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Yang S.-Y.,Key Laboratory of Environmentally Friendly Chemistry | Wang X.-Y.,Key Laboratory of Environmentally Friendly Chemistry | Wang Y.,Wuhan Institute of Technology | Chen Q.-Q.,Key Laboratory of Environmentally Friendly Chemistry | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2010

Sodium manganese oxides, NaxMnO2+δ (x = 0.4, 0.5, 0.6, 0.7, 1.0; δ = 0-0.3), were synthesized by solid-state reaction routine combined with sol-gel process. The structure, morphology and electrochemical performances of as-prepared samples were characterized by XRD, SEM, CV, EIS and galvanostatic charge/discharge experiments. It is found that Na0.6MnO2+δ and Na0.7MnO 2+δ have high discharge capacity and good cycle performance. At a current density of 25 mA/g at the cutoff voltage of 2.0-4.3 V, Na 0.6MnO2+δ gives the second discharge capacity of 188 mA·h/g and remains 77.9 of second discharge capacity after 40 cycles. Na0.7MnO2+δ exhibits the second discharge capacity of 176 mA·h/g and shows better cyclic stability; the capacity retention after 40 cycles is close to 85.5. Even when the current density increases to 250 mA/g, the discharge capacity of Na0.7MnO2+δ still approaches to 107 mA·h/g after 40 cycles. © 2010 The Nonferrous Metals Society of China.

Zeng L.,Xiangtan University | Wang H.,Xiangtan University | Fu G.,Xiangtan University | Jiang J.,Xiangtan University | And 2 more authors.
Journal of Colloid and Interface Science | Year: 2010

A facile strategy for growing the comb-shaped poly (ε-caprolactone) brushes on the surface of nano-hydroxyapatite (n-HAP) by combination of atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP) would be presented. Firstly, ATRP was used to graft poly (2-hydroxyethyl methacrylate) (PHEMA) onto the n-HAP surface. Then, the hydroxyl groups introduced onto the n-HAP were used to initiate the ROP of ε-caprolactone for constructing comb-shaped polymer brushes on the surface of n-HAP. The surface modified n-HAP was characterized by Fourier transform infrared (FT-IR) spectra, 13C solid-state cross-polarization magic-angle-spinning (13C CP/MAS), and thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements, respectively. The results demonstrated that the comb-shaped poly (ε-caprolactone) brushes had been grafted successfully, and the grafting ratio could be controlled well by adjusting the feed ratio of initiator and monomer. © 2010 Elsevier Inc.

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