Nitrogen-doped hollow carbon spheres with tunable shell thickness for high-performance supercapacitors.

Nitrogen-doped hollow carbon spheres (NHCSs) are well prepared by using Cu2O microspheres as a hard template and 3-aminophenol formaldehyde resin polymer as carbon and nitrogen precursors. The thickness of the carbon shell can be easily controlled in the range of 15-84 nm by simply adjusting the weight ratios of the precursors to Cu2O microspheres, and the Cu2O templates can also be further reused. Physicochemical characterization demonstrates that the obtained NHCSs possess a well-developed hollow spherical structure, thin carbon shell and high nitrogen doping content. Due to these characteristics, when further utilized as electrodes for supercapacitors, the NHCSs with the carbon shell thickness of 15 nm show a high capacitance of 263.6 F g-1 at 0.5 A g-1, an outstanding rate performance of 122 F g-1 at 20 A g-1 and an excellent long-term cycling stability with only 9.8% loss after 1000 cycles at 5 A g-1 in 6 M KOH aqueous electrolyte. This finding may push forward the development of carbon materials, exhibiting huge potential for electrochemical energy storage applications.

Three-dimensional low symmetry mesoporous silica structures templated from tetra-headgroup rigid bolaform quaternary ammonium surfactant.

Two kinds of highly ordered mesoporous silica materials (FDU-11, FDU-13) with novel three-dimensional (3-D) tetragonal and orthorhombic structures were synthesized by using tetra-headgroup rigid bolaform quaternary ammonium surfactant [(CH(3))(3)NCH(2)CH(2)CH(2)N(CH(3))(2)CH(2)(CH(2))(11)OC(6)H(4)C(6)H(4)O(CH(2))(11)CH(2)N(CH(3))(2)CH(2)CH(2)CH(2)N(CH(3))(3).4Br] (C(3-12-12)(-)(3)) as a template under alkaline conditions. High-resolution transmission electron microscopy (HRTEM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD) show that mesoporous silica FDU-11 has primitive tetragonal P4/mmm structure with cell parameters a = b = 8.46 nm, c = 5.22 nm, and c/a ratio = 0.617. N(2) sorption isotherms show that calcined FDU-11 has a high BET surface area of approximately 1490 m(2)/g, a uniform pore size of approximately 2.72 nm, and a pore volume of approximately 1.88 cm(3)/g. Mesoporous silica FDU-13 has primitive orthorhombic Pmmm structure. The cell parameters are a = 9.81, b = 5.67, and c = 3.66 nm. N(2) sorption isotherms show that calcined FDU-13 has a high BET surface area of 1210 m(2)/g, a uniform mesopore size of approximately 1.76 nm, and a large pore volume of approximately 1.83 cm(3)/g. Such low symmetries for 3-D mesostructures (tetragonal and orthorhombic system) have not been observed before even in amphiphilic liquid crystals, which maybe resulted from an oblate aggregation of the bolaform surfactant and its strong electrostatic interaction with inorganic precursor. A probable mechanism has been proposed for the formation of such a 3-D low symmetrical mesostructure. These results will further extend the synthesis of mesoporous materials and may open up new opportunities for their new applications in catalysis, separation, and nanoscience.

A novel ordered cubic mesoporous silica templated with tri-head group quaternary ammonium surfactant.

An ordered mesoporous silica with novel cubic structure (space group Fd3m) has been synthesized by using tri-head group quaternary ammonium surfactants [CmH2m + 1N+(CH3)2CH2CH2N+(CH3)2CH2CH2CH2N+(-)(CH3)(3).3Br-] (Cm-2-3-1, m = 14, 16, 18) as the structure-directing agents under basic conditions at low temperature.