensheng Hong(洪振生)*, Chaobing Xie(谢超兵,本科生), Hong Dai, Zhigao Huang(黄志高)*, Mesoporous NiCo2O4 nanosheets with enhance sodium ion storage properties, Journal of Alloys and Compounds 651, 24-28 (2015).
Abstract
Two kinds of the NiCo2O4 nanosheets constructed by interconnected nanoparticles with different microstructures, including ultrathin NiCo2O4 nanosheets (NiCo2O4-UNSs) and common NiCo2O4 nanosheets (NiCo2O4-NSs), were controllably synthesized by a facile method. The structure and morphology of the NiCo2O4 nanosheets were analyzed and characterized by XRD, SEM and TEM. NiCo2O4-UNSs possess a large surface area (119 m2 g-1) and narrow pore distribution (around 5 nm). Subsequently, the Na-ion storage properties of such NiCo2O4 nanosheets were investigated by sodium half-cells. The ultrathin NiCo2O4 nanosheets (NiCo2O4-NSs) exhibit much improved performance than that of NiCo2O4-NSs with a high reversible capacity of 690.4 mA h g-1 at 100 mAg-1 and 141.8 mA h g-1 at the current density of 1000 mA g-1 in the voltage window of 0.01-2.5 V. Furthermore, a reversible capacity of about 203.7 mA h g-1 can be remained after 50 cycles at 200 mAg-1.
本网全文下载：Journal of Alloys and Compounds 651, 24-28 (2015).pdf
Lili Wang(王丽丽), Zhigao Huang(黄志高), Huiqin Zhang(张慧钦,硕士生), Ruibing Yu(余蕊冰,硕士生), Phase and magnetic properties evolutions of Y3−x(CaZr)xFe5−xO12 by the sol–gel method, Journal of Magnetism and Magnetic Materials 395, 73-80 (2015).
Abstract
In this work, Y3−x(CaZr)xFe5−xO12 (CaZr)x:YIG) were prepared by the sol–gel method. High substituted (CaZr)x:YIG nanoparticles with x up to 0.7 were obtained at 1080 °C, below the melting point of Cu electrode. The average sizes calculated by Scherrer formula decreased from 92.4 nm to 70.0 nm when the substitution amount increased from 0 to 0.7, which was consistent with the results of TEM. The sintering temperature required to form pure garnet phase increased from 690 °C to 1065 °C as the substitution amount x increased from 0 to 0.7 for probable homogeneity destruction by Ca2+ and Zr4+. The maximum saturation magnetization (Ms) of 29.8 emu/g was achieved at x=0.3. The enhancement of Ms was attributed to the quantity reduction of Fe3+ in a-site and the increase of net magnetic moment. The observed decline in Ms for the samples with x>0.3 might be attributed to the weakness of super-exchange interaction by changing the angle and length of Fe–O–Fe bonds too much. The complex variations of the coecivities (Hc) indicated the crystal structure from single domain to multiple domains as the sintering temperature increased. Comparing the properties of the samples with x=0 and 0.3, it seemed that the substitution had the influence not only on the formation temperature, but also on the critical size of single domain and the temperature of the critical size emerging.
本网全文下载：Journal of Magnetism and Magnetic Materials 395, 73-80 (2015).pdf
