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Growing MnO 2 nanofibers on graphitic hollow carbon spheres (GHCS) is conducted by refluxing GHCS in a KMnO 4 aqueous solution aimed to enhance the electrochemically active surface area of MnO 2 . The stoichiometric redox reaction between GHCS and MnO 4À yields GHCS-MnO 2 composites with controllable MnO 2 content. It is found that these ultrathin MnO 2 nanofibers are vertically grown on the external surface of the GHCS, yielding a composite electrode showing good electron transport, rapid ion penetration, fast and reversible Faradic reaction, and excellent rate performance when used as supercapacitor electrode materials. An asymmetric supercapacitor cell with GHCS-MnO 2 as the positive electrode and GHCS as the negative electrode can be reversibly charged/discharged at a cell voltage of 2.0 V in a 1.0 mol L À1 Na 2 SO 4 aqueous electrolyte, delivering an energy density of 22.1 Wh kg À1 and a power density of 7.0 kW kg À1 . The asymmetric supercapacitor exhibits an excellent electrochemical cycling stability with 99% initial capacitance and 90% coulombic efficiency remained after 1000 continuous cycles measured using the galvanostatic charge-discharge technique.

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A novel ZnIn 2 S 4 catalyst synthesized by hydrothermal method shows high and stable photocatalytic activity for water reduction under visible light illumination.In recent years photocatalytic water splitting using solar energy has received a great deal of attention because of the global energy and environmental problems. During the past decades many mixed oxide photocatalysts such as SrTiO 3 , 1 KNb 6 O 17 2 and NaTaO 3 3 have been reported to show high activity for overall water splitting. These photocatalysts, however, are effective only in the ultraviolet region due to their wide band gap. In order to improve the efficiency of utilizing the solar energy, the development of visible-light-driven photocatalysts for water splitting is indispensable. Unfortunately, the number of photocatalysts working under visible light irradiation is still limited. [4][5][6] In contrast to the metal oxide photocatalysts, many metal sulfides have the narrower band gaps that correspond to the visible light absorption. 7 The ternary sulfides with strong absorption in the visible region may be good candidates for photocatalytic water splitting to produce hydrogen. But, it is commonly believed that metal sulfides are unstable during the photocatalytic reaction. Improving the stability of metal sulfide catalyst such as CdS for water splitting is challenging. A few efforts have been made, for example, by incorporating the nanoparticles of metal sulfide into the interlayer 8 or mesoporous silica 9 to stabilize the metal sulfides. The preparation procedure is complicated and the photocatalytic efficiency is still very low. It has recently been reported that multicomponent metal sulfide 7 and oxysulfide 4 show stable photocatalytic activity for water reduction and oxidation. These results imply that the multicomponent metal sulfide could be a new class of stable photocatalyst for water reduction.Zinc indium sulfide, ZnIn 2 S 4 , is a ternary chalcogenide which belongs to the family of ternary compound AB 2 X 4 . ZnIn 2 S 4 is a potential photoconducting material 10 and has been extensively applied to the electrochemical recording and photovariable capacitor. But, there is no report on the photocatalytic water reduction over the ternary compound of AB 2 X 4 . These compounds are conventionally prepared by the chemical transport method. 11 This method usually requires high temperature and high vacuum, as well as a transporting agent such as iodine. In this communication, we report a chemically stable ZnIn 2 S 4 photocatalyst prepared by a direct hydrothermal synthesis method. UV-visible diffuse reflectance spectra shows that the absorption edge of ZnIn 2 S 4 is in the visible region, corresponding to the band gap of 2.3 eV. It is found that the ZnIn 2 S 4 shows high activity for photocatalytic water reduction under visible light (l > 420 nm) irradiation. More interestingly, the H 2 evolution rate gradually increases with prolonged photocatalytic reaction time. No deactivation is observed even after photocatalytic reaction for 150 h.The ZnS...

Hierarchical graphene-based composite consisting of graphene sheets intercalated by MnO(2)-coated carbon nanotubes (MnC) was prepared for high-performance supercapacitor electrode. The highly negatively charged graphene oxides reduced by urea (RGO) and the positively charged MnC functionalized with poly(diallyldimethylammonium chloride) created a strong electrostatic interaction, forming a hierarchical nanostructure. The elelctrocapacitive behaviors of MnC/RGO (MnC-G) were systematically investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 193 F/g was achieved for the MnC-G composite with 37% RGO, which was almost 3-fold higher than 69 F/g of carbon nanotubes/RGO and 2-fold higher than 89 F/g of MnO(2)/RGO composite. Moreover, an excellent rate performance, a good capacitance retention (~70%) and a superior Coulombic efficiency (94-96%) were also observed during the continuous 1300 cycles of galvanostatic charge-discharge.

Anisotropic 2D layered material rhenium disulfide (ReS2 ) with high crystal quality and uniform monolayer thickness is synthesized by using tellurium-assisted epitaxial growth on mica substrate. Benefit from the lower eutectic temperature of rhenium-tellurium binary eutectic, ReS2 can grow from rhenium (melting point at 3180 °C) and sulfur precursors in the temperature range of 460-900 °C with high efficiency.

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