In situ and time resolved synchrotron X-ray diffraction investigation of solvothermal synthesis of mesoporous TiO2 beads

Mesoporous anatase (TiO2) beads are superior electrode materials for high performance dye-sensitized solar cells, producing greater than 10% solar to electric power conversion efficiency. Efficient solvothermal synthesis routes for mesoporous anatase beads may be developed by better understanding the reaction mechanism and kinetics. In this study, a series of in situ and time resolved X-ray diffraction (XRD) experiments have been conducted at the Australian Synchrotron. The solvothermal syntheses were conducted in quartz glass capillary microreactors while diffraction patterns were collected every 1-2 min. This allowed the induction period and the rate of crystallization from amorphous precursor to anatase to be determined for various synthesis conditions. This poster presentation describes the effects of time, temperature, precursor size and type (with or without hexadecylamine), and solution composition on the reaction kinetics, as well as on the domain size, size distribution, and morphology. Based on the kinetic evidence and post microscopic examination, we conclude that the synthesis follows a 3-dimensional bulk crystallization mechanism. The kinetics also shows promise for rapid and large scale production.