低含量Ni掺杂TiO2光催化剂及其在水溶液体系中的重复使用性能

利用溶胶-凝胶法制备了低含量Ni掺杂的TiO₂光催化剂粉体,考察了催化剂在甲基橙水溶液中的重复使用性能,并用XRD、XPS和N₂吸附-脱附等手段对催化剂进行了表征分析。结果表明,当掺杂Ni物质的量分数为0.3%和焙烧温度400 ℃时,制备的Ni/TiO₂的光催化降解甲基橙水溶液的活性高于纯TiO₂的光催化降解活性。Ni/TiO₂光催化剂在水溶液体系重复使用过程中,催化活性急剧下降,重复使用性能较差。Ni掺杂使TiO₂上产生具有较低结合能的低价钛离子如Ti^3＋,使表面缺陷（或氧空位）增加。比表面积和氧空位增加可能是Ni掺杂提高TiO₂光催化活性的主要原因。Ni流失可能是Ni/TiO₂在水溶液体系中重复使用性能较差的原因。     

Fe3+和Ce3+掺杂对TiO2光催化剂性能的影响

采用溶胶-凝胶法在玻璃纤维上涂层TiO₂光催化剂,并掺杂Fe³⁺和Ce³⁺修饰TiO₂光催化剂,进行了间歇式光催化降解气相苯实验,结果表明掺杂Fe³⁺和Ce³⁺均可以提高TiO₂光催化剂的活性,其中0.2% Fe³⁺/TiO₂光催化剂活性最好.借助XRD、SEM和XPS等表征手段来分析修饰前后的催化剂表面的物理化学性质变化,研究表面性质的变化对于光催化性能的影响.表征结果显示载体玻璃纤维表面均匀分布了粒径为40～60 nm的锐钛型TiO₂微粒,0.2%Fe³⁺和Ce³⁺掺杂后催化剂表面Ti³⁺浓度增大,表面羟基浓度减小.催化剂表面的Ti³⁺会与被吸附氧气反应形成Ti⁴⁺并同时产生活性组分O^-₂,氧化剂O^-₂在光催化降解苯反应过程中起着重要作用.     

掺杂铁纳米TiO2的制备及其光催化性能研究

分别采用水热法和溶胶-凝胶法制备了纳米级TiO₂和不同掺铁量的TiO₂纳米粒子。通过纯TiO₂和掺铁TiO₂分别作光催化剂时甲基橙溶液在紫外光下的光催化降解试验发现，溶胶-凝胶法掺杂铁离子可以有效地提高TiO₂光催化活性，而水热法掺杂铁使TiO₂的光催化活性明显降低。Fe/TiO₂摩尔比为0.01％～0.1％，随掺杂量的增大,TiO₂光催化活性逐渐降低。     

水处理光催化剂TiO2掺杂改性研究进展

TiO₂ 光催化是一种可以利用太阳光的高级氧化技术,在水处理方面具有广阔的应用前景,但该技术目前大都吸收紫外光,对可见光利用效率很低,急需研究可提高TiO₂ 光催化性能的改性方案。本文综述了近年来 TiO₂ 金属掺杂、非金属掺杂以及共掺杂改性的理论与技术研究进展,对各种改性后的TiO₂ 光催化效率及其对可见光的响应进行了综合分析与比较,并提出了展望。     

TiO2光催化剂掺杂改性的研究进展

TiO₂在利用光能和环保等领域具有重要应用前景。由于TiO₂具有较大禁带宽度，限制其对太阳光等可见光能的利用。通过对TiO₂掺杂改性，合成出具有较窄禁带宽度和稳定性好的光催化剂，促进光催化剂的实际应用。介绍了TiO₂光催化作用机理，从金属掺杂、非金属掺杂和共掺杂等方面总结TiO₂催化剂掺杂改性的研究现状。     

沸石负载TiO2的光催化性能

以钛酸正丁酯和沸石为主要原料，采用溶胶-浸渍法制备出负载型纳米TiO₂/沸石催化剂。对亚甲基蓝模拟废水进行了光催化降解研究。分析比较了负载与非负载TiO₂降解效果的差异。探讨了pH对光催化降解率的影响。用FT-IR进行了结构表征。对催化剂进行了回收再生试验。结果表明，沸石负载的TiO₂光催化剂具有良好的光催化活性、不易失活及可再生性，TiO₂最佳负载量为2.98%。     

掺镧纳米TiO2的光催化性能研究

研究了掺镧纳米TiO₂的物理特性及光催化活性，探讨了它们之间的关系，通过对甲基橙和罗丹明两种不同结构物质的降解实验，发现掺镧纳米TiO₂光催化性能具有广泛性。用于实际印染废水处理，再次验证掺镧能提高TiO₂的光催化效能，掺镧摩尔分数为0.02%时光催化效果最好。     

Ag/TiO2光催化降解茜素红

以钛酸四丁酯为前驱体,冰醋酸为水解抑制剂,用溶胶-凝胶法制备了纳米Ag/TiO₂复合催化剂,测定了催化剂对茜素红溶液的光降解活性。结果表明,Ag/TiO₂催化剂具有较高的光催化活性。     

离子液体中微波辅助制备硫掺杂纳米TiO2光催化剂

以钛酸丁酯为前驱物,在离子液体（1-丁基-3-甲基咪唑六氟磷酸盐）、水和无水乙醇所组成的混合溶剂中采用溶胶-凝胶法及微波干燥,制备了硫掺杂纳米TiO₂光催化剂。采用XRD对催化剂的结构进行了表征,以甲基橙为模拟污染物,高压汞灯和卤钨灯为光源,考察了掺杂量、微波干燥等因素对硫掺杂TiO₂光催化剂活性的影响。结果表明,硫掺杂TiO2催化剂活性高于未掺杂TiO₂催化剂;且当硫脲与钛酸丁酯物质的量比为5.0,在家用微波炉于功率210 W干燥25 min,再在马弗炉600 ℃焙烧处理2 h制备的催化剂,具有最佳的光催化降解效果。     

过渡金属离子掺杂纳米TiO2的相变与光催化活性

采用溶胶-凝胶法制备了掺杂Mo⁶⁺、Cr³⁺、Fe³⁺的改性纳米TiO₂光催化剂，并分别在550℃和580℃下对其进行了热处理，考察了热处理温度对掺杂纳米TiO₂相变和光催化活性的影响.通过光催化降解染料罗丹明B实验，对在不同热处理温度下Mo⁶⁺、Cr³⁺、Fe³⁺改性以及不同Mo⁶⁺掺杂量的TiO₂光催化活性进行了评价，发现掺杂离子对TiO₂光催化活性的影响与其对TiO₂相转变的作用是一致的，即抑制相转变的同时也提高了光催化活性.实验结果也进一步表明，Mo⁶⁺掺杂量为0.05％（摩尔分数）时的TiO₂具有最佳光催化活性.     

Synthesis and visible‐light‐derived photocatalysis of titania nanosphere stacking layers prepared by chemical vapor deposition

BACKGROUND: In this study, visible‐light‐derived photocatalytic activity of metal‐doped titanium dioxide nanosphere (TS) stacking layers, prepared by chemical vapor deposition (CVD), was investigated. The as‐grown TS spheres, having an average diameter of 100–300 nm, formed a layer‐by‐layer stacking layer on a glass substrate. The crystalline structures of the TS samples were of anatase‐type. RESULTS: Ultraviolet (UV) absorption confirmed that metallic doping (i.e. Co and Ni) shifted the light absorption of the spheres to the visible‐light region. With increasing dopant density, the optical band gap of the nanospheres became narrower, e.g. the smallest band gap of Co‐doped TS was 2.61 eV. Both Ni‐ and Co‐doped TS catalysts showed a photocatalytic capability in decomposing organic dyes under visible irradiation. In comparison, Co‐doped TiO₂ catalyst not only displays the adsorption capacity, but also the photocatalytic activity higher than the N‐doped TiO₂ catalyst. CONCLUSION: This result can be attributed to the fact that the narrower band gap easily generates electron–hole pairs over the TS catalysts under visible irradiation, thus, leading to the higher photocatalytic activity. Accordingly, this study shed some light on the one‐step efficient CVD approach to synthesize metal‐doped TS catalysts for decomposing dye compounds in aqueous solution. Copyright © 2010 Society of Chemical Industry     

A Visible Light Photocatalyst of Carbonate‐Like Species Doped TiO2

Carbon‐doped TiO₂ nanomaterials have been successfully synthesized via an effective two‐step procedure involving hydrothermal method and followed by a low‐temperature calcination treatment process, through which a controllable amount of carbonate‐like species could be incorporated into TiO₂. First‐principles calculations suggest the TiO₂ doped with carbon in form of carbonate‐like species can effectively extend the adsorption of the material from ultraviolet region to visible light. And it is experimentally found that carbon‐doped TiO₂ nanomaterials exhibit much higher photocatalytic activity than reference P25 and TiO_2?xN_x catalysts toward the liquid‐phase degradation of organic pollutants under visible light (420 nm < λ < 800 nm) irradiation. The presence of synergic effect between carbonate‐like doping and anatase TiO₂ is believed to play an essential role in affecting the photocatalytic reactivity, and the response to the visible light is ascribed to the narrowed band gap energy controlled by carbon doping. Moreover, the roles of active species in the photocatalytic process are compared using different types of active species scavengers. Meanwhile, the degradation mechanism of the photocatalysis is proposed. It is hoped that our work could provide valuable information on the design of carbonate‐like doped semiconductor with more excellent properties and set the foundation for the further industrial application.     

Highly visible-light active C- and V-doped TiO2 for degradation of acetaldehyde

C-doped and C- and V-doped TiO₂ photocatalysts were prepared by a sol–gel process. Both catalysts showed high activity for the degradation of acetaldehyde under visible irradiation (>420 nm). The co-doped TiO₂ catalysts also were highly active in the dark; 2.0% V-containing co-doped TiO₂ had the highest activity, comparable with the activity under visible light irradiation. The catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), and N₂ adsorption–desorption. The results suggest that vanadium ions were introduced both on the surface and into the bulk of TiO₂. A free electron, induced by the formation of V⁵⁺ in the sublayers of TiO₂ during calcination at 500 °C in air, was delocalized and promoted into the conduction band by thermal energy and further transferred to O₂, generating a superoxide radical anion (O⁻₂) that is responsible for degradation of acetaldehyde in the dark. In addition to functioning as a photosensitizer that shifts the optical response of TiO₂ from the ultraviolet (UV) to the visible light region, the doped elemental carbon increased the surface area and improved the dispersion of vanadium.     

Photocatalytic activity of undoped and sulfur-doped TiO2 films grown by MOCVD for water treatment under visible light

Titanium dioxide ceramic coatings have been used as catalysts in green technologies for water treatment. However, without the presence of a dopant, its photocatalytic activity is limited to the ultraviolet radiation region. The photocatalytic activity and the structural characteristics of undoped and sulfur-doped TiO₂ films grown at 400 °C by metallorganic chemical vapor deposition (MOCVD) were studied. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under visible light. The results suggested the substitution of Ti⁴⁺ cations by S⁶⁺ ions into TiO₂ structure of the doped samples. SO₄^2? groups were observed on the surface. S-TiO₂ film exhibited good photocatalytic activity under visible light irradiation, and the luminous intensity strongly influences the photocatalytic behavior of the S-TiO₂ films. The results supported the idea that the sulfur-doped TiO₂ films grown by MOCVD may be promising catalysts for water treatment under sunlight or visible light bulbs.     

Effects of V and Zn codoping on the microstructures and photocatalytic activities of nanocrystalline TiO2 films

To enhance the photocatalytic activity of TiO₂, V and Zn co-doped TiO₂ films were synthesized by the sol–gel method. The experimental results indicated that the films were composed of round-like nano-particles or aggregates. V and Zn codoping could not only obviously increase the specific surface area of TiO₂ but also result in the narrowed band gap of TiO₂ sample. The photocatalytic activities of the TiO₂ films were evaluated by the photocatalytic decomposition of organic dyes in aqueous solution. Compared with un-doped TiO₂ film or single doped TiO₂ film, V and Zn co-doped TiO₂ film exhibited excellent photocatalytic activities under both UV light and visible light. The improvement mechanism by V and Zn codoping was also discussed.     

超声波及压力处理的TiO2柱撑蒙脱土的制备与光催化性能

引言 近十多年来,随着环境污染日益严重,利用半导体粉末作为光催化剂催化氧化降解有机物的研究已成为热点[1].TiO2作为典型N型半导体光催化剂,由于活性高、化学稳定性好以及对人体无害等特点,成为理想的环保型光催化剂[2].     

Titania and Noble Metals Deposited Titania Catalysts in the Photodegradation of Tartazine

Nanoparticles of TiO₂ were synthesised by sol–gel technique and photo deposition of about 1% noble metal (M/TiO₂, M = Ag, Au, and Pt) on TiO₂ was carried out. The catalysts were characterised by XRD, TEM, BET, FT-IR, and UV–Visible spectroscopy. Using commercial TiO₂ (P-25 Degussa), the conditions such as dye concentration, catalyst weight and pH were optimized for complete decolourisation of textile dye tartazine (TAZ) under UV and visible irradiations. Among the catalysts tested, the synthesised TiO₂ showed better photocatalytic activity than TiO₂ (P-25 Degussa). Whereas, M/TiO₂ catalysts showed remarkable photocatalytic activity towards the decolourisation of TAZ even under visible irradiation. This enhanced activity of M/TiO₂ catalyst may be attributed to the trapping of conduction band electrons by noble metals.     

S–N Co-Doped TiO2 Photocatalysts with Visible-Light Activity Prepared by Sol–Gel Method

S–N co-doped anatase nanosized TiO₂ photocatalyst was successfully prepared by simple sol–gel method. The samples were characterized by XRD, XPS, UV–Vis. From the results of UV–Vis, a red shift of the absorption edge was brought out owing to the S and N codoping. XPS and UV–Vis studies revealed that N and S were in situ codoped in the lattice of TiO₂ and the absorbance in visible light region decreased with the calcination temperature increased. The photocatalytic activity was evaluated by the photocatalytic oxidation of penicillin solution under visible light irradiation. The results show that visible-light induced photocatalytic activities of the as-prepared TiO₂ powders were improved by S–N copoing. The high activity of S–N co-doped TiO₂ can be related to the results of the synergetic effects of strong absorption in the UV–Vis region, red shift in adsorption edge.     

Li–Y doped and codoped TiO2 thin films: Enhancement of photocatalytic activity under visible light irradiation

Sol−gel synthesis based on the self-assembling template method has been applied to synthesize Li–Y doped and co-doped TiO₂ not only to improve simultaneously the structural and electronic properties of TiO₂ nanomaterials but also to achieve Li–Y doping of titania with high photocatalytic reactivity. The characterization of the samples was performed by GXRD, GSDR, FT-IR, and Raman spectroscopy. According to the GXRD patterns, all the observed reflections can be indexed using the anatase form of TiO₂, Which is confirmed by ground state diffuse reflectance and micro-Raman spectra. The Li–Y doped titania materials immobilized as nanostructured thin films on glass substrates exhibit high photocatalytic efficiency for the degradation of toluidine and benzoic acid under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.     

钨、氮共掺杂TiO2的制备及其光催化性能研究

为了更好的利用太阳能,以钛酸正丁酯为前驱体,硝酸铵和钨酸铵为掺杂离子给体,通过溶胶-凝胶法,室温下成功制备了纯TiO2和钨、氮掺杂和共掺杂的TiO2光催化剂.表征结果显示,共掺杂催化剂为锐钛矿型,外观呈球形,感光范围拓展到可见光区域.以甲基橙为降解物,氙灯为模拟太阳光光源,进行光催化降解实验,钨、氮共掺杂TiO2在光照...