In this paper, we report a novel and simple method for synthesizing the microspheres self-assembled from ultrathin anatase TiO2nanosheets with a high percentage of (001) facets via the hydrolysis process of the single-reagent (potassium fluorotitanate). We then used optical microscopy, scanning electron microscopy, and high-resolution confocal laser Raman spectroscopy to characterize the microspheres generated under different conditions. The study found that the size of the anatase TiO2microspheres synthesized was 0.5–3 μm. As the synthesis time increased, the corroded surface of the microspheres gradually increased, resulting in the gradual disappearance of the edges and corners of the anatase nanosheets. The exposure percentage of the (001) facets of ultrathin anatase nanosheets synthesized for 2 h at 180–200 °C are close to 100%. The microsphere whose surface is completely covered by these anatase nanosheets also has nearly 100% exposed (001) facets. This new anatase nanosheet-based self-assembled microsphere will have great application potential in pollution prevention, environmental protection, and energy fields.
Hong Tao,Wanping Chen,Jing Wang,Weijun Ke,Jiawei Wan,Jionghua Wu,Guo-jia Fang
Size controllable anatase TiO 2 microspheres with compact nano-aggregate structures are synthesized via a facile and low-temperature solvothermal treatment. The diameters of as-prepared products can be controlled to vary from 250 to 1100 nm. Different kinds of TiO 2 microsphere films are built on the top of TiO 2 nanoparticle underlayer to prepare a type of bi-layer anodes. It is illustrated that this type of TiO 2 microsphere scattering layer can not only increase the absorption of light, but also improve the carrier transport and charge collection efficiency of dye sensitized solar cell (DSSC). Therefore, an optimized efficiency of 8.20% is achieved for DSSC with a scattering layer consisted of 500 nm TiO 2 microspheres. Then we further optimize the interface of TiO 2 microsphere scattering layer through TiCl 4 treatment and Mg 2+ modified TiCl 4 treatment. TiCl 4 treatment can improve the dye adsorption and connections between the TiO 2 microspheres. However, it also generates more surface defects in the meantime. And through the Mg 2+ modified TiCl 4 treatment, we can increase the dye adsorption density and retard the interfacial charge recombination and decrease the surface defects, simultaneously. As a result, the efficiency of DSSC based on bi-layer anode is enhanced from 8.20% to 9.12%.
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