Ag-TiO2光催化剂的制备、性能及机理研究

采用溶胶-凝胶法制备了Ag-TiO2光催化剂粉体,研究了不同制备条件对样品性能的影响,并以亚甲基蓝(MB)作为目标降解物,研究了其光催化性能,分析了Ag掺杂提高光催化性能的机理。结果表明,Ag离子的掺杂拓展了TiO2在可见光区的光谱响应范围,降低了光生电子和空穴的复合几率;在普通日光灯下,当Ag的掺杂量为n(Ag)∶n(TiO2)=0.1%,热处理温度为400℃条件下制备的样品催化性能最好,其光催化活性显著高于Degussa P25。     

Ag-TiO2负载玻璃纤维的制备及其光催化活性

以玻璃纤维(Glass fiber,GF)为载体,TiOSO4和AgNO3为原料,采用光催化还原法制备了Ag沉积纳米TiO2负载玻璃纤维(Ag-TiO2/GF),并以亚甲基蓝(MB)为目标降解物,考察了Ag-TiO2/GF在太阳光下的光催化活性.分别采用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)及紫外可见吸收光谱(UV-Vis)对其结构和性能进行表征.结果表明,AgNO3的最佳沉积浓度为0.10mol/L,Ag以单质形式沉积于TiO2表面,适量的Ag沉积不仅能抑制TiO2晶粒的生长和团聚,而且能使Ag-TiO2的紫外-可见吸收曲线发生明显的红移.Ag-TiO2/GF在太阳光条件下120min内对亚甲基蓝溶液的降解率为93.0％,其光催化活性高于P25(商业TiO2)和未沉积Ag的样品.     

环境友好型塑料用改性ZnO添加剂的光催化性能研究

以纳米ZnO和AgNO3溶液为原料,采用掺杂的方法制备了改性的塑料用ZnO添加剂,通过其光催化降解亚甲基蓝的效果评价了样品的光催化性能。实验结果表明,当银的掺杂量为2.8%,光催化剂添加浓度是0.8g/L时,此时Ag/ZnO复合粉体对亚甲基蓝的光催化降解效果最好。制备的Ag/ZnO复合粉体在紫外光区和可见光区都有较强的吸收,且吸收峰波长和Ag与纳米ZnO相比都出现了一定程度的红移。掺杂银显著提高了纳米ZnO的光催化性能     

高活性光催化剂纳米Ag-碳纳米管-混晶TiO_2复合纤维的可控制备

为解决TiO_2对太阳能有效利用率低、光生电子与空穴再复合率高、光催化活性低且难回收等应用难题,利用静电纺丝技术成功地制备了纳米Ag-碳纳米管(CNT)-混晶TiO_2复合纤维,并采用SEM、XRD、EDS及Raman等表征方法详细分析了材料的微观结构与组分,研究了纳米Ag-CNT-混晶TiO_2复合纤维对亚甲基蓝的光催化活性。结果表明:锐钛矿与金红石相TiO_2混晶不仅可降低材料的禁带宽度,还能减缓光生电子与空穴的复合淬灭;纳米Ag颗粒的局域表面等离激元共振可增强Ag-CNT-混晶TiO_2复合纤维的光吸收,CNT能促进光生电子与空穴的有效分离;纳米Ag-CNT-混晶TiO_2复合纤维对亚甲基蓝的首次降解率可达97.5%,且5次催化循环后对亚甲基蓝的降解率仍保持在90.0%以上。所得结论表明静电纺丝制备的新型纳米Ag-CNT-混晶TiO_2复合纤维是一种高活性的光催化剂,且容易回收,具有光降解亚甲基蓝的应用前景。     

TiO2薄膜溅射工艺参数对其光催化性能的影响

利用中频交流反应磁控溅射方法制备TiO2薄膜光催化剂,研究了溅射工艺参数对薄膜光催化能力的影响.采用动态反应系统,紫外光源为TUV,降解对象为0.02 mmol/L亚甲基蓝溶液.结果发现:Ar/O2混合反应溅射在O2分压大于9%之后亦可制备出光催化能力与纯O2溅射相近的TiO2薄膜.TiO2薄膜厚度是影响其光催化降解能力的最敏感因素,800 nm以下TiO2薄膜降解能力基本与厚度成正比.TiO2薄膜在黑暗环境下长期放置,光催化性能会出现一定下降,但紫外光预照射可以使其有效恢复.     

钒-氮共掺杂TiO_2/凹凸棒复合光催化材料表征及光催化性能研究

用溶胶-凝胶法制备了钒-氮共掺杂TiO2/凹凸棒复合光催化材料,采用TEM、XRD、BET及UV-Vis漫反射吸收光谱对其性能进行了表征。在模拟太阳光条件下,以亚甲基蓝溶液为目标降解物,对复合光催化材料光催化性能进行评价,复合光催化材料投入到亚甲基蓝溶液中饱和吸附,在40mg/L的亚甲基蓝溶液中,复合光催化材料投加量为1g/L,在800W氙灯下反应6h后,对亚甲基蓝的降解率为84%;重复反应4次,光催化降解变化不大;静置40min后,完成沉降,实现回收。     

Eu~(3+)掺杂纳米TiO_2的制备及催化降解亚甲基蓝的研究

采用溶胶-凝胶法制备了Eu3+掺杂的纳米TiO2粉体,采用X射线衍射(XRD)和荧光光谱分析(PL)等手段对TiO2的相结构和TiO2中电子-空穴对的复合性能进行了表征,探讨了掺杂组分对光催化活性的影响机制。以紫外光下降解亚甲基蓝为探针反应,考察铕的掺杂对催化剂催化性能的影响。结果表明Eu3+的掺杂能够通过抑制催化剂晶粒长大从而减少团聚,并且通过降低光生电子-空穴的复合几率,提高催化剂的光催化活性。光催化实验表明,催化剂加入量为3g/L,亚甲基蓝溶液初始浓度为20mg/L时,掺杂1%Eu3+的催化剂催化性能最佳,反应3.5h降解率达到85.5%。     

磁控溅射制备非晶态TiO2-V薄膜的光催化性能研究

采用磁控溅射方法,在玻璃基片上制备v掺杂非晶态TiO2薄膜,研究了射频掺杂功率、基片温度以及薄膜厚度等因素对薄膜光催化性能的影响.x射线衍射(XRD)及x光电子能谱(XPs)分析表明:薄膜为非晶态,薄膜主要成分为钛(Ti)和钒(V),其比例为8.7:l.光催化降解10mg/L的亚甲基蓝溶液实验表明:随着薄膜厚度的增加,光催化降解率递增,当厚度达129nm时,薄膜对亚甲基蓝的降解率为83.36%.     

纳米TiO2薄膜的低温制备与光谱特性研究

以钛酸丁酯为原料,采用改进溶胶-凝胶法,通过浸渍-提拉工艺在低温条件下制备了锐钛矿纳米TiO2薄膜。利用X射线衍射、紫外-可见光吸收光谱、傅里叶变换红外光谱对所制备的TiO2薄膜的晶型结构和光谱特性进行了分析,并利用紫外光照降解亚甲基蓝溶液来评价所制备薄膜的光催化活性。结果表明:经过陈化和水浴处理后,钛酸丁酯完全水解,所得TiO2薄膜为锐钛矿结构,对紫外光表现出较强的吸收特性。低温水浴处理有利于提高薄膜的光催化活性。     

Ag+/Ag-TiO2纳米空心球制备及其可见光催化性能

在TiO2/聚苯乙烯复合材料表面沉积硫化银,空气中煅烧制备了Ag+/Ag修饰的二氧化钛纳米空心球(Ag+/Ag-TiO2纳米空心球,即Ag+/Ag-HTS)。结果表明,所制备的Ag+/Ag-HTS具有可见光催化降解甲基橙的活性,随着甲基橙的初始浓度降低其催化降解效率提高。肖特基势垒的形成有助于更多的空穴转移到材料的表面,增强其光催化效率;表面的Ag+有助于电子的清除,防止光激电子与光激空穴复合。随着硫化银沉积数量的提高,Ag+/Ag-HTS的可见光催化活性提高,其光催化降解甲基橙的反应具有假一级反应的动力学特征。使用25%Ag+/Ag-HTS光催化剂,在可见光下照射2 h甲基橙降解率高达70.6%。     

Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application

TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag(0) state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm(-2) and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.     

Ag/TiO2薄膜结构和光催化性能研究

采用溶胶-凝胶技术制备了Ag掺杂的TiO2薄膜.用XRD、氮吸附法、UV-VIS-NIR分光光度计以及XPS对Ag掺杂后TiO2薄膜结构的变化进行了分析;用分光光学法通过在紫外光照下分解亚甲基蓝的实验比较了TiO2薄膜与Ag/TiO2薄膜的光催化性能.结果发现,掺杂适量的Ag有助于TiO2薄膜光催化氧化性能的提高,原因在于:（1）Ag通过引入耗尽层提高了TiO2的电荷分离能力,并吸引空穴向薄膜表面移动,结果使薄膜表面空穴的浓度提高,薄膜光催化效率提高;（2）Ag减小了TiO2粒子的粒径,使TiO2禁带宽度增大,薄膜光催化氧化的能力提高;（3）Ag掺杂后,TiO2薄膜表面对-OH基和水的吸附增加,使光照后TiO2薄膜表面活性自由基·OH的浓度增加,空穴向薄膜所吸附物质的转移能力提高.     

Ag/TiO2薄膜结构和光催化性能研究

采用溶胶-凝胶技术制备了Ag掺杂的TiO₂薄膜.用XRD、氮吸附法、UV-VIS-NIR分光光度计以及XPS对Ag掺杂后TiO₂薄膜结构的变化进行了分析;用分光光学法通过在紫外光照下分解亚甲基蓝的实验比较了TiO₂薄膜与Ag/TiO₂薄膜的光催化性能.结果发现,掺杂适量的Ag有助于TiO₂薄膜光催化氧化性能的提高,原因在于:（1）Ag通过引入耗尽层提高了TiO₂的电荷分离能力,并吸引空穴向薄膜表面移动,结果使薄膜表面空穴的浓度提高,薄膜光催化效率提高;（2）Ag减小了TiO₂粒子的粒径,使TiO₂禁带宽度增大,薄膜光催化氧化的能力提高;（3）Ag掺杂后,TiO₂薄膜表面对-OH基和水的吸附增加,使光照后TiO₂薄膜表面活性自由基·OH的浓度增加,空穴向薄膜所吸附物质的转移能力提高.     

Synthesis of beta-cyclodextrin-modified water-dispersible Ag-TiO2 core-shell nanoparticles and their photocatalytic activity

The beta-cyclodextrin-modified Ag-TiO2 core-shell nanoparticles were prepared by sodium borohydrate reduction of AgNO3 and the subsequent hydrolysis of the tetraisopropyl orthotitanate in an aqueous medium. Inversely in the preparation of beta-cyclodextrin-modified TiO2-Ag core-shell nanoparticles, first hydrolysis and then following reduction were carried out. The synthesized spherical core-shell nanoparticles were highly water-dispersible and had an average diameter in the range of 9 to 12 nm. A significant shifting of surface plasmon band was observed for the synthesized Ag-TiO2 and TiO2-Ag core-shell nanoparticles. On a model reaction, namely, the photodegradation of phenol by the UV light irradiation, the photocatalytic property of TiO2 nanoparticles was enhanced, when the Ag nanoparticle was embedded in the core of TiO2 nanoparticles but TiO2 nanoparticles coated by Ag shell decreased the photocatalytic property of TiO2 nanoparticles. The mechanism is ascribed to the surface plasmon characteristics of Ag in the core of the TiO2 nanoparticles under the acceleration by host-guest inclusion characteristics.     

Photocatalytic properties of porous TiO2/Ag thin films

In this study, nanocrystalline TiO₂/Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO₂/Ag thin films were prepared after calcination at a temperature of 500 °C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO₂ films. The as-prepared TiO₂ and TiO₂/Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation.When PS spheres of different sizes were introduced after calcination, the as-prepared TiO₂ films exhibited different porous structures. XRD results showed that all TiO₂/Ag films exhibited a major anatase phase. The photodegradation of porous TiO₂ thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure.     

Influence of oxygen flow rate on photocatalytic TiO2 films deposited by rf magnetron sputtering

Titanium dioxide (TiO₂) thin films having anatase (1 0 1) crystal structure were prepared on non-alkali glass substrates by rf (13.56 MHz) magnetron sputtering using a TiO₂ ceramic target under various oxygen partial pressures. At a fixed substrate temperature of 400 °C and total gas pressure of 1 Pa after 3 h deposition. Effects of oxygen partial pressure on the structural, surface morphology, and photocatalytic activities of the TiO₂ thin films were investigated. We performed both photoinduced decomposition of methylene blue (MB) and photoinduced hydrophilicity under UV light illumination. The XRD patterns exhibited a broad-hump shape indicating the amorphous structure of TiO₂ thin films. The results showed that when the [O₂/(Ar + O₂)] flow rate increased to 50%, the photoinduced decomposition of MB and photoinduced hydrophilicity were enhanced. The water contact angle after 9 min UV illumination was approximately 4.5°, and the methylene blue (MB) solution decomposition from 12 down to 3.34 μ mol/L for 240 min UV irradiation.     

Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

In the present study, nanocrystalline TiO₂/Ag composite thin films were prepared by a sol–gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO₂/Ag films were obtained after calcining at a temperature of 500 °C. The as-prepared TiO₂ and TiO₂/Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation.After 500 °C calcination, the microstructure of PS-TiO₂ film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO₂ can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO₂ doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h.     

用于紫外光电导探测器的TiO2薄膜研究

采用直流反应磁控溅射的方法,制备了TiO2薄膜。用X射线衍射,原子力显微镜(AFM)和紫外-可见光分光光度计分别测试了TiO2薄膜的晶体结构、表面形貌及其紫外-可见光吸收谱,采用C／TiO2／ITO三层结构制备了TiO2光电导型紫外探测器,研究了它的光响应。初步实验结果表明：TiO2薄膜在4W的紫光灯辐射下,光电流可达2．1mA,10min的辐射时间内,光电流基本保持稳定,可见TiO2薄膜对紫外光有较高的灵敏度和稳定性,可作为一种良好的紫外光探测材料。     

A new route to size and population control of silver clusters on colloidal TiO₂ nanocrystals

Formation of hybrid Ag-TiO(2) nanocrystals (NCs) in which Ag clusters are uniformly deposited on individual TiO(2) NC surface has been achieved by using hydrophobic surfactant-capped TiO(2) NCs in combination with a photodeposition technique. The population of Ag clusters on the individual TiO(2) NC surface can be controlled by the degree of hydrophobicity (e.g., the number of vacant sites) on the TiO(2) NC surface while their size may be altered simply by varying irradiation time. A reversible change in color of the resulting hybrid Ag-TiO(2) NCs is induced by alternating UV light and visible-light illumination; however, the size and population of Ag clusters on TiO(2) NCs are almost unchanged. Furthermore, these materials also exhibit much higher photocatalytic performance as compared to that of Ag supported on commercial TiO(2)-P25.     

Photocatalytic degradation of methylene blue by Au-deposited TiO<Subscript>2</Subscript> film under UV irradiation

A TiO₂ photocatalytic film was prepared by the sol–gel and dip-coating methods. Au-loaded TiO₂ photocatalytic films were produced by the photodeposition method. The photocatalytic activity of the films under UV irradiation was evaluated by measuring the degradation of absorbance for a methylene blue (MB) aqueous solution. Au particles deposited on the TiO₂ film improved the photocatalytic activity under the O₂ bubbling condition. On the other hand, under N₂ or Ar bubbling, the doubly reduced form of MB, leuco-methylene blue (LMB), was formed at the beginning of UV irradiation, and then both MB and LMB were decomposed gradually by the photocatalytic reaction. In this process, Au particles on the TiO₂ film behave as electron traps.