超声波激活纳米氧化锌损伤牛血清白蛋白的研究

利用紫外-可见(UV-Vis)光谱和荧光光谱研究了超声波照射激活纳米氧化锌(ZnO)粒子对牛血清白蛋白(BSA)的损伤,并考查了超声波照射时间、纳米ZnO粉末加入量、溶液酸度和照射功率等因素对BSA分子损伤的影响。结果表明,对于体系温度为37.0±0.2 ℃和浓度为1.0×10^-5 mol·L^-1的BSA溶液,BSA的损伤程度随着超声波照射时间,纳米ZnO粉末加入量,溶液pH值和照射功率的增加而增大。此外,还初步探讨了超声波照射激活纳米ZnO粒子损伤BSA分子的机理,认为是声致发光和高热激发使纳米ZnO粒子产生·OH自由基,进而损伤BSA分子。     

TiO2纳米纤维无纺布的制备及光催化性能研究

以聚乙烯吡咯烷酮(PVP)作为配位剂与钛酸正丁酯(Ti(C₄H₉O)₄)反应制得前驱体，再以乙醇为溶剂，CH3COOH作为催化剂，采用静电纺丝法制得PVP/TiO₂复合纳米纤维，经550 ℃、700 ℃和900 ℃焙烧后分别得到以锐钛矿型的TiO₂为主、以金红石型TiO₂为主和完全金红石晶型的TiO₂纳米纤维。对所制得的纳米纤维的结晶度、纯度和形貌，分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)等进行了表征。光降解苯酚水溶液的实验结果表明，550 ℃下煅烧得到的以锐钛矿占主体的TiO₂纳米纤维，2 h使浓度为50 mg·L^-1苯酚水溶液的降解率超过85%，这充分说明这种TiO₂电纺纳米纤维具有良好的光催化性能。     

晶相组成可调的高活性可见光应答型二氧化钛纳米复合光催化材料的制备

采用新的化学溶液法,通过不同体积的钛酸四异丙酯的2-乙二醇单乙醚溶液与一定浓度的H₂O₂水溶液直接反应并对生成的钛过氧化配合物进行焙烧,制备了一系列TiO₂光催化剂. 表征发现,所得TiO₂样品为金红石和锐钛矿的纳米复合晶体,改变2-乙二醇单乙醚的体积可实现金红石相比例在0~96%广范围的调变.与商业二氧化钛P-25相比,所得的TiO₂紫外-可见光吸收谱出现明显红移,间隙能降低, 在可见光照射下,该样品对亚甲基蓝有良好的降解活性. 当2-乙二醇单乙醚的添加量为5 ml时,所得样品体相中金红石相比例接近50%,其光催化活性和吸附性能最好,可分别是P-25的3倍和5倍. 拉曼光谱结合X射线衍射等表征结果表明,该样品的表面仅含少量的金红石相. TiO₂纳米复合晶表面晶相的组成和分布对其光催化降解亚甲基蓝的活性及其吸附能力有直接的影响. 另外,TiO₂纳米复合晶的缺陷浓度也是增强其光吸收能力,提高其可见光光催化活性的原因之一.     

SnCl4对纳米二氧化钛晶相结构的低温转变控制研究

采用二种方法制备了低温下晶相结构可控制转变的纳米二氧化钛。一种方法是采用乙醇作溶剂的溶胶-凝胶法,通过控制SnCl₄的添加量,便可在450℃热处理下实现纳米TiO₂从纯锐钛矿到不同比例的复合相直至纯金红石相的转变。另一种方法是采用钛酸丁酯为原料直接低温水解,通过加入不同量的SnCl₄,制备了具有晶态结构的二氧化钛复合溶胶,在120℃下干燥处理便可实现TiO₂从锐钛矿到不同比例的复合相(金红石型、锐钛矿型和板钛矿型)直至纯金红石相的转变,制备所需晶态结构的纳米TiO₂。所有样品进行了透射电镜与XRD表征,制备的纳米TiO₂及其TiO₂-SnO₂纳米复合材料颗粒小、分布均匀、分散性好,没有检测到SnO₂晶体的X-衍射特征峰。     

V2O5-TiO2复合半导体光催化材料结构及光响应性能研究

采用溶胶凝胶法制备了V₂O₅-TiO₂复合半导体材料，通过Raman、XRD及UV-Vis DRS等实验方法研究了V₂O₅与TiO₂复合对材料表面组成、晶体结构以及光响应性能的影响。结果表明：钒加入后优先与TiO₂作用形成较为稳定的金红石型TiVO₄晶相，其中V⁴⁺是促进TiO₂发生相变的关键；随着钒加入量的增加，V₂O₅由表面高分散状态逐渐聚集形成晶相，并释放部分Ti⁴⁺使之形成锐钛矿型TiO₂晶相，使得体相中金红石型TiO₂的含量有所下降；复合后形成的TiVO₄晶相显著提高了材料对可见光的吸收率，并使其吸光域红移至460 nm左右。     

纳米TiO2的制备及对三甲胺气体的敏感性能

用硬脂酸凝胶法制备纳米TiO₂材料,并用XRD、TEM、IR对纳米晶的晶型、晶粒大小及形貌进行表征；用XPS分析不同晶型的纳米TiO₂表面吸附氧的情况，发现锐钛矿型纳米TiO₂比金红石型纳米TiO₂有较多的表面吸附氧. 检测了不同晶型纳米TiO₂对三甲胺（TMA）气体的敏感性能.结果表明锐钛矿型纳米TiO₂对TMA有较高的灵敏度. 对敏感性能的机理进行了讨论.     

纳米TiO2低温水解法的晶型控制合成及其表面织构的研究

分别以TiCl₄，Ti(NO₃)₄和Ti(SO₄)₂为前驱体，在低温和强酸性条件下，通过水解反应可控地合成了具有不同晶相组成，且比表面积较高的纳米TiO₂，并用XRD，TEM和N₂^-吸附脱附技术对其晶相、粒径大小、形貌及比表面积进行了表征。结果表明，钛离子在有Cl^-、NO₃^-存在的酸性溶液中水解，水解温度≤80 ℃，可以生成结晶良好的具有细小晶粒尺寸和较高比表面积的金红石型纳米TiO₂粉体，水解温度>80 ℃，反而有锐钛矿型TiO₂生成，而在有SO₄^2-存在的酸性溶液中，TiO₂样品的晶相组成不随水解温度的变化而改变，均为锐钛矿型，其比表面积可达300 m²·g^-1。     

不同pH值制备的TiO2和TiO2/SiO2催化剂结构、表面性质及光催化活性

以TiOSO₄和SiO₂溶胶为原料, 采用沉淀法用氨水调节pH值制备TiO₂和TiO₂/SiO₂催化剂. 制备的催化剂用X射线衍射(XRD), 扫描电镜(SEM), N₂吸附(BET), 紫外-可见(UV-Vis)漫反射光谱, 程序升温脱附(NH₃-TPD), 傅里叶变换红外(FT-IR)光谱技术分析. XRD谱图显示纯TiO₂中锐钛型和金红石相共存, 且金红石相含量随pH值升高而增加. 但是, TiO₂/SiO₂催化剂只有锐钛型. 扫描电镜发现制备的催化剂呈类球形, 颗粒间相互交叠, 粒径在10-25 nm之间. TiO₂和TiO₂/SiO₂光催化剂的比表面积随pH值升高略有增大. SiO₂的添加会增大催化剂的比表面积. 程序升温脱附实验结果说明催化剂的表面酸量随pH值升高而增加. TiO₂/SiO₂的表面酸量比相同pH值制备的TiO₂大. 红外光谱分析说明Si掺杂和高pH值有利于催化剂表面生成更多的羟基. TiO₂和TiO₂/SiO₂光催化剂的催化活性随pH值升高而明显增强. TiO₂/SiO₂的光催化活性优于TiO₂. TiO₂/SiO₂催化剂具有较好的耐久性.     

室温合成金红石TiO2及其在染料敏化太阳能电池中的应用

以钛酸四丁酯为前驱体, 在室温下通过水解沉淀法合成了金红石型TiO₂纳米粒子; 用X射线衍射(XRD)研究了反应温度、酸度以及酸的种类对形成TiO₂晶型的影响. 实验结果表明, 高酸度、低温度以及Cl-有助于金红石相的生成. 在相同条件下加入一定量P105 (EO₃₇PO₅₆EO₃₇)三嵌段聚合物制备出一种金红石型粗糙聚集球. 扫描电子显微镜(SEM)结果表明这种粗糙聚集球直径大约350 nm, 比表面积测试(BET)及紫外漫反射测试发现粗糙球在保持较大比表面积的同时有散射效应. 此粗糙球与20 nm TiO₂粒子以质量比1:4混合作为工作电极的散射层并应用于染料敏化太阳能电池, 电池效率达到7.27%, 较不加粗糙球的效率提高17%; 我们认为这是因为在保持工作电极染料吸附量基本不变的条件下粗糙球提高光散射性能.     

SO42-改性后的TiO2(锐钛和/或金红石)表面上MoO3的分散性质研究

采用红外(IR)、拉曼(Raman)、X-射线衍射(XRD)、程序升温还原(TPR)等方法考察了经硫酸根改性后的金红石(SR)与锐钛矿(SA)的混合比例变化时的负载型催化剂，MoO₃ / TiO₂(SR+SA)，的一些物理化学性质(如活性组分MoO₃的分散行为、表面酸碱性、氧化还原性)的变化规律。结果表明：对于MoO₃ / TiO₂(SR+SA)样品，低含量MoO₃表面分散时倾向于优先与混合载体中的改性金红石(SR)发生作用；TiO₂载体表面SO₄^2-的存在，使得载体表面产生了新的酸性位，导致样品中表面分散的钼物种主要以聚合八面体状态存在。     

Catalytic damage of bovine serum albumin by metronidazole under ultrasonic irradiation in the presence of nano-sized TiO2 powder

In previous work, it was found that the bovine serum albumin (BSA) could obviously be damaged by nano-sized TiO₂ powder as a sonocatalyst under ultrasonic irradiation. In this work, metronidazole (MTZ) was adopted as a sensitizer to intensify the damage of BSA molecules. It was found that the damage degree of BSA molecules in the presence of MTZ was more serious than in the absence of MTZ. That is, under ultrasonic irradiation combined with nano-sized TiO₂ powder, the addition of MTZ could remarkably aggravate the damage to BSA molecules. Meanwhile, the damage degree was also affected by some influence factors, such as ultrasonic irradiation time, ultrasonic irradiation power, MTZ concentration, solution acidity, ionic strength and solution temperature. In addition, the damage site of BSA molecules was also estimated by synchronous fluorescence spectra. It was found that the damage site of BSA molecules was mainly at tyrosine (Tyr) residue.     

转晶纳米TiO2的制备及其声催化活性的研究

近几年兴起的半导体多相光催化技术在有机废水处理方面受到了人们的普遍关注[1,2]。众多的半导体光催化剂材料中,TiO2因其化学性质稳定和催化效率高而倍受青睐[3,4]。在紫外光的照射下,TiO2与H2O产生具有极强氧化能力的HO·自由基,最终可使废水中的有机物完全降解生成CO2,H2O以     

Photodegradation of dye pollutants on one-dimensional TiO2 nanoparticles under UV and visible irradiation

Titanium dioxides (TiO₂) nanoparticles with one-dimensional (1D) geometry, nanorods and nanostripes, were used as photocatalysts to photodegrade Rhodamine B (RhB) under ultraviolet (UV) and visible irradiation. The nanorods catalyst exhibited very interesting photocatalytic properties: under the UV irradiation its catalytic activity was slightly below that of the well-known TiO₂ catalyst P25, while under visible light it exhibited a better activity than P25.This fact indicates that the nanorods have a superior ability to utilize less energetic but more abundant visible light. Moreover, the 1D TiO₂ nanoparticles can be readily separated from aqueous suspensions by sedimentation after the reaction. With these advantages the 1D TiO₂ catalysts have a great potential for environmental applications. Various analytical techniques were employed to characterize TiO₂ catalysts and monitor the photocatalytic reaction. It was found that the catalytic performance of the catalysts is greatly dependent on their structures: The superior activity of P25 (consists of anatase and rutile nanocrystals) under UV light results probably from the interfacial interaction between anatase and rutile nanocrystals in this solid, which do not exist in the nanorods (only anatase). The titanate nanostripes (titanate) can absorb UV photons with shorter wavelength only.     

Synthesis of Mixed-Phase TiO<Subscript>2</Subscript> Nanopowders Using Atmospheric Pressure Plasma Jet Driven by Dual-Frequency Power Sources

Mixed-phase TiO₂ nanopowders with different ratios of anatase and rutile have been successfully synthesized using atmospheric pressure plasma jet driven by dual-frequency power sources. The crystal structures of the TiO₂ nanopowders were characterized by X-ray diffraction, SAED, HRTEM, and Raman shift spectroscopy. These results indicated that samples possessed anatase and rutile structure, in addition, the crystallinity of the TiO₂ nanopowders increased and the chlorine contamination decreased with discharge RF power increasing. The photocatalytic activity of the TiO₂ nanopowders was evaluated by decomposition methylene blue solution. The TiO₂ nanopowders which were produced at the discharge RF power of 110 W had the highest photocatalytic activity. Optical emission spectroscopy (OES) was used to detect various excited species in the plasma jet. The results indicate that the various RF power significantly changes the intensities of emission lines (Ar, Ar⁺, Ti, Ti⁺, Ti²⁺, Ti³⁺ and O), which results in the TiO₂ nanopowders a mixture of anatase and rutile phases. The nonequilibrium chemical composition could be formed in one step without anneal. It may have potential applications for synthesizing nanosized particles of high crystallinity by reactive nonthermal plasma processing.     

Hydrogenated Anatase: Strong Photocatalytic Dihydrogen Evolution without the Use of a Co‐Catalyst

The high‐pressure hydrogenation of commercially available anatase or anatase/rutile TiO₂ powder can create a photocatalyst for H₂ evolution that is highly effective and stable without the need for any additional co‐catalyst. This activation effect cannot be observed for rutile; however, for anatase/rutile mixtures, a strong synergistic effect can be found (similar to results commonly observed for noble‐metal‐decorated TiO₂). EPR and PL measurements indicated the intrinsic co‐catalytic activation of anatase TiO₂ to be due to specific defect centers formed during hydrogenation. These active centers can be observed specifically for high‐pressure hydrogenation; other common reduction treatments do not result in this effect.     

Preparation of nanocrystalline TiO<Subscript>2</Subscript> powders for photocatalytic oxidation of phenol

Nanocrystalline TiO₂ powders in the anatase, rutile, and mixed phases prepared by hydrolysis of TiCl₄ solution were of ultrafine size (<7.2 nm) with high specific surface areas in the range 167 to 388 m²/g. In the photocatalytic degradation of phenol as model reaction, the photocatalytic properties of TiO₂ nanoparticles were evaluated by use of UV–vis absorption spectroscopy and total organic carbon (TOC) content. The synthetic mixed-phase TiO₂ powder calcined at 400 °C had higher activity than pure anatase or rutile; it degraded more than 90% phenol to CO₂ (evaluated by TOC) after irradiation with near UV light for 90 min at a catalyst loading of 0.4 g/L. The TOC results indicated that rutile TiO₂ crystallites of particle size 7.2 nm resulted in much better photocatalytic performance than particles of larger size. This result suggested that some intermediates, not determined by UV–vis absorption spectroscopy, existed in the solution after the photocatalytic process over the rutile TiO₂ photocatalysts of larger crystallite size.     

Sonocatalytic damage of solute bovine serum albumin by disperse ZnO/porcine dens composite under ultrasonic irradiation

ZnO/Dens composite were prepared with nano-sized ZnO and porcine dens powders by mechanical mixing, liquid boiling, ultrasonic dispersion and heat-treated at 500°C for 50 min. The samples were characterized by X-ray diffraction (XRD) and its sonocatalytic activity was evaluated by the damage of bovine serum albumin (BSA). Furthermore, the effects of ultrasonic irradiation time, ZnO/Dens composite amount, solution acidity and ionic strength on the sonocatalytic damage of BSA were evaluated. The results show that the damage degree of BSA aggravated with the increase of ultrasonic irradiation time, ZnO/Dens composite amount and ionic strength, but weakened with the increase of solution acidity. In addition, the damage site to BSA molecules was analyzed by synchronous fluorescence spectra and the results exhibited that the damage site was mainly at tryptophan (Trp) residue. This study should be helpful to drive sonocatalytic method to treat tumors in clinic application.     

Active Sites for Adsorption and Reaction of Molecules on Rutile TiO2(110) and Anatase TiO2(001) Surfaces (cited: 1)

The reactivity of specific sites on rutile TiO₂(110)-(1×1) surface and anatase TiO₂(001)-(1×4) surface has been comparably studied by means of high resolution scanning tunneling microscopy. At the rutile TiO₂(110)-(1×1) surface, we find the defects of oxygen vacancy provide distinct reactivity for O₂ and CO₂ adsorption, while the terminal fivefold-coordinated Ti sites dominate the photocatalytic reactivity for H₂O and CH₃OH dissociation. At the anatase TiO₂(001)-(1×4) surface, the sixfold-coordinated terminal Ti sites at the oxidized surface seem to be inert in both O₂ and H₂O reactions, but the Ti-rich defects which introduce the Ti³⁺ state into the reduced surface are found to provide high reactivity for the reactions of O₂ and H₂O. By comparing the reactions on both rutile and anatase surfaces under similar experimental conditions, we find the reactivity of anatase TiO₂(001) is actually lower than rutile TiO₂(110), which challenges the conventional knowledge that the anatase (001) is the most reactive TiO₂ surface. Our findings could provide atomic level insights into the mechanisms of TiO₂ based catalytic and photocatalytic chemical reactions.     

TiO2纳米管阵列光电催化氧化处理氨氮废水

用电化学阳极氧化法制备了高度有序的钛基二氧化钛纳米管阵列薄膜。用场发射扫描电镜(FE-SEM)、X射线衍射(XRD)表征样品的形貌与晶型特征。以二氧化钛纳米管阵列为光阳极,石墨为对电极,测试了不同pH值和外加偏压条件下的光电流响应和光电催化氧化降解NH4Cl水溶液(以N计,100 mg·L-1)的效率。结果表明:所制备的TiO2纳米管阵列具有锐钛矿和金红石的混晶结构,且主要晶型为锐钛矿。光电流响应的强弱与光电催化氧化效率的高低相对应,降解氨氮废水的最佳条件为pH=11,偏压为1.0 V。     

低频超声波照射下卟啉锰(HP-Mn)配合物对牛血清白蛋白(BSA)损伤的研究

应用紫外-可见(UV-vis)光谱和荧光光谱研究了卟啉-锰(HP-Mn)配合物与牛血清白蛋白(BSA)的相互作用及在超声波作用下HP-Mn对BSA的损伤作用,并探讨了超声波照射时间,HP-Mn浓度,酸度,离子种类和强度等因素对BSA损伤的影响。结果表明,HP-Mn对BSA荧光的猝灭属于静态猝灭,两者主要通过静电作用相互结合,同时也存在着配位作用,作用距离(r)为3.49 nm。另外,在超声波作用下,HP-Mn能够明显损伤BSA。损伤程度随着超声波照射时间的增长,酸度的升高和HP-Mn浓度的增大而增大,但离子种类和强度的影响较为复杂。这一结果为声动力学(SDT)疗法治疗肿瘤应用于临床具有重要的意义。