Cobalt Ion-Doped TiO(2) Photocatalyst Response to Visible Light

Photocatalytic activity under visible light irradiation was generated by doping a small amount of Co(2+) ions into TiO(2) particles. Nanometer-sized particles with the composition xCoO-(100-x) TiO(2) (xCo/TiO(2); 0300 nm) light irradiation but also induced the visible light (lambda>400 nm) response. The highest photocatalytic activities were obtained at x=0.03 for both irradiations. Copyright 2000 Academic Press.     

Ag@AgCl修饰TiO2-xCx光催化剂的制备及其可见光降解污染物性能

以钛酸丁酯和葡萄糖为原料用水热法制备了碳掺杂二氧化钛,再进一步对其进行Ag@AgCl表面修饰.用X射线衍射(XRD),X射线光电子能谱(XPS),透射电镜(TEM),BET比表面仪和紫外-可见(UV-Vis)漫反射光谱等手段对样品进行测试表征;在可见光辐射下(λ＞420 nm),以甲基橙和苯酚溶液的光催化降解实验来评价样品的活性.结果表明:经Ag@AgCl修饰后,样品的粒径增大,比表面积减小,对可见光的响应增强;可见光光催化效率有大幅度提高,对甲基橙和苯酚的降解效率分别是修饰前的5.5和3.4倍,且光催化剂经三次循环使用后活性基本保持不变.     

Surfaced-modified TiO2 Nanofibers with Enhanced Photodegradation Under Visible Light

Asynchronized surface modification method based on coaxial electrospinning was developed to fabricate high-efficiency photodegradative nanofiber for water purification. TiO₂ nanoparticles assembled uniformly on the surface of polycaprolactone(PCL) nanofibers to form composite nanofibers through one step process. The maximal content of Ti element was 25.6%(mass fraction) in the PCL/TiO₂ composite nanofibrous membrane, which exhibited hydrophilicity and excellent photodegradation under visible light in water. The Rhodamine B dye degraded 96.17% in 120 min under visible light by the PCL/TiO₂ composite membrane. The adsorption behavior fitted Langmuir model well and indicated chemical related adsorption. This PCL/TiO₂ composite nanofibrous membrane has super degradation properties and displays great application potential to environmental protection.     

SiO2负载的TiO2光催化剂可见光催化降解染料污染物

 采用酸催化溶胶-凝胶法制备了SiO2负载的TiO2光催化剂,考察了制备条件对负载型TiO2光催化剂的晶相、结构、比表面积和可见光催化活性的影响. 结果表明,采用SiO2为载体时,TiO2以纳米颗粒的形态分散在载体表面,负载型TiO2/SiO2催化剂的比表面积大、等电点低而且热稳定性能良好. 偶氮染料酸性橙7的可见光催化降解实验结果表明,染料污染物在催化剂表面的吸附是影响催化剂可见光催化活性的重要因素. 与试剂TiO2样品相比,负载型TiO2/SiO2光催化剂具有更好的光催化活性和沉降性能.     

SiO2/TiO2 Hollow Nanoparticles Decorated with Ag Nanoparticles: Enhanced Visible Light Absorption and Improved Light Scattering in Dye‐Sensitized Solar Cells

Hollow SiO₂/TiO₂ nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible‐light absorption and improve light scattering in dye‐sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO₂/TiO₂ HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO₂ layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO₂‐based DSSCs to 8.1 % with HNP‐based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP‐based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare‐HNP‐based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP‐based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar‐cell performance.     

N、F共掺杂TiO2可见光响应光催化剂的酸催化水解法制备及表征

采用酸催化水解法由TiCl4、NH4F混合液合成N、F共掺杂可见光响应TiO2光催化剂(TONF).以苯酚为模型物,考察了催化剂在可见光区、紫外光区的催化活性.采用X射线光电子能谱(XPS)、紫外.可见漫反射光谱(DRS)、X射线衍射(XRD)、打描电子显微镜(SEM)及低温氮物理吸附对光催化剂的晶相结构、光谱特征和表面结构等进行表征.结果表明,适量的N、F共掺杂TONF催化剂表现出较高的可见光催化活性.N、F共掺杂可显著提高TiO2分散性能,促进锐钛矿相的形成,抑制其向金红石相转变,提高相转变温度.N掺杂可提高TiO2在可见光区的吸收;F掺杂可使TiO2能隙变窄.     

Broadband and Highly Directional Visible Light Scattering by Laser-Splashed Lossless TiO2 Nanoparticles

All-dielectric nanoparticles, as the counterpart of metallic nanostructures have recently attracted significant interest in manipulating light-matter interaction at a nanoscale. Directional scattering, as an important property of nanoparticles, has been investigated in traditional high refractive index materials, such as silicon, germanium and gallium arsenide in a narrow band range. Here in this paper, we demonstrate that a broadband forward scattering across the entire visible range can be achieved by the low loss TiO₂ nanoparticles with moderate refractive index. This mainly stems from the optical interferences between the broadband electric dipole and the magnetic dipole modes. The forward/backward scattering ratio reaches maximum value at the wavelengths satisfying the first Kerker’s condition. Experimentally, the femtosecond pulsed laser was employed to splash different-sized nanoparticles from a thin TiO₂ film deposited on the glass substrate. Single particle scattering measurement in both the forward and backward direction was performed by a homemade confocal microscopic system, demonstrating the broadband forward scattering feature. Our research holds great promise for many applications such as light harvesting, photodetection and on-chip photonic devices and so on.     

Enhanced Visible Light Irradiation Photocatalytic Performance of MgFe2O4 After Growing with ZnO Nanoshell and Silver Nanoparticles

MgFe₂O₄ implanted with ZnO and silver nanoparticles has been successfully synthesized. The formation mechanism of the core~shell structured Ag/ZnO /MgFe₂O₄ nanoparticles was investigated. The efficacy of degradation of an organic dye was compared under the visible light irradiation with the individual components (MgFe₂O₄ , ZnO , and Ag). The structure of Ag/ZnO /MgFe₂O₄ nanoparticles was established from detailed structural analyses using a vibrating‐sample magnetometer (VSM), X‐ray diffraction (XRD ), selected area electron diffraction (SAED ), scanning electron microscopy (SEM ), energy‐dispersive X‐ray spectroscopy (EDS ), and transmission electron microscopy (TEM ). Ag/ZnO /MgFe₂O₄ nanoparticles showed a saturation magnetization (M _s) of 44 emu/g. It is seen from the results that ZnO is coated on the surface of MgFe₂O₄ nanoparticles, and Ag nanoparticles are attached to the edge of the ZnO /MgFe₂O₄ nanoparticles. In addition, the nanoparticles were found to be spherical with appropriate structures. The electron transfer mechanism greatly enhances the rhodamine B (RhB ) degradation rate, which is illustrated and discussed in detail. The obtained Ag/ZnO /MgFe₂O₄ nanoparticles were photostable and magnetically recyclable with potential application in the degradation of organic pollutants.     

Copper Nanoparticles on Graphene Support: An Efficient Photocatalyst for Coupling of Nitroaromatics in Visible Light

Copper is a low‐cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible‐light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm⁻²) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the N O bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.     

Efficient Decomposition of Organic Pollutants Over In2O3/TiO2 Nanocomposite Photocatalyst Under Visible Light Irradiation

The heterojunction structures of In₂O₃/TiO₂, exhibiting visible light photocatalytic efficiency, has been synthesized by utilizing maleic acid as an organic linker to combine In₂O₃ and Degussa P25 (TiO₂) nanoparticles. The prepared nanocomposite has been characterized by FESEM, TEM, XRD and UV?CVisible reflectance spectra. The photocatalytic efficiency of the composite photocatalyst has been investigated based on the decomposition of 2-propanol (IP) in gas phase and 1,4-dichlorobenzene (DCB) in aqueous phase under visible light (??????420?nm) irradiation. The results reveal that the In₂O₃/TiO₂ composite photocatalyst with 7?wt% In₂O₃ demonstrated 6.3 times of efficiency in evolving CO₂ from gaseous IP and 8.7 times of efficiency in removing aqueous DCB in compare with Degussa P25. In this In₂O₃/TiO₂ composite system, TiO₂ seems to be the principal photocatalyst whereas the function of In₂O₃ is to sensitize TiO₂ by absorbing visible light (??????420?nm). The extraordinary high photocatalytic efficiency of this composite In₂O₃/TiO₂ under visible light has been explained on the basis of relative energy band positions of the component semiconductors.     

新型纳米光催化剂La3+/S/TiO2的制备及其可见光活性研究

采用沉淀-浸渍法合成了一种新型La^3＋和S共掺杂TiO2纳米复合光催化剂。通过紫外．可见（UV-Vis）漫反射、X射线衍射（XRD）和透射电子显微镜（TEM）等手段对其物相组成、晶粒尺寸、结晶形态和吸光性能进行了表征。以活性艳蓝198染料溶液为模拟废水，对La^3＋／S/TiO纳米复合光催化剂的活性进行了评价。相对于单一的TiO2，S掺杂的TiO2和La^3＋掺杂的TiO2光催化剂，La^3＋／S/TiO2纳米复合光催化荆颗粒的粒径更小，光的吸收边发生了更大程度的红移。在波长λ〉400nm的可见光光照下，具有最高的光催化活性。     

石墨烯-二氧化钛复合催化剂对光催化性能的提高(英文)

以石墨烯氧化物和钛酸四丁酯为原料,通过水热法、无氧煅烧转晶合成了graphene-TiO2复合催化剂,并采用透射电镜、X射线衍射、拉曼光谱和X射线光电子能谱等手段对其进行了表征.结果表明,TiO2全部为锐钛矿晶型,呈纳米颗粒状附着在薄膜状的graphene表面.以亚甲基蓝为目标物,评价了graphene-TiO2催化剂的光催化性能.结果表明,graphene-TiO2的光催化降解能力明显优于相同方法制备的纳米TiO2颗粒,且具有较好的稳定性,空穴在降解过程中起主要作用,碱性溶液更有利于催化剂对MB的降解.     

Improving the Photocatalytic Activity of Modified Anatase TiO2 with Different Concentrations of Aluminum under Visible Light: Mechanistic Survey

Visible light‐driven Al‐doped TiO₂ with different aluminum contents (2, 5 and 10 mol%) were synthesized via a facile sol–gel method. Fourier transform infrared (FTIR), UV‐visible diffuse reflectance, energy dispersive X‐ray (EDX) spectroscopy as well as X‐ray diffraction (XRD), X‐ray fluorescence (XRF) and scanning electron microscopy (SEM) methods were used for the characterization of the obtained nanoparticles. The photocatalytic performance of the samples was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The yield of the degradation RhB was estimated to be 71%, 89%, 65% and 56%, for the bare TiO₂, 2%, 5% and 10% Al‐doped TiO₂, respectively. It was found that 2 mol% of Al‐doped TiO₂ shows the best photocatalytic performance. In low concentration of dopant, separation of photogenerated electron–hole pairs promoted, and subsequently, the degradation efficiency increased. It was proposed that the degradation of RhB by 2 mol% Al‐doped TiO₂ photocatalyst follows both N‐deethylation and chromophore cleavage mechanisms, while the N‐deethylation still predominated over cleavage of dye chromophore structure. The key role of hydroxyl radicals in RhB degradation was verified by the effects of scavengers. In addition, the photocatalyst can be reused for three runs without any significant loss of its catalytic activity.     

原位稀土修饰Bi_2MoO_6高效可见光催化剂

采用原位法制备了系列稀土离子修饰的Bi2MoO6可见光催化剂并应用于罗丹明B的光催化降解,HPLC-MS显示该反应经脱除乙基的过程形成5个中间产物,最后完全矿化。研究表明,Gd3+修饰效果最佳,且原位法优于浸渍法,主要归因于Gd3+进入Bi2MoO6晶格,形成施主能级,导致能级带隙变窄,不仅有利于可见光活化光催化剂,而且阻碍电子-空穴复合并抑制修饰剂流失,从而提高光催化活性和稳定性。     

可见光诱导的TiO2界面光化学过程

环境污染与防治是当前全球普遍关注的重要课题,环境恶化已成为制约我国可持续发展战略的一个重要环节,治理污染已刻不容缓,因此探索和研究经济有效的消除环境污染物的新技术和新方法具有重要的意义和应用前景.TiO2半导体光催化由于具有生物降解所无可比拟的速度快、无选择性、降解完全等优点,又在价廉、无毒、可以长期使用等方面明显优于传统的化学氧化方法,已成为国内外研究的热点.本论文主要进行了利用可见光诱导染料(或表面络合物)敏化TiO2降解有机污染物(包括染料污染物和有毒有机小分子污染物)的研究,为利用可见光或太阳光敏化半导体处理或预处理有毒有机染料污染物提供了理论基础,主要结果如下:     

原位稀土修饰Bi2MoO6高效可见光催化剂

采用原位法制备了系列稀土离子修饰的Bi₂MoO₆可见光催化剂并应用于罗丹明B的光催化降解,HPLC-MS显示该反应经脱除乙基的过程形成5个中间产物,最后完全矿化。研究表明,Gd³⁺修饰效果最佳,且原位法优于浸渍法,主要归因于Gd³⁺进入Bi₂MoO₆晶格,形成施主能级,导致能级带隙变窄,不仅有利于可见光活化光催化剂,而且阻碍电子-空穴复合并抑制修饰剂流失,从而提高光催化活性和稳定性。     

CeO2/TiO2光催化剂的制备及其可见光脱氮性能

采用溶胶-凝胶和浸渍掺杂两步法合成了CeO₂/TiO₂光催化剂,并对催化剂的理化结构进行表征分析;以吡啶-正辛烷体系为模拟油品氮源,研究了该催化剂在可见光作用下的光催化脱氮行为,并探究了光催化脱氮的最佳反应条件。 结果表明,掺杂的铈主要以CeO₂的形式存在,且增强了催化剂在可见光区的吸收;在可见光辐照150 min的条件下,铈的掺杂量质量分数为8%,所制备的CeO₂/TiO₂催化剂投入量为1.0 g/L时,模拟油品中吡啶的脱氮率高达76.45%。     

Photo and Chemical Reduction of Copper onto Anatase‐Type TiO2 Nanoparticles with Enhanced Surface Hydroxyl Groups as Efficient Visible Light Photocatalysts

In this study, the photocatalytic efficiency of anatase‐type TiO₂ nanoparticles synthesized using the sol–gel low‐temperature method, were enhanced by a combined process of copper reduction and surface hydroxyl groups enhancement. UV–light‐assisted photo and NaBH₄‐assisted chemical reduction methods were used for deposition of copper onto TiO₂. The surface hydroxyl groups of TiO₂ were enhanced with the assistance of NaOH modification. The prepared catalysts were immobilized on glass plates and used as the fixed‐bed systems for the removal of phenazopyridine as a model drug contaminant under visible light irradiation. NaOH‐modified Cu/TiO₂ nanoparticles demonstrated higher photocatalytic efficiency than that of pure TiO₂ due to the extending of the charge carriers lifetime and enhancement of the adsorption capacity of TiO₂ toward phenazopyridine. The relationship of structure and performance of prepared nanoparticles has been established by using various techniques, such as XRD, XPS, TEM, EDX, XRF, TGA, DRS and PL. The effects of preparation variables, including copper content, reducing agents rate (NaBH₄ concentration and UV light intensity) and NaOH concentration were investigated on the photocatalytic efficiency of NaOH‐modified Cu/TiO₂ nanoparticles.     

高效Ag@AgBr等离子体光催化剂的制备及可见光活性研究

采用水热法和光致还原法制备了具有等离子体共振效应的Ag@AgBr可见光催化剂,利用XRD,SEM,EDX,DRS和XPS等手段对产物的结构和性能进行表征,并研究了催化剂在可见光下对罗丹明B(RhB)的光催化降解性能,考察了催化剂的循环使用及捕获剂对Ag@AgBr光催化性能的影响.结果表明:贵金属Ag纳米粒子的表面等离子体共振效应可显著增强Ag@AgBr对可见光的吸收;催化剂对罗丹明B具有较高的可见光降解活性和稳定性,在可见光下照射90 min,对罗丹明B的降解率达95%以上,光催化剂循环使用5次仍具有良好的光催化降解活性;淬灭实验表明在Ag@AgBr降解罗丹明B过程中,吸附在催化剂表面的h+、·OH、O2·-是主要的活性物种.