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Abstract: P2-phase Na0.74CoO2 cathode material prepared by a solid-state method exhibits the specific discharge capacity of 107mAhg−1 at 0.1C with good cycling performance for rechargeable sodium ion batteries. The voltage polarization between charging and discharging at 0.1C rate is about 150–250mV and the coulombic efficiency in each cycle is about 89%. The expansion and compression in c-axis of the Na x CoO2 unit cell during the Na intercalation/deintercalation is revealed by ex situ XRD. XPS and in situ XAS data directly confirm that deintercalation/intercalation of Na ions from/into the layered structure proceeds with the Co3+/Co4+ redox reaction. [Copyright &y& Elsevier]

Abstract: Al-doped ZnO (ZnO:Al) thin films were deposited on Si substrates using the radio-frequency reactive magnetron sputtering technique. Effect of Al contents and annealing treatments on the structural and photoluminescence (PL) properties of ZnO films was investigated. The results showed that crystallinity of the films improved first with the increasing of Al content. However, as the Al content further increased more than 0.75wt %, the crystallinity was deteriorated. Meanwhile, the crystal quality of ZnO:Al thin films (Al content is 0.75wt %) was markedly improved after annealing at 600°C for 0.5h. Four main emission peaks located at 390, 445, 490 and 530nm were observed from PL spectra. As Al content was increased to 1.14wt %, the intensity of the blue peak (∼445nm) and the green peak (∼490nm) increased and the full width at half maxima (FWHM) decreased, and blue centre blue shifted to 429nm. A similar result can be obtained after annealing 600°C for 0.5h. This is attributed to Al doping and annealing treatment lead to the change of contents of antisite oxygen and interstitial Zn-related defects in the films. [Copyright &y& Elsevier]

Abstract: Pure and Al-doped ZnO (ZnO:Al) films have been deposited using radio frequency (RF) reactive magnetron sputtering at the O2:Ar ratio of 10:10, 6:10, and 2:10sccm and 150°C. The substrate temperatures were room temperature (RT), 150, 250, and 350°C and the O2:Ar ratio was 6:10sccm during the magnetron sputtering. The microstructures and optical properties in doped ZnO films were systematically investigated by X-ray diffraction (XRD) and fluorescence spectrophotometry. The results indicate that ZnO:Al films prepared at 250°C and 6:10sccm had the best crystal quality among all ZnO:Al films. Photoluminescence (PL) measurements at room temperature reveal a green and two blue emissions. The origin of these emissions is discussed. In addition, the intensity of blue emission peak first increased and then decreased as the substrate temperature shifted from RT to 350°C. The most intense blue luminescence was obtained from a sample grown at the O2:Ar ratio of 6:10sccm and 150°C. [Copyright &y& Elsevier]

Mn 3 O 4 /double-walled carbon nanotube nanocomposites for supercapacitor were successfully synthesized via a facile and low-cost chemical precipitation route, using potassium permanganate as precursor and hydrazine hydrate as reductant at room temperature. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier Transform infrared spectroscopy and Brunauer-Emmett-Teller surface area measurements, respectively. The Mn 3 O 4 nanoparticles were highly dispersed on the surface of double-walled carbon nanotubes. Cyclic voltammetry and galvanostatic charge/discharge technique were performed for the Mn 3 O 4 /double-walled carbon nanotube nanocomposites in 1 M Na 2 SO 4 aqueous solutions; the specific capacitance of Mn 3 O 4 /double-walled carbon nanotube nanocomposites (26.58 wt% Mn 3 O 4 ) was about 1080 Fg −1 at the current density of 15 Ag −1 with a long life time, owing to the high power density of Mn 3 O 4 nanoparticles and the large surface area, excellent catalysis, good conductivity, and high stability of the double-walled carbon nanotubes. [ABSTRACT FROM AUTHOR]