纳米TiO2光催化剂改性研究进展

综述近年来关于纳米TiO2光催化剂的改性研究进展,详细叙述针对该催化剂的各种改性方法的原理,制备方法及目前的研究进展,展望该领域的研究方向.提出以共掺杂为基础的改性、可重复利用的催化剂以及纳米TiO2薄膜制备和大型反应器的设计是研究的主要课题.     

复合纳米TiO2光催化净化大气环保涂料研究进展

综述复合纳米TiO2光催化净化大气环保涂料研究进展,着重介绍该涂料制备工艺中纳米TiO2改性研究和纳米粉体在涂料中的分散和分散稳定性的研究近况。     

高级氧化技术中分子筛负载纳米TiO2的光催化性能的研究

选择溶胶-凝胶方法制作纳米TiO₂,且将纳米TiO₂负载于分子筛上面。实验结果表明,与非负载光催化剂相比,负载光催化剂具体性能更优。针对目标物实行降解时,最优条件为,pH值是4.7,H₂O₂最初的物质的量浓度是25 mmol/L,甲基橙最初的质量浓度是20 mg/L,增加量是2 g;温度升高有利于降解;随应用频次提升,催化剂具体活性渐渐下降。     

掺Ag复合纳米TiO2光催化性能

通过溶胶-凝胶法和光还原法制备掺Ag复合纳米TiO2.用XRD表征了TiO2的晶体形态.以典型偶氮结构的甲基橙水溶液为模拟对象,研究掺Ag复合纳米TiO2光催化性能.实验结果表明,TiO2悬浮体系中甲基橙的光催化降解符合Langmuir动力学规律.根据动力学计算,掺Ag复合TiO2和单纯TiO2对甲基橙的降解速率常数分别为27.34mg/(L·h)和14.42mg/(L·H),光催化的活性提高了近2倍.因此有望通过这一技术制备出比单纯TiO2更好的光催化剂.     

硅胶负载溴掺杂纳米TiO2的制备与光催化性能研究

利用水热法制备了SiO2负载型溴掺杂纳米TiO2光催化剂(BTS),利用XRD、BET和UV-Vis DRS等测试手段对其进行表征,以苯酚的光催化降解为模型反应,考察了其光催化活性.结果表明:700℃焙烧、钛与硅的摩尔比为3∶1时,BTS具有最佳光催化活性.TiO2以锐钛矿相存在,晶体平均晶粒尺寸为45.5nm,负载后催化剂的比表面积为112.8m2/g,BTS对苯酚的降解率从纯TiO2的27.1％提高到85.6％.     

染料敏化纳米薄膜太阳电池TiO2薄膜的研究进展

主要从染料敏化纳米薄膜太阳电池（以下简介DSCs）的工作原理出发，分别对染料敏化纳米薄膜太阳电池中纳米多孔TiO2薄膜的最新研究和实验进行了讨论，并指出了纳米多孔TiO2薄膜研究中所存在的、影响电池效率的一些主要问题，以及可能的解决方法。     

利用TiO2光催化烟气同时脱硫脱硝的实验研究

制备了固定型TiO2光催化剂,在自行设计的光催化反应器上进行了烟气脱硫脱硝实验研究,考察了氧气浓度、烟气湿度、照射时间,停留时间对脱硫、脱硝效率的影响.实验表明:有氧条件下,反应器预通水蒸汽时间控制在15 min左右,通入烟气后,照射时间100 min,获得脱硫效率为98%,脱硝效率为67%的结果.并对脱硫脱硝反应机理进行了探讨.     

磁控溅射法制备TiO2薄膜的光催化特性

采用中频磁控溅射法与弧抑制技术相结合制备出了廉价、大面积、光催化效果好并且膜与衬底结合牢固的TiO2薄膜。通过改变衬底材料、薄膜厚度、掺杂类型等参数,发现在不锈钢丝网衬底上制备的氮掺杂薄膜在500nm厚时具有最好的光催化效果。用此方法制备TiO2薄膜可以大面积连续生产,具有廉价、催化性能好,与衬底结合牢固、方便应用等优点,因而可以广泛的应用于空气净化器中,从而有利于TiO2光催化薄膜的产业化发展。     

不同光源对TiO2光催化降解染料污染物的影响

考察了在紫外光和可见光作为光源时，TiO2光催化降解偶氮染料酸性橙7(AOT)的差异。实验结果表明，在两种不同的光源下，AO7都能够被有效地降解，而且AO7降解都是以C-N化学键的断裂开始的。以可见光作为光源时，AO7分子结构中的苯环较难开环，AO7的矿化率比较低；而以紫外光作为光源时，AO7能够被彻底矿化。另外，以可见光作为光源时，AO7的降解反应主要发生在催化剂的表面，而以紫外光作为光源时，AO7的降解反应主要发生在溶液中。     

松子壳基活性炭光催化剂的制备及其催化性能研究

为了提高TiO_2光催化剂对水体有机污染物的降解能力,将松子壳基活性炭作为载体负载TiO_2,研究载体比表面积、载体与TiO_2的复合比例以及煅烧温度对复合光催化剂降解水体有机污染物亚甲基蓝的影响。通过BET,XRD,FTIR和SEM分析方法对复合光催化剂的比表面积、晶体结构、有机官能团和表面形貌进行了表征。研究结果表明:适当的增加载体的比表面积,有利于Ti O2的负载和复合光催化剂催化活性的提高;当活化水量为1.5 mL/min时,在充分的水蒸气活化反应下,松子壳炭可制备成比表面积为634.65 m~2/g的活性炭,使其负载TiO_2后具有较好的亚甲基蓝吸附作用和光降解作用;当TiO_2与活性炭的质量比为0.8∶1时,复合光催化剂的催化效果较好;当煅烧温度为450℃时,复合光催化剂具有较优的催化效果,降解率可达77.10%。     

A systematic study of photocatalytic H2 production from propionic acid solution over Pt/TiO2 photocatalyst

The propionic acid (HPr) is one of the main by‐products during fermentative H₂ process. To efficiently convert HPr to H₂ gas, photocatalytic H₂ production from HPr solution with the use of Pt/TiO₂ photocatalyst under ultraviolet light has been studied in this research. The Pt/TiO₂ photocatalyst has been prepared by the sol–gel method and further characterized by X‐ray diffraction, TEM and XPS. Effects of Pt loading amount, HPr concentration, initial pH value on photocatalytic H₂ production have been investigated in detail. From practical point of view, the H₂ evolution from HPr solution under UV irradiation for prolonged time has been studied as well. The Langmuir model can be able to describe the relationship between HPr concentration with the maximum rate of H₂ production. The apparent quantum efficiency and apparent energy conversion efficiency are found to 1.65 and 0.72%, respectively. To better understand the photocatalytic H₂ process over Pt/TiO₂, a possible mechanism for the degradation of HPr has been proposed as well. Based on our results, an efficient route for hydrogen production from renewable biomass can be established by coupling biological H₂ production process with photocatalytic H₂ production process. Copyright © 2010 John Wiley & Sons, Ltd.     

Photocatalytic hydrogen production from glycerol–water mixture over Pt‐N‐TiO2 nanotube photocatalyst

The effects of several modifications on TiO₂ P25 in producing hydrogen from glycerol–water mixture have been investigated. Prior to further modification, TiO₂ underwent hydrothermal treatment at 130°C for several hours to obtain nanotube shape. TiO₂ nanotubes (TiNT) was then doped with platinum (Pt) and nitrogen (N) by employing photo‐deposition and impregnation method, respectively. SEM and XRD results showed that Pt‐N‐TiNT was successfully obtained as pure anatase crystal structure. The effects of glycerol content to photocatalytic activity of hydrogen production have also been studied, result in 50%v of glycerol as the optimum concentration correspond to the stoichiometric volume ratio of glycerol reforming. The results of photo‐production test showed that TiNT (nanotube) could enhance hydrogen generation by two times compared with unmodified P25 (nanoparticle). Meanwhile, simultaneous modification of TiNT by Pt and N dopants (Pt‐N‐TiNT) lead to activity improvement up to 13 times compared with P25. The output of this study may contribute toward finding an alternative pathway to produce H₂ from renewable resources. Copyright © 2012 John Wiley & Sons, Ltd.     

Commercial TiO2 loaded with NiO for improving photocatalytic hydrоgen prоduction in the presence оf simulated solar radiation

Five NiO/TiO₂ materials with a different mass ratiо оf NiO tо TiO₂ (3.3, 6.7, 16.3, 23.7, and 36.8%) were synthesized by wet impregnation process and characterized by DR UV-vis, scanning electrоn micrоscоpe, transmissiоn electrоn micrоscоpy, X-ray diffractiоn methоd, N₂ physisorption, and temperature-programmed reduction. The characterizatiоn confirmed the existence of nano-sized cubic NiO on the commercial TiО₂. The оbserved interactiоn between TiO₂ and NiО phases confirmed that the оbtained material dоes nоt constitute a physical mixture оf twо species. The photocatalytic hydrоgen generatiоn efficiency [mоnitored by gas chromatography–thermal conductivity detector (GC-TCD)] of these materials from methanol-water mixtures under simulated solar radiation and artificial UV radiation was investigated. For some synthesized NiO/TiO₂ materials, higher photocatalytic efficiency was found compared with the commercial TiO₂ Degussa P25 catalyst. Also, the obtained results showed that 0.125 g L⁻¹ of 6.7%NiO/TiO₂ and 5% (v/v) of methanol were the optimal operating parameters. Furthermоre, fоr the mоst efficient phоtоcatalytic system under the influence оf simulated solar radiation, a 1.8 times higher hydrоgen prоduction rate was achieved cоmpared tо that under the influence оf artificial UV radiatiоn.     

Enhanced TiO2 photocatalysis by Cu in hydrogen production from aqueous methanol solution

Cu particles have been deposited on TiO₂ by incipient-wetness impregnation followed by low-temperature (400°C) calcination/reduction, and the metallization process leads to significant enhancement in photocatalytic activity of TiO₂ for H₂ production from aqueous methanol solution. The activity exhibits up to 10-fold enhancement at the optimum loading of 1.2 wt% Cu. Spectroscopic studies indicated that the Cu particles were oxidized during reaction to have a valence lower those of thermally oxidized particles, which showed inferior activities. Dissolution of Cu ion in TiO₂ lattice, in contrast, resulted in reduction in photocatalytic activity.     

Interfacial charge transfer and photocatalytic activity in a reverse designed Bi2O3/TiO2 core-shell

In this study, the electronic and photocatalytic properties of core-shell heterojunctions photocatalysts with reversible configuration of TiO₂ and Bi₂O₃ layers were studied. The core-shell nanostructure, obtained by efficient control of the sol-gel polymerization and impregnation method of variable precursors of semiconductors, makes it possible to study selectively the role of the interfacial charge transfer in each configuration. The morphological, optical, and chemical composition of the core-shell nanostructures were characterized by high-resolution transmission electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The results show the formation of homogenous TiO₂ anatase and Bi₂O₃ layers with a thickness of around 10 and 8 nm, respectively. The interfacial charge carrier dynamic was tracked using time resolved microwave conductivity and transition photocurrent density. The charge transfer, their density, and lifetime were found to rely on the layout layers in the core-shell nanostructure. In optimal core-shell design, Bi₂O₃ collects holes from TiO₂, leaving electrons free to react and increase by 5 times the photocatalytic efficiency toward H₂ generation. This study provides new insight into the importance of the design and elaboration of optimal heterojunction based on the photocatalyst system to improve the photocatalytic activity.     

Recent progress in metal-doped TiO2, non-metal doped/codoped TiO2 and TiO2 nanostructured hybrids for enhanced photocatalysis

Titanium dioxide remains a benchmark photocatalyst with high stability, low cost, and less toxicity, but it is active only under UV light; thus, in practical applications using visible light, its catalytic reactions are stalled. To enhance its catalytic activity under visible light, non-metal/codoped TiO₂ structures are being studied. These structures improve the photocatalytic activity of TiO₂ in visible light by reducing its energy bandgap. This might be useful in wastewater treatment for the photocatalytic degradation of organic contaminants under visible and UV light irradiation. In this intensive review, we describe recent developments in TiO₂ nanostructured materials for visible-light driven photocatalysis, such as (i) mechanistic studies on photo-induced charge separation to understand the photocatalytic activity and (ii) synthesis of non-metal doped/codoped TiO₂ and TiO₂ nanostructured hybrid photocatalysts. Furthermore, the effects of various parameters on their photocatalytic efficiency, photodegradation of various organic contaminants present in wastewater, and photocatalytic disinfection are delineated.     

Two‐step hydrothermal fabrication of Na0.23TiO2 nanofibers and enhanced photocatalysis after loaded with gold or silver determined by surface potentials

Pure Na_0.23TiO₂ nanofibers were fabricated by a two‐step hydrothermal method after a series of experiments. Na_0.23TiO₂ is a direct bandgap semiconductor and exhibits a strong photodegradative ability for RhB, which is difficult to be degraded. The photodegradative activity is much enhanced after loaded noble metal Au or Ag nanoparticles on Na_0.23TiO₂ nanofibers by a chemical bath deposition method. Hot electrons are generated in metal nanoparticles through a localized surface plasmon (LSP) process under light illumination and then diffuse to a semiconductor and reduce the surface potential, which is detected directly by a scanning Kelvin probe microscopy (SKPM). The high electromagnetic field induced by the LSP resonance and strong coupling between noble metal and Na_0.23TiO₂ are beneficial for the utilization of visible light, electron produce, charge transportation, and separation, as a result, promoting the activity of semiconductor‐based photocatalysts. This work supplies an effective method to directly probe the surface plasmon and highlights the application of Na_0.23TiO₂ in photocatalysis.     

Ce掺杂TiO2光催化剂的制备及降解偶氮废水的研究

采用溶胶—凝胶法制备Ce掺杂TiO2光催化剂,借助XRD、HRTEM对其进行表征,分析了Ce含量、煅烧温度等因素对光催化降解偶氮废水活性的影响。结果表明,铈掺杂在提高了TiO2光催化剂催化活性的同时也抑制了相转变。当Ce的掺杂量为3%时,对偶氮废水的处理率可高达92.3%。     

Waste water recycling supplied by renewable energies - basic conditions and possible treatment technologies

The providing of pure water for human needs and irrigation is one of the most important problems of many countries in hot climate. Moreover waste water is not purified at all or insufficiently. Purified waste water could be used by mankind e.g. for irrigation in order to establish a closed water circulation. Excellent solar- and wind conditions in the regions with hot climate suggest an energy supply with renewable energies for many applications. The feasibility of the combination of purification plants with a renewable energy supply is investigated. The investigations are carried out as follows: first of all the problematic of water and energy supply in developing countries is described. Then a general analysis of the system structure in view of the energy supply is made. A waste water treatment plant (WWTP) with a low energy demand which is adapted to a renewable power supply is designed. To present the investigations more clearly they refer to data representative for Jordan.