TiO_2光催化净化室内低浓度氮氧化物

氮氧化物是室内环境中危害人体健康的重要污染物之一,主要介绍TiO2光催化氧化法去除氮氧化物的机理,影响氮氧化物光催化转化的因素,如初始浓度、温湿度、停留时间和光强等;目前常见的提高氮氧化物光催化转化的方法,如Fe3+离子掺杂和TiO2与活性炭纤维ACF复合等;以及TiO2催化剂失活再生问题。

Degradation of Antibiotics in Aqueous Solution by Photocatalytic Process： Comparing the Efficiency in the Use of ZnO or TiO2

The study examined the photodegradative efficiency of ZnO and TiO2 in degradation of antibiotics in aqueous matrices. Among several types of antibiotics, four antibiotics were chosen to feature the major classes of these compounds： amoxicillin, erythromycin, streptomycin and ciprofloxacin. Degradation of antibiotic solutions was carried out mainly under UV-light irradiation in a set time with the presence of small quantity of zinc oxide or titanium dioxide. Solutions were analyzed with HPLC chromatography and degradation percentages were calculated from ratio between pick area associated to no degraded drug solution and degraded drug solution＇s pick area. Meanwhile, toxicity of antibiotics and degrading compounds were investigated using a biosensor system, consisting of Clark＇s electrode associated with a portion of agar medium culture containing Saccharomyces Cerevisiae yeast cells. This way, it was possible to define the oxygen that was consumed by yeast cells. Toxicity associated to antibiotics and degrading products are related to decrease of oxygen concentration in solution. It is clear that zinc oxide is slower than titanium dioxide to degrade antibiotics, but zinc oxide shows better photodegradation efficiency than titanium dioxide in spite of its small specific superficial area.

Photocatalytic Degradation of Methylene Blue with Side-glowing Optical Fiber Deliverying Visible Light

The side-glowing optical fibers (SOFs) were chosen as the conducting medium of endogenous light; and 20 mg·L-1 methylene blue was chosen as the target to be degraded. The SOF is made up of quartz core with a silicon cladding, which can emit light through side surface more uniformly and transmit light for longer distance to avoid attenuation of light by liquid medium. The filament lamp was chosen as visible light source. Different reaction conditions, such as the presence of optical fiber or not, the quantity of SOF, light irradiation intensity were tested by measuring the methylene blue degradation of methylene blue. The results show that suitable reaction conditions were 1.167 g·L-1 Ag + /TiO 2 with 7% (by mass) of Ag + doped in TiO 2 , and 500 roots of SOF (30 cm length in solution). The photocatalytic degradation efficiency under 300W lamp irradiation for 8h was about 97%. And the photocatalytic degradation efficiency of methylene blue degradation was proportional to SOF quantity, light irradiation intensity and catalytic dosage within a certain range. Compared with general UV and visible light SOFs could save a huge amount of energy and cost, in the potential applications in dealing with organic pollutants on a large scale.

In situ synthesis of graphitic-C3N4 nanosheet hybridized N-doped TiO2 nanofibers for efficient photocatalytic H2 production and degradation

Graphitic carbon nitride nanosheets （g-C3N4 NSs） hybridized nitrogen doped titanium dioxide （N-TiO2） nanofibers （GCN/NT NFs） have been synthesized in situ via a simple electrospinning process combined with a modified heat-etching method. The prepared GCN/NT NFs were characterized by a variety of methods and their photocatalytic activities were evaluated by hydrogen （H2） production from water splitting and degradation of rhodamine B in aqueous solution. It was found that the GCN/NT NFs have a mesoporous structure, composed of g-C3N4 NSs and N-doped TiO2 crystallites. The g-C3N4 NSs synthesized after heat-etching were found to be embedded in, and covered, the hybrid NFs to form stable interfaces. The partial decomposition of g-C3N4 releases its nitrogen content which eventually gets doped into the nearby TiO2 skeleton. The GCN/NT NFs give a high photocatalytic H2 production rate of 8,931.3 μmol·h^-1·g^-1 in aqueous methanol solution under simulated solar light. Such a highly efficient photocatalytic perfor- mance can be ascribed to the combined effects of g-C3N4 NSs and N-doped TiO2 with enhanced light absorption intensity and improved electron transport ability. Also, the large surface area of the mesoporous NFs minimizes light reflection on the surface and provides more surface-active sites. This work highlights the potential of quasi-one dimensional hybrid materials in the field of solar energy conversion.

Improved conversion efficiency of dye-sensitized solar cells by using novel complex nanostructured TiO_2 electrodes

A novel complex nanostructured TiO2 electrode and fabrication process were proposed and demonstrated to improve the performance of dye-sensitized solar cells(DSSCs).In the proposed process,a nanoporous TiO2 layer was firstly fabricated on the FTO(fluorine-doped tin oxide) conducting substrate by an anodization process,then a nanoparticulate TiO2 film was deposited on the nanoporous TiO2 layer by the screen printed method to form the complex nanostructured TiO2 electrode.The experiments demonstrated that the nanoporous TiO layer can enhance the light scattering,decrease the contact resistance between TiO2 electrode and FTO,and suppress the recombination of I3-ion with the injected electrons of FTO.The process variables are crucial to obtain the optimized performance of DSSCs.By adopting the optimized process,improved conversion efficiency of DSSCs was achieved at AM 1.5 sunlight.

TiCl_4 assisted formation of nano-TiO_2 secondary structure in photoactive electrodes for high efficiency dye-sensitized solar cells

A new kind of photoactive electrodes with nanocrystalline TiO2(nano-TiO2)secondary structure is successfully prepared via a simple method of adding a small amount of TiCl4 2-propanol solution in conventional nano-TiO2 paste to form micro-sized nano-TiO2 aggregates.The benefits of this special structure include improved optical absorption,increased light scattering ability,and enhanced electron transport and collection efficiency.Dye-sensitized solar cells(DSCs)based on these photoactive electrodes show improved performance.The power conversion efficiency of the cells can be increased from 5.03%to 7.30%by substituting 6μm conventional nano-TiO2 thin film with the same thickness of as-prepared nano-TiO2 aggregates film in the photoactive electrodes.A higher power conversion efficiency of the cells can be obtained by further increasing the thickness of the nano-TiO2 aggregates film.