The Preparation And Photoelectric Performance Of Hierarchical Titanium Dioxide Nanoflowers

Since the 1970s,due to its low cost,high stability,simple process,controllable morphology,and non-toxicity,TiO₂ has been widely used in dye-sensitized solar cells and photocatalysis.A large number of studies have proved that the crystal shape,morphology,size and crystallinity of TiO₂ have important influence on its performance.In this paper,a hierarchical TiO₂ nanoflower?HTF?structure with large size and large specific surface area was designed and synthesized prepared by a simple hydrothermal method consisting of self-assembly ultrathin TiO₂ nanosheets.With its size effect,surface area effect and ultrathin properties,HTF is applied to dye-sensitized solar cells and photocatalytic water.The research contents and results are as follows:?1?The application and performance of HTF in photoanode for dye-sensitized solar cellsBy adjusting the ratios of HTF and anatase TiO₂ nanoparticles?TNP?in dye-sensitized solar cells,the differences of optical,electrical,and efficiency of dye-sensitized solar cells with photoanodes prepared by different ratio of HFT were studied,and explore the possible mechanism of different content of HTF in photoanode in dye-sensitized solar cells.The results show that the photoelectric conversion efficiency of HTF10/N719 battery reaches to 6.4%.Compared to the conventional TiO₂ nanoparticles,the photoelectric conversion efficiency of4.2%was improved by 52.2%.This excellent performance is attributed to the fact that HTF not only enhances light scattering and improves light utilization but also provides more sites for dye adsorption,thereby obtaining more photoelectrons and effectively improving the light conversion efficiency of the battery.?2?Application and properties of composite photocatalyst consist of HTF in hydrogen productionTwo-step photoreduction deposition method was used to deposit Pt metal nanoparticles and CdS on the surface of synthesized HTF to form three-component photocatalysts,namely HTF/Pt/CdS.The properties of photocatalytic hydrogen evolution of HTF/Pt/CdS under light irradiation were investigated.By the analysis of the microstructure of the three-component composite photocatalyst and the study of the photoelectric properties,the main reasons for the improvement of the efficiency of hydrogen production by photolysis of water using ternary composites were described as below.Firstly,the narrow bandgap semiconductor CdS has a photoresponse to visible light and can expand the absorption range of sunlight.This compensates for the inadequacy of TiO₂ being able to absorb UV light only and enhances the utilization of sunlight.Secondly,HTF prepared by hydrothermal method has the characteristic of large specific surface area,which provides more sites for loading of CdS and facilitates the deposition of more CdS.And more CdS means that it can absorb more sunlight and generate more photogenerated carriers.At the same time,HTF has an ultra-thin TiO₂ nanosheet structure.The ultra-thin nanosheet structure facilitates the rapid transfer of photogenerated carriers and holes to the surface,thereby reducing the recombination effect of photogenerated carriers and holes.In addition,due to the Z-scheme structure of HTF/Pt/CdS catalysts,photocarriers on the TiO₂ conduction band and holes on the valence band of CdS can be rapidly injected on the Pt surface for combination,leaving photo Carriers in CdS conduction band and vacancies in the valence band of TiO₂,which promote the separation of photogenerated carriers and give higher energy electrons.