No abstract

No abstract

A facile solvothermal process combined with a precursor thermal transformation method has been developed for preparing porous TiO 2 hollow nanospheres with a high surface area and a good thermal stability. The porous TiO 2 hollow spheres were obtained by using TiOSO 4 as a titanium source and carbon nanospheres as a sacrificial template. Their particle size, diameter and morphology can be readily controlled by varying growth parameters, including reaction temperature, time and reagent concentration. The calcination temperature of TiO 2 -C core-shell nanospheres was found to have a profound effect on the structure and properties of the final products. The photocatalytic activities of the products were evaluated by the photodegradation of methyl orange (MO). The TiO 2 hollow spheres obtained from 450 C thermal treatment exhibited higher photocatalytic activity than commercial Degussa P25 in the presence of Cr(VI). The possible photodegradation mechanism was also investigated.

Three-dimensional (3D) interconnected spherical graphene framework-decorated SnS nanoparticles (3D SnS@SG) is synthesized by self-assembly of graphene oxide nanosheets and positively charged polystyrene/SnO nanospheres, followed by a controllable in situ sulfidation reaction during calcination. The SnS nanoparticles with diameters of ∼10-30 nm are anchored to the surface of the spherical graphene wall tightly and uniformly. Benefiting from the 3D interconnected spherical graphene framework and subtle SnS nanoparticles, the generated LiS could keep in close contact with Sn to make possible the in situ conversion reaction SnS + 2Li + 2e ↔ Sn + LiS. As a result, the 3D SnS@SG as the anode material for lithium ion batteries shows a high initial Coulombic efficiency of 75.3%. Apart from the irreversible capacity loss of 3D spherical graphene, the initial Coulombic efficiency of SnS in the 3D SnS@SG composite is as high as 99.7%, demonstrating the almost complete reversibility of LiS in this system. Furthermore, it also exhibits an excellent reversible capacity (800 mAh g after 100 cycles at 0.1 C and 527.1 mAh g after 300 cycles at 1 °C) and outstanding rate capability (380 mAh g at 5 °C).

No abstract