Ag/TiO2聚丙烯负载膜的制备及其光催化与抗菌特性研究

以聚丙烯负载二氧化钛膜为载体,在一定浓度的AgNO3水溶液中,利用光还原在氧化钛膜表面还原Ag,制备载银二氧化钛负载膜,在室光和太阳光下,分别选择Ag/TiO2聚丙烯膜、TiO2聚丙烯膜和活性炭聚丙烯膜,研究膜的抗菌特性和光催化特性.结果表明:Ag/TiO2负载膜由于同时具有Ag和TiO2的双重效用,显示了良好的杀菌特性,无论是在室内还是太阳光下,都没有检测到活的微生物;在水溶液中检测Ag/TiO2负载膜和TiO2负载膜的光催化特性,发现由于银离子的催化活性中心的作用,光催化降解甲基橙的能力与TiO2负载膜相比,能够提高10%左右,显示了良好的光化学特性.     

硫化镉晶体结构形态对乙醇光催化脱氢活性的影响

有关醇类水溶液光催化贮能脱氢反应研究大多集中在提高半导体TiO₂和CdS表面修饰组分的光催化活性^[1～3]及考察TiO₂半导体晶体结构与光催化性能的关系上^[4,5],CdS半导体晶体结构形态对光催化性能的影响尚未见报道.本文在这方面进行了一些有益的研究.     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

TiO2负载型催化剂及光催化还原CO2反应的表面光电压谱研究

半导体TiO₂作为光催化剂,已被广泛应用于光催化废水处理及光催化储能^[1,2]等方面的研究.人们不断开发高活性的新型光催化剂并对其反应机理进行了探索性研究^[3],希望通过表面负载Pd、Ru、Pt或Rh等贵金属的小岛式颗粒以传递光生电子(或光生空穴).     

紫外光照射下ZnO超微粒子表面上的光反应

由于半导体超微粒子具有独特的尺寸量子化效应和表面效应^[1~6],它在利用太阳能光催化降解有机污染物,有机光合成及光电转化等领域中有着极其广泛的应用.目前,大量的工作集中在超微颗粒表面上有机物的光反应过程的研究^[7].     

高效抗菌Cu2+-壳聚糖季铵盐/丙烯酸复合物的制备

以过硫酸铵为引发剂,在壳聚糖季铵盐（HACC）上接枝丙烯酸（AAc）并络合Cu²⁺,制备了具有高效抗菌性能的HACC-g-PAAc-Cu²⁺复合物.采用红外光谱（FTIR）和核磁共振波谱（¹H NMR）表征了壳聚糖季铵盐接枝改性前后的化学结构变化;利用紫外-可见吸收光谱（UV-Vis）、Cu²⁺选择电极和热失重分析（TGA）表征了壳聚糖季铵盐接枝前后负载Cu²⁺的能力;测定了HACC-Cu²⁺和HACC-g-PAAc-Cu²⁺对金黄色葡萄球菌及大肠杆菌的最小抑菌浓度,并对小鼠经口摄入毒性和兔皮肤敷涂刺激性进行了考察.研究结果表明,在壳聚糖季铵盐上负载Cu²⁺能够有效提高其抗菌性;接枝丙烯酸能提高HACC负载Cu²⁺的能力和抗菌性,Cu/HACC结构单元的摩尔比由接枝前的3：7提高到接枝后的1：1;对金黄色葡萄球菌的最小抑菌浓度由60 mg/L下降到9.2 mg/L,对大肠杆菌的最小抑菌浓度由37 mg/L下降到6.3 mg/L,无摄入毒性和皮肤刺激性.     

化学法沉积银岛膜上的表面增强拉曼散射(Ⅰ)

用银镜反应在抛光的石英片上沉积银膜,经扫描电镜研究表明,控制反应条件可得到表面粒度为50～140nm的SERS活性银岛膜表面,将此活性表面直接插入含微量孔雀石绿水溶液中,测量吸附孔雀石绿分子的拉曼光谱,可获得10⁵倍的拉曼增强,孔雀石绿浓度小到10^-10mol/L时,仍能得到明确的光谱信息,给出了浓度与强度的关系,讨论了吸附作用对几个重要振动带的影响。     

TiO2纳米粒子膜的表面态性质及其光催化活性的研究

TiO₂纳米粒子膜催化剂光催化降解水中污染物,与粉末相比具有可重复使用、易回收等优点,近年来,在光化学领域受到人们的高度重视^[1～3].膜催化剂的表面性质与其光催化活性直接相关,研究这些性质能够为研制、开发高效催化剂提供理论依据.本文采用TiCl₄水解法,制备了酸性、碱性条件下TiO₂纳米粒子膜.利用原子力显微镜(AFM)、X-射线衍射谱(XRD)、红外光谱(IR)和场诱导表面光电压谱(EFISPS)测定其表面微结构.考察了它们对苯酚降解的光催化活性,讨论了膜催化剂的表面性质对光催化活性的影响.     

玻碳电极表面复合配位银电结晶机理研究

以具有实际应用价值的复合配位体系无氰镀银电解液为研究对象, 运用循环伏安和电位阶跃等实验方法, 结合 Scharifker-Hill 经典理论模型分析, 成功获得了Ag在玻碳电极（GCE）表面电沉积的成核机理及成核动力学参数, 并分析了温度对成核方式及成核动力学参数的影响. 结果表明, 该体系下Ag在GCE表面的电沉积是由扩散控制的不可逆过程, 遵循三维瞬时成核生长机理. 随着阶跃电位从-750 mV 负移至-825 mV, 峰值还原电流Im逐渐增大, 达到峰值还原电流所需时间tm逐渐缩短; 扩散系数D变化不大, 基本稳定在（7.61±0.34）×10^-5 cm²·s^-1; 成核密度数N₀则从3.26 ×10⁵ cm^-2提高至10.2×10⁵ cm^-2. 银沉积初期的形貌观察, 验证了其三维瞬时成核生长机理. 提高温度可以显著改善电解液中具备活性的银配位离子的扩散能力, 缩短成核时间, 提升成核密度数N0.     

三维网状Dy3+:YVO4/TiO2复合纤维的制备及光催化产氢性能

以电纺TiO₂纳米纤维为基质, 柠檬酸为软模板, 采用一步水热法制备了具有三维立体网状结构的稀土Dy ³⁺掺杂YVO₄/TiO₂复合纤维. 通过X射线衍射、 扫描电子显微镜、 X射线光电子能谱、 N₂吸附-脱附、 紫外-可见漫反射光谱及荧光光谱等手段对材料的组成、 表面形貌和性能进行表征, 以光分解水产氢实验考察其光催化活性. 结果表明, Dy ³⁺∶YVO₄纳米枝与TiO₂纳米纤维相互交联构筑的纳米纤维网具有大比表面积, 可提供更多活性位点, 改善了多相光催化反应的传递过程; 稀土Dy ³⁺掺杂的YVO₄与TiO₂复合形成异质结相互促进, 在拓宽光谱响应范围、 提高太阳光利用率的同时使光生电子-空穴对得到较好分离, 从而提高了样品的光催化活性. 模拟太阳光照射下, Dy ³⁺∶YVO₄/TiO₂复合纤维光催化产氢速率达到8.63 mmol· h ^-1·g ^-1, 是纯TiO₂纳米纤维的10倍.     

Apatite-forming ability of titanium compound nanotube thin films formed on a titanium metal plate in a simulated body fluid

We compared the apatite-forming ability of a sodium titanate nanotube thin film, an anatase-type titanium dioxide nanotube thin film, and a silver nanoparticle/silver titanate nanotube nanocomposite thin film, in simulated body fluid. The ability of the silver nanoparticle/silver titanate nanotube nanocomposite thin film is slightly higher than that of the anatase-type titanium dioxide nanotube thin film and significantly higher than that of the sodium titanate nanotube thin film. The high ability of the silver nanoparticle/silver titanate nanotube nanocomposite thin film is a newly observed phenomenon, which is probably due to the crystal structure of silver titanate – specifically, to the surface atomic arrangement, the large amount of Ti–OH formed on the nanotube surface, or both. The anatase-type titanium dioxide nanotube thin film and the silver nanoparticle/silver titanate nanotube nanocomposite thin film may have bright prospects for future use in implant materials such as artificial joints. The silver nanoparticle/silver titanate nanotube nanocomposite thin film is particularly promising for its antibacterial properties.     

Low Temperature Sol-Gel Processed Photocatalytic Titania Coating

Transparent thin film coatings of sol-gel derived titanium dioxide were produced on cotton fabrics at a low temperature of 150°C. The photocatalytic activity of the formed layers was studied by means of their antibacterial property. SEM images show the formation of continuous layers of titanium dioxide with grains of about 20 nm in diameter. The UV-blocking effect of titania coatings was also studied. XRD patterns revealed the existence of anatase phase in a small scale within the titania layers.     

Improved visible light photocatalytic activity of titania loaded with silver on discoloration of a heterocyclic aromatic chemical dye solution

The photocatalytic activity of silver deposited Degussa P25 titanium dioxide (Ag-DP25) in the photodegradation of methylene blue (MB) was investigated. The as-prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), infrared spectra and surface photovoltage spectroscopy (SPS) techniques. The obtained results show that the silver dopant could effectively inhibit the recombination of the photoinduced electron and holes, improving the absorption capability for visible light of photocatalyst and leading to increased surface OH group density. The degradation experiment reveals that the catalytic property of Ag-DP25 in the degradation of MB dye is more efficient than that of commercially available Degussa P25 TiO₂ (DP25) samples under visible-light irradiation. Besides, degradation kinetics of MB dye can, be well described by Langmuir-Hinshelwood equation and shows pseudo-first order law.     

Effect of Pt loading on the photocatalytic reactivity of titanium oxide thin films prepared by ion engineering techniques

Platinum-loaded titanium oxide thin-film photocatalysts were prepared by using an ionized cluster beam (ICB) deposition method and a RF magnetron sputtering (RF-MS) deposition method as dry processes. From the results of the photocatalytic oxidation of acetaldehyde with O₂ under UV light irradiation, small amounts of Pt loading (less than 10 nm film thickness) were found to dramatically enhance the photocatalytic reactivity. However, when TiO₂ thin films were loaded with relatively larger amounts of Pt (more than 30 nm as the film thickness), the photocatalytic reactivity became lower than for the pure TiO₂ thin films. Moreover, investigations of the ratio of Pt loaded onto the surface of the thin film catalysts by XPS measurements revealed that the small amounts of Pt loaded exist as very small clusters working to efficiently enhance the charge separation, whereas, large amounts of Pt covers the entire surface of the TiO₂ thin films, resulting in a decrease of the photocatalytic reactivity.     

Flame-retardancy and photocatalytic properties of cellulosic fabric coated by nano-sized titanium dioxide

We have investigated the effect of titanium dioxide as a durable finish on the flammability and photocatalytic self-cleaning of cellulosic fabric. Nano-sized titanium dioxide particles were successfully synthesized and deposited onto cellulosic fibers with good compatibility, significant photocatalytic self-cleaning activity, and flame-retardancy properties using the sol–gel process at low temperature. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under ultraviolet–visible illumination, and also flame-retardancy effect was tested by flammability tester. The samples have been characterized by several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction, and thermogravimetric analysis. The titanium dioxide nanoparticles with 10–20 nm in size have been found to form a homogeneous thin film on the fiber surface which shows efficient photocatalytic and flame-retardancy properties. This preparation technique can also be applied to new fabrics to create self-cleaning and flame-retardancy properties in them.     

Ag改性纳米ZnO薄膜及光催化活性

采用溶胶-凝胶法和光还原沉积贵金属法结合制备出Ag改性的纳米ZnO薄膜。利用FESEM、XPS、ESR、UV-Vis分析了纳米Ag-ZnO薄膜的表面形貌、表面组成和光谱特征。FESEM分析表明银在纳米ZnO薄膜表面形成原子簇而没有形成均匀覆盖层。XPS分析表明负载在纳米ZnO薄膜表面的银以Ag⁰形式存在; 相对于纳米ZnO薄膜, 纳米Ag-ZnO薄膜中晶格氧的含量有所下降,而表面羟基氧和吸附氧的含量显著增加。纳米Ag-ZnO薄膜的ESR峰强比纳米ZnO薄膜大,表明纳米Ag-ZnO薄膜中束缚单电子的氧空位的浓度高于纳米ZnO薄膜。UV-Vis分析纳米Ag-ZnO薄膜的紫外可见吸收光谱可能是纳米银粒子与纳米ZnO薄膜共同作用的结果。以甲基橙为模拟污染物,考察了纳米Ag-ZnO薄膜的光催化活性以及银沉积量对催化剂活性的影响。光催化降解结果表明,银的沉积量为0.018 2 mg·cm^-2的纳米Ag-ZnO薄膜的光催化活性最高,在紫外光照射3 h后甲基橙降解率约为78%,而纳米ZnO薄膜约为62%。     

二氧化钛功能薄膜研究发展与应用

二氧化钛薄膜在紫外光照射下的光催化活性和亲水性吸引了许多科学工作者对其进行了大量的研究.本文对近年来二氧化钛功能薄膜的研究发展与应用作了简要介绍,同时也对研究中存在的问题和将来研究发展的方向进行了简单评述.     

二氧化钛薄膜的液相沉积法制备研究

常温下,采用锐钛矿型二氧化钛纳米晶为诱导剂,采用液相沉积法制备了二氧化钛薄膜,采用XRD、SEM、AFM对其晶型、平均晶粒尺寸和形貌进行表征。结果表明,室温所制的二氧化钛薄膜为锐钛矿型,平均粒径为5．8nm,二次粒子平均粒径为10nm,薄膜上观察不到明显的孔洞和裂纹,表面均匀平整,以苯酚的光催化氧化作为目标反应,评价了二氧化钛薄膜的光催化活性。     

海绵状纳米结构TiO2膜的制备及其光催化活性

采用电化学阳极氧化法在钛表面构筑了海绵状纳米结构TiO2膜. 应用扫描电子显微镜(SEM)和X射线衍射(XRD)对膜层的形貌和晶型进行了分析和表征, 考察了阳极氧化时间对膜层厚度的影响, 并通过海绵状纳米结构TiO2膜对甲基橙的光催化降解研究了膜层厚度与光催化活性的关系. 结果表明, 海绵状纳米结构TiO2膜对甲基橙具有光催化降解作用, 而且随着膜层厚度的增加, 光催化降解速率显著增大, 厚度为2.2 μm的海绵状纳米结构TiO2膜对甲基橙的光催化降解速率是厚度为480 nm的6.4倍.