| With the emergence of environmental pollution and energy crisis, photocatalysis technology has attracted vast attention in scientific community owing to its potential application in environmental purification and new energy development. Expanding the application of photocatalysis consists in the synthesis of photocatalysts as well as the exploration of implementing photocatalysis. The crux of the matter is to develop method for preparing highly active photocatalysts with strong practicability. This thesis focused on the liquid-phase fabrication of photocatalytic films composed of low-dimensional nanomaterials. The effects of the various nanostructures on the catalytic performance of these films were examined in detail. The application of the nanostructured photocatalytic films in fields of self-cleaning surface, environmental purification, and water quality assessment was also systematically investigated.Rutile TiO2nanorod arrays were grown on fluorine-doped tin oxide (FTO) covered glass substrate and bare glass substrate through simple hydrothermal and solvothermal processes, respectively. The compact FTO nanoparticles on the substrate have similar crystal lattice in size to that of the rutile TiO2, which plays an important role in TiO2nucleus formation and vertical growth. The FTO nanoparticles range from100nm to200nm, and just tally with the diameters of the TiO2nanorods grow on FTO substrate. This suggests the small lattice mismatch between the FTO and rutile TiO2may promote the epitaxial nucleation and growth of rutile TiO2on FTO substrate. Vertically ordered TiO2nanorods were not obtained for bare glass substrate by hydrothermal method, except for fascicularly distributed TiO2nanorods with much bigger diameters. The addition of ethanol or ethylene glycol to the reaction system made it possible to control the morphology and structure of the TiO2nanorods. With the addition of ethanol, the diameters of the nanorods had a sharp drcrease, while the fascicular growth was enhanced. A coordination effect was created when ethylene glycol was added to the solvent. Ethylene glycol served as a ligand to form chain-like coordination complexes with TiO6octahedron, which induced vertical growth of the TiO2nanorods with smaller diameters on bare glass substrate. The vertically ordered TiO2nanorod arrays on bare glass substrate allowed70%transmittance for light with wavelength above520nm and had excellent properties in hydrophobic and photocatalytic self-cleaning performance. The water contact angle could reach118°, and the organic contaminants could be degraded in several minutes under UV light.Three ways were used to oxidize Ti foil for fabricating various nanostructured films composed of one-dimensional TiO2nanomaterials, including nanorods, nano fibers and nanotubes. Detection of organic concentration was carried out based on the photoelectrocatalysis of these films. Firstly, the Ti foil was oxidized in H2O2solution, and formation of vertically ordered TiO2nanorod arrays could be achieved at80℃. Thermal treatment at300℃resulted in the mixture of anatase and rutile nanorods. The rutile content gradually increased with the rise of the temperature, and the photocurrent also increased while the increasing rate was gradually depressed. This indicates that the mixed crystal effect promotes the photocatalytic efficiency by retarding the recombination of photogenerated electrons and holes, but the decrement of the specific surface stemed from thermal treatment at higher temperature counteracts the effect. Secondly, hydrothermal and solvothermal processes were employed to fabricate TiO2nanostructures on To foil. The morphology and structure of the TiO2layer could be controlled conveniently by varying the constituents of the solvent:hydrothermal method produced film with nanofibers, while grass-and honeycomb-like nanostructured films were obtained when ethanol and ethylene glycol were added to the solvent. These films differed widely on their structures and produced different photocurrent responses. The film composed of TiO2nanofibers was varied to have the best photoelectrochemical performance. Finlly, highly ordered TiO2nanotube arrays were prepared through a two-step anodization of Ti foil using the footprints formed in the first anodization as a template. The excellent properties made the TiO2nanotube arrays a highly sensitive photoelectronchemical sensor for organic compounds.Vertically ordered BiOCl nanosheet arrays were fabricated on FTO substrate through a solvothermal method. The temperature and reaction time of the solvothermal process had significant effects on the nucleation and growth of BiOCl. If temperature was lower than100℃, BiOCl nanosheets could not be grown on FTO substrate, but the probability for BiOCl nanosheets to grow on FTO substrate increased when increasing the solvothermal temperature from120℃to180℃. Moreover, the BiOCl nanosheets on FTO substrate became denser and denser as the reaction time extended, and perfect BiOCl nanosheet arrays were formed after8h reaction. The degradation of methyl orange (MO) proved that the photocatalytic activity of the BiOCl nanosheet arrays was as well as P25nanoparticulate film and much better than rutile TiO2nanorod arrays, although the BiOCl layer was much thinner than the other two layers. In reiterative experiments, the BiOCl nanosheet arrays exhibited high photocatalytic stability which was benefited from the strong junction between the nanosheet arrays and the FTO substrate.Because of the selective growth of BiOCl on FTO layer, the FTO substrate was patterned by removing parts of the FTO layer to perform patterned growth of BiOCl nanosheet arrays according to the predesigned path. A microchannel with its inner wall modified by BiOCl nanosheet arrays was constructed based on this feature, and a new photocatalytic microreactor was fabricated. Rapid, effective and continuous-flow photocatalysis could be achieved. The degradation ratio of85%was obtained when residence time for MO in the microchannel was100s. If the complexity or length of the microchannel was increased to prolong the residence time, a higher degradation ratio could be expected.A microfluidic device for determination of chemical oxygen demand (COD) was fabricated based on the photoelectrocatalysis of TiO2nanofiber films. The highly transparent poly (dimethyl siloxane)(PDMS) was employed to fabricate the device by a templateless prototyping using a pulsed CO2laser. Three-electrode system including the TiO2nanofiber film working electrode, Ag/AgCl reference electrode and Pt counter electrode, was intergrated into the microfluidic device. COD was quantified by measuring the charge Qnet in exhaustive degradation of the organic compounds. Qnet was found to be linearly related to the organic concentration, and a linear relationship was also observed between Qntt and the theoretical COD values for the sample with COD range of0-250mg/L. The results demonstrated the practicability of the photoelectrocatalysis for COD determination. For the sample with lower organic concentration, this method also worked well and gave a real detection limit of0.95mg/L which was much lower than that obtained from electrocatalytic and standard method. In analysis of real samples, the COD were measured by both the conventional dichromate method and the microfluidic device, and the result showed that the two methods agreed very well.
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