Browsing by Author "Cheng, YB"

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    Synthesis of monodisperse mesoporous titania beads with controllable diameter, high surface areas, and variable pore diameters (14−23 nm)
    (American Chemical Society, 2010-03-31) Chen, DH; Cao, L; Huang, FZ; Imperia, P; Cheng, YB; Caruso, RA
    Monodisperse mesoporous anatase titania beads with high surface areas and tunable pore size and grain diameter have been prepared through a combined sol−gel and solvothermal process in the presence of hexadecylamine (HDA) as a structure-directing agent. The monodispersity of the resultant titania beads, along with the spherical shape, can be controlled by varying the amount of structure-directing agent involved in the sol−gel process. The diameter of the titania beads is tunable from 320 to 1150 nm by altering the hydrolysis and condensation rates of the titanium alkoxide. The crystallite size, specific surface area (from 89 to 120 m2/g), and pore size distribution (from 14 to 23 nm) of the resultant materials can be varied through a mild solvothermal treatment in the presence of varied amounts of ammonia. On the basis of the results of small-angle XRD, high-resolution SEM/TEM, and gas sorption characterization, a mechanism for the formation of the monodisperse precursor beads has been proposed to illustrate the role of HDA in determining the morphology and monodispersity during the sol−gel synthesis. The approach presented in this study demonstrates that simultaneous control of the physical properties, including specific surface area, mesoporosity, crystallinity, morphology, and monodispersity, of the titania materials can be achieved by a facile sol−gel synthesis and solvothermal process. © 2010, American Chemical Society
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    Zn-doped TiO2 electrodes in dye-sensitized solar cells for enhanced photocurrent
    (Royal Society of Chemistry, 2012-07-20) Huang, FZ; Li, Q; Thorogood, GJ; Cheng, YB; Caruso, RA
    Porous nanocrystalline Zn/TiO2 materials were synthesized employing agarose gel as a template, achieving a maximum Zn-doping concentration of around 2 at.%. Low Zn-doping concentrations (e.g. <1 at.%) improved the photocurrent of the dye-sensitized solar cell when these materials were applied as the working electrode, as n-type doping favors electron transportation. Compared to the efficiency of the undoped sample, 6.7%, the 0.5 at.% sample showed a much higher efficiency of 7.6%. Further doping decreases the performance of the device as it introduces deficiencies that act as electron–hole recombination centers. © 2012 The Royal Society of Chemistry