Mingdeng Wei

Utilization of Titanate Nanotubes as an Electrode Material in Dye-Sensitized Solar Cells

In this study, titanate H 2 Ti 3 O 7 nanotubes with a multiwall structure, synthesized by a hydrothermal process, were successfully used as an electrode material for dye-sensitized solar cells. The best efficiency, 7.5%, was achieved for an opened cell under illumination of simulated AM 1.5 solar light (100 mW cm -2 ). The relationship between the photovoltaic performance and physicochemical properties of titanate nanotube was also investigated.

Double perovskites containing hexavalent molybdenum and tungsten: synthesis, structural investigation and proposal of a fitness factor to discriminate the crystal symmetry

Double perovskites A II 2 B II B VI O 6 (A II =Ba, Sr, Ca; B II =Mg, Ni, Co, Cd, Ca; B VI =W, Mo, W 0.5 Mo 0.5 ) have been synthesized and their crystal structures investigated by powder X-ray diffraction measurements. In order to discriminate the crystal systems of the double perovskites, a fitness factor is proposed which corresponds to the size matching between the A cation and the cubo-octahedral cavity formed by eight BO 6 octahedrons. The fitness factor can discriminate the crystal systems of obtained compounds more exactly than the well known tolerance factor.

Fischer–Tropsch synthesis over cobalt catalysts supported on mesoporous alumino-silicate

Mesoporous alumino-silicate (MPAS) was prepared at ambient temperature by utilizing hexadecylpyridinium chloride as a surfactant, and used as the support of cobalt catalysts for Fischer–Tropsch synthesis in a slurry phase. The results of XRD and N2 adsorption measurements indicate that cations such as Co2+ and Ir4+ were effectively loaded on the surface of the mesopore walls, retaining mesoporous characteristics. The Co–Ir catalyst supported on MPAS showed excellent thermal stability, higher selectivity for C10–20 hydrocarbons and lower selectivity for CH4. These properties are affected by Al incorporated into the silica framework.

FISCHER-TROPSCH SYNTHESIS OVER COBALT CATALYSTS SUPPORTED ON MODIFIED SiO2 WITH MESOPOROUS SILICA

SiO2 was modified by hexagonal mesoporous silica to form a mixture with meso-/macroporous sizes and used as support of Co catalysts for Fischer-Tropsch synthesis in a slurry phase. A synergistic effect on the activity of Co catalyst was found. The catalytic properties are related to the state of surface Co and the character of support.

Mesoporous metallo-silicates as a support of cobalt catalysts for slurry phase Fischer¿Tropsch synthesis

A series of mesoporous metallo-silicates (M-MPS, M = Al, Mn, V, Zr, and Mo) was synthesized at ambient temperature by utilizing hexadecylpyridinium chloride as a surfactant and was used as the support of cobalt catalysts for Fischer–Tropsch synthesis in a slurry phase. The catalysts supported on M-MPS showed a higher selectivity for C5+ hydrocarbons and had a higher chain growth probability α, as well as a lower selectivity for CH4. A good correlation between the selectivity for CH4 and the standard enthalpy of formation of metal oxides incorporated into the silica framework, –ΔH0f, was obtained and the role of metals incorporated into the silica framework in Fischer–Tropsch synthesis is discussed.