Enhanced photoelectrochemical activities of a nanocomposite film with a bamboo leaf-like structured TiO(2) layer on TiO(2) nanotube arrays

A novel nanocomposite TiO(2) film consisting of a bamboo leaf-like nano TiO(2) layer on a nanotubular TiO(2) arrays surface is synthesized by electrochemical anodization with wet chemical pretreatment; it shows almost three times higher activity as compared to that of nanotubular TiO(2) arrays alone.National Natural Science Foundation of China[51072170, 20773100, 20620130427]; National Basic Research Program of China[2007CB935603]; National High Technology Research and Development Program of China[2009AA03Z327

Semiconductor hierarchically structured flower-like clusters for dye-sensitized solar cells with nearly 100% charge collection efficiency

Georgia Institute of TechnologyBy combining the ease of producing ZnO nanoflowers with the advantageous chemical stability of TiO2, hierarchically structured hollow TiO2 flower-like clusters were yielded via chemical bath deposition (CBD) of ZnO nanoflowers, followed by their conversion into TiO2 flower-like clusters in the presence of TiO2 precursors. The effects of ZnO precursor concentration, precursor amount, and reaction time on the formation of ZnO nanoflowers were systematically explored. Dye-sensitized solar cells fabricated by utilizing these hierarchically structured ZnO and TiO2 flower clusters exhibited a power conversion efficiency of 1.16% and 2.73%, respectively, under 100 mW cm(-2) illumination. The intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) studies suggested that flower-like structures had a fast electron transit time and their charge collection efficiency was nearly 100%

Facile and effective synthesis of hierarchical TiO2 spheres for efficient dye-sensitized solar cells

National Natural Science Foundation of China [51072170, 21021002]; National Basic Research Program of China [2012CB932900]Three-dimensional (3D) crystalline anatase TiO2 hierarchical spheres were successfully derived from Ti foils via a fast, template-free, low-temperature hydrothermal route followed by a calcination post-treatment. These dandelion-like TiO2 spheres are composed of numerous ultrathin nanoribbons, which were subsequently split into fragile nanoflakes as a result of the decomposition of Ti-complex intermediates to TiO2 and H2O at high temperature. The dye-sensitized solar cells (DSSCs) employing such hierarchically structured TiO2 spheres as the photoanodes exhibited a light-to-electricity conversion efficiency of 8.50%, yielding a 28% enhancement in comparison with that (6.64%) of P25-based DSSCs, which mainly benefited from the enhanced capacity of dye loading in combination with effective light scattering and trapping from hierarchical architecture

Garden-like perovskite superstructures with enhanced photocatalytic activity

Chinese Scholarship Council; National Natural Science Foundation of China [51072170, 21021002]; National Basic Research Program of China [2012CB932900]; Minjiang Scholar Program and Georgia Institute of TechnologyBy subjecting amorphous flower-like TiO2 to a facile hydrothermal synthesis in the presence of Sr2+, garden-like perovskite SrTiO3 superstructures were achieved. The amorphous TiO2 was preformed using ZnO flowers as templates. Different three-dimensional SrTiO3 architectures were coexisted in the garden, including SrTiO3 flowers composed of several hollow sword-shaped petals, many sheet-shaped petals or numerous flake-shaped petals, and SrTiO3 grass consisting of a number of long blades. These SrTiO3 superstructures were simultaneously grown on fluorine-doped tin oxide (FTO) substrates. On the basis of a comprehensive study on the effects of growth time, temperature, initial concentrations of precursor, and pH, the formation of these various hierarchical architectures was attributed primarily to the dissolution of amorphous TiO2 and precipitation of perovskite crystals, followed by the Ostwald ripening process of perovskite nanocrystals and self-organization of perovskite building blocks. Interestingly, this approach can be readily extended to create other perovskite structures, including dendritic BaTiO3 and nest-like CaTiO3, as well as PbTiO3 transformed from plate-like pyrochlore Pb2Ti2O6 after post-thermal treatment. Garden-like SrTiO3 superstructures showed a superior photocatalytic performance when compared to other as-prepared semiconductors and perovskite materials (i.e., ZnO, TiO2, BaTiO3, CaTiO3 and PbTiO3), probably due to their intrinsic photocatalytic activity and special garden-like features with a coexistence of various structures that significantly facilitated the adsorption and diffusion of methyl blue (MB) molecules and oxygen species in the photochemical reaction of MB degradation

Surface-Treated TiO2 Nanoparticles for Dye-Sensitized Solar Cells with Remarkably Enhanced Performance

DOE Ames Lab through the Science Undergraduate Laboratory Internships (SULI); Georgia Institute of TechnologyDye-sensitized solar cells (DSSCs) were prepared by capitalizing on mesoporous P-25 TiO2 nanoparticle film sensitized with N719 dyes. Subjecting TiO2 nanoparticle films to TiCl4 treatment, the device performance was improved. More importantly, O-2 plasma processing of TiO2 film that was not previously TiCl4-treated resulted in a lower efficiency; by contrast, subsequent O-2 plasma exposure after TiCl4 treatment markedly enhanced the power conversion efficiency, PCE, of DSSCs. Remarkably, with TiCl4 and O-2 plasma treatments dye-sensitized TiO2 nanoparticle solar cells produced with 21 mu m thick TiO2 film illuminated under 100 mW/cm(2) exhibited a PCE as high as 8.35%, twice of untreated cells of 3.86%