Mixed Solvents Assisted Flame Spray Pyrolysis Synthesis of TiO₂ Hierarchically Porous Hollow Spheres for Dye-Sensitized Solar Cells

Abstract

A novel one-step and template-free preparation process had been developed to synthesize TiO 2 hierarchically porous hollow spheres (HPHSs) by mixed solvents assisted flame spray pyrolysis (FSP). The as-obtained TiO 2 HPHSs had hierarchically porous hollow structure such as central cavities, macropores on shells, and mesopores accumulated by TiO 2 nanocrystallites. The unique hierarchically porous structure endowed the TiO 2 spheres with high specific surface area and excellent light scattering property. A mechanism of the formation of TiO 2 HPHSs depending on the competition between chemical reaction rate and diffusion rate of the components of the precursor was proposed, in which mixed solvents and short flame residence time were of importance. Furthermore, the dye-sensitized solar cells (DSSCs) performance of TiO 2 HPHSs as light scattering layer was investigated. The photoelectric conversion efficiency (η) was improved by 38.2% (from 5.00% to 6.91%), comparing to that of single layer P25 films.

Synthesis and applications of porous non-silica metal oxide submicrospheres

“…16. There are numerous reports on the use of TiO 2 particles of varying architecture in DSSCs such as spheres, 184,190,192,195,217,245,[288][289][290] hollow spheres, 227,248,291 and yolk-shell structures. 208 Macroporous TiO 2 spheres were prepared by an emulsion templating method using PS particles as templates for the macropores, 184 and were formed via calcination of the PS-TiO 2 composite spheres.…”

Nanostructured Semiconductor Materials for Dye-Sensitized Solar Cells

“…Ohtani et al clarified that the photocatalytic activity of TiO 2 powders strongly depends on its physical properties such as crystal structure, surface area, particle size, and surface hydroxyls [41]. In literature, a variety of preparation techniques, such as sol-gel [42], hydrothermal/solvothermal [43,44], electrochemical anodization [45], electrospinning [46,47], spray pyrolysis [48], and atomic layer deposition [49], have been developed and applied to obtain different morphologies in photoanode materials. Asim et al summarized the different preparation and deposition methods, which have been used for photoanode materials of DSSCs, emphasizing their advantages and disadvantages, in order to allow a researcher to carefully choose and optimize a given method [50].…”

Hollow spherical titanium dioxide nanoparticles for energy and environmental applications

“…Hollow spherical TiO 2 nanoparticles have been used as electrode materials, and the resulting DSSCs exhibited higher performance than those containing mesoporous TiO 2 . This is because the TiO 2 hollow spheres provided a larger surface area for dye loading, light scattering, and charge collection (Dai et al, 2012;Huo et al, 2013;Lin, Song, Gu, Zhao, & Qiang, 2012;Zhao et al, 2014).…”