| There are many disadvantages of traditional titania photocatalyst, such as low quantum efficiency, uncontrollable granule morphology and low utilization efficiency of sunlight. Focused on these problems, three different routes were used: the hydrothermal process with PEG assisted, the hydrothermal reaction-thermolysis process and one-step hydrothermal process in the presence of different amines. Synthesized titania are of broad-spectrum, high efficiency and wideband-response. They were characterized by XRD, TEM, SEM, XPS, UV-Vis DRS, TG-DTA, FTIR and N2 adsorption-desorption. With the solution of X-3B as target pollutants, photocatalytic activity of synthesized photocatalysts were evaluated under UV-light, visible-light and UV-visible Wideband light. The results of crystal phases, granule morphology, particle size and UV-visible absorption spectra of products were correlated with their photocatalytic activities. The main factor that affected photocatalytic activities was obtained. The contents of this paper were divided into three sections.In the first,section, anatase titania nanocrystals with controllable morphorlogy and size were synthesized by the hydrothermal process with PEG assisted and cheap titanium sulfate as Ti source. By varying PEG concentration from 0 to 0.16 g·mL-1, rod-like and global nanopowders with uniform distribution were prepared. Obtained products have tunable granule size and show typical worm-like mesoporous structure. Under optimum condition, large BET surface area (265 m2·g-1) was obtained. The UV-light Photocatalytic degradation with the degradation for X-3B solution as a probe reaction demonstrates that, after irradiation for 1 h, the removal rate reached 40 % compared to no PEG assisted product. The results provided a simple and efficient route for synchro controlling modality, morphology, crystal phase, size and surface texturing of titania nanocrystals.In the second section, visible-light-response of N-doped titania nanocrystals were synthesized by the hydrothermal reaction-thermolysis process using ammonia as N source. The results show that the modality of precursors before calcination was correlative greatly with hydrothermal temperature. The formation of layered ammonium titanate synthesized oniy at 150°C was the key process for obtaining highly active photocatalysts. The precursor not only has developed microporous-mesoporous structure, but also possesses double functions: "nitrogen fixation" which can avoid the loss of N element and crystallization inducement in the thermolysis process. The absorption band of synthesized products shifted from 387 nm before N-doping to 550 nm after N-doping, the main reason may be that the oxygen vacancy structure narrowed the band-gap. The N-doped method mentioned in this paper is simple and efficient.In the third section, different amines such as methylamine, ethylamine and diethylamine were induced to reaction system. Anatase N-doped titania nanocrystals were successfully synthesized by the one-step hydrothermal process under soft chemical conditions of low temperature and short time (150℃, 8 h). Thus, the calcination process at high temperature was avoided effectively. The results show that, the synthesized system with diethylamine as N source is the optimal nitrogen-doped condition, under which obtained products not only have perfect crystallity and regular morphology but also possess broad-spectrum response. Synthesized N-doped products are novel and high-efficient photocatalysts which can respond visible light and UV-visible Wideband light. The results provided new theoretic evidence for exploring new N-doped process and broad-spectrum and high-efficient use of sunlight.
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