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Understanding solvothermal crystallization of Mesoporous Anatase Beads by in situ synchrotron PXRD and SAXS
Journal article   Peer reviewed

Understanding solvothermal crystallization of Mesoporous Anatase Beads by in situ synchrotron PXRD and SAXS

F. Xia, D. Chen, N.V.Y. Scarlett, I.C. Madsen, D. Lau, M. Leoni, J. Ilavsky, H.E.A. Brand and R.A. Caruso
Chemistry of Materials, Vol.26(15), pp.4563-4571
2014
DOI: https://doi.org/10.1021/cm501810x
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Abstract

Submicrometer-sized mesoporous anatase (TiO2) beads have shown high efficiency as electrodes for dye-sensitized solar cells and are recoverable photocatalysts for the degradation of organic pollutants. The detailed mechanism for crystallization of the amorphous TiO2/hexadecylamine (HDA) hybrid beads occurring during the solvothermal process needs to be understood so that reaction parameters can be rationally refined for optimizing the synthesis. In this work, the solvothermal crystallization was monitored by in situ synchrotron powder X-ray diffraction (PXRD) and synchrotron small-angle X-ray scattering (SAXS) techniques. In situ PXRD provided crystallization curves, as well as the time evolution of anatase crystallite mean size and size distribution, and in situ SAXS provided complementary information regarding the evolution of the internal bead structure and the formation of pores during the course of the solvothermal process. By exploring the effects of temperature (140–180 °C), bead diameter (300 and 1150 nm), bead internal structure, and solvent composition (ethanol and ammonia concentrations) on this process, the crystallization was observed to progress 3-dimensionally throughout the entire bead due to solvent entrance after an initial fast partial dissolution of HDA from the nonporous precursor bead. On the basis of the kinetic and size evolution results, a 4-step crystallization process was proposed: (1) an induction period for precursor partial dissolution and anatase nucleation; (2) continued precursor dissolution accompanied by anatase nucleation and crystal growth; (3) continued precursor dissolution accompanied by only anatase crystal growth; and (4) complete crystallization with no significant Ostwald ripening.

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Collaboration types
Domestic collaboration
International collaboration
Citation topics
2 Chemistry
2.74 Photocatalysts
2.74.5 TiO2 Photocatalysis
Web Of Science research areas
Chemistry, Physical
Materials Science, Multidisciplinary
ESI research areas
Materials Science
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