Photocatalytic oxidation activity of titanium dioxide film enhanced by Mn non-uniform doping

1 Introduction Heterogeneous photocatalysis is an effective technique for reducing the concentration of pollutants at low concentration. It has been demonstrated that almost all organics can be oxidized to generate carbon dioxide, water and simple mineral…     

Preparation and photocatalytic activity of PANI/TiO2 composite film

1. Introduction As an advanced oxidation technique (AOT), photocatalytic oxidation of semiconductor nanopar-ticles has been widely investigated by several groups during the past two decades [1-2]. Among all types of oxide semiconductor photocatalysts, nano-TiO2 is a very important photocatalyst for its strong oxidiz-ing power, nontoxicity, and long-term photostability [3]. Some researchers have reviewed the photocata-lytic mechanism of nano-TiO2 [4-5]. Generally, when the surface of TiO2 i…     

Ce-TiO2/硅藻土的制备、表征及其光催化活性

以硅藻土（KL）为载体,用溶胶-凝胶法将铈掺杂二氧化钛包覆在硅藻土上（Ce-TiO2/KL）。采用XRD、DRS、SEM对其进行表征,以250 W高压汞灯作光源,甲醛作为反应底物表征其光催化活性。结果表明：Ce-TiO2包覆在硅藻土颗粒上,并能在较高的煅烧温度（500℃）范围内保持锐钛矿晶体结构;随着铈掺杂含量的提高,J2Ce-TiO2/KL对可见光的吸收明显增强,有利于充分利用太阳光。由此可见,TiO2固定在硅藻土上时,铈掺杂不仅提高了其活性,还导致其激发波长红移,还有利于回收利用。     

Zn与Ti摩尔比对磁控溅射TiO2-ZnO异质复合薄膜微观结构及光催化性能的影响

利用磁控溅射离子镀技术制备系列TiO 2-ZnO异质复合薄膜,通过调节溅射靶材电流的大小控制薄膜中n（Zn）/n（Ti）值。采用AFM﹑SEM﹑Raman和XPS手段表征薄膜的微观形貌和结构,并以甲基橙作为光催化污染物,研究n（Zn）/n（Ti）对TiO 2-ZnO复合薄膜微观结构及光催化性能的影响。结果表明：随着n（Zn）/n（Ti）的增大,复合薄膜的晶粒尺寸先减小而后增大,其粗糙度也先增大而后减小,且均在n（Zn）/n（Ti）为1/9.3时达到极值;n（Zn）/n（Ti）对薄膜中元素Ti和Zn的价态无明显影响,均以TiO 2和ZnO形式存在,但比值的大小影响薄膜退火后TiO 2中锐钛矿/金红石异质结的数量;n（Zn）/n（Ti）越大,复合薄膜的光响应范围及吸光度越大,其响应光谱最大可扩展150 nm,波长可至450 nm,但异质复合薄膜光催化效果与其并不对应,取决于ZnO对TiO 2复合薄膜微观结构的影响,当n（Zn）/n（Ti）为1/9.3时,薄膜的降解速率最大,光催化能力最好。     

Enhancement of photocatalytic activity of TiO2 film electrode by in situ photoelectro-generating active chlorine

The photoelectrocatalytic activity of TiO2 film electrodes in the degradation of nitrite ion was greatly enhanced in the presence of chlorine ion. The influences of NaCI concentration and initial pH value on the degradation rate of NO2^- and active chlorine production were studied. The results show that the decay rate of NO2^- and the accumulation rate of active chlorine increase with increasing NaCl concentration. At pH〈8, both the decay of increasing NaCl concentration, while at pH〉 10, they are suppressed NO2^- and active chlorine formation rates are enhanced with In addition, contrast to conventionally accepted view, in which an advantage of anatase over the rutile modification of TiO2 is in terms of photoactivity, it is found that a thermal oxidation futile TiO2 electrode is more suitable for both photogenerating active chlorine and degradingNO2^- in the presence of Cl^-. The correlative mechanism was also discussed in detail. Specific adsorption of Cl^- on the electrode causes its energy band edges to move towards positive value and also lower the photocurrent, thus less OH· radicals are produced. However, more active species of Cl that have longer lifetime are available to take part in the oxidation of NO2^- thus improving its degradation rate.     

单分散纳米TiO2光催化剂的水解-溶胶制备法

以Ti(SO4)2为原料，在一定温度下直接水解、胶溶、加入晶种、熟化，制备出单分散性、热稳定性良好、平均粒径在22nm左右、比表面积在80m^2／g以上的TiO2纳米微粒。研究了Ti(SO4)2浓度、水解时间及晶种对纳米微粒粒径的影响。对样品进行了TG-DTA，XRD和SEM分析。结果表明：样品经真空冷冻干燥后，TiO2粉体主要为锐钛矿型，且随焙烧时间增加和温度升高，其金红石型含量显著增多，粉体粒径也有一定增大，但在不同的温度区间粒径增长速率有较大的区别。     

Synthesis of iron(Ⅲ)-doped nanostructure TiO2/SiO2 and their photocatalytic activity

Iron(Ⅲ)-doped nanostructure TiO2-coated SiO2 (TiO2/SiO2) particles were prepared using the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized employing the sol-gel method with TiCl4 as a precursor. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), SEM, EDS, XPS, and XRD. The experimental results show that TiO2 nanopowders on the surface of SiO2 particles are well distributed, the amount of TiO2 is increased with the adding of coating layers, the pure anatase-TiO2 coating layers are synthesized at 500℃, and the photocatalytic activity of Fe3+-doped TiO/SiO2 is higher than tnat of undoped TiO2/SiO2.     

Deposition of photocatalytic TiO2 and N-doped TiO2 films by arc ion plating

TiO2 and N-doped TiO2 films were deposited on the glass substrates by arc ion plating method. The results show that the deposition rate does not change with the increasing deposition time. The increase of mass flow rate of N2 gives rise to the increase of deposition rate. All as-deposited TiO2 and N-doped TiO2 films are amorphous. The anatase TiO2 phase with preferred orientation （101） is acquired by post-annealing at 400 ℃ for 2 h. The incorporation of N into the TiO2 films and the heat treatment extensively shift the band edge to the visible light region.     

N掺杂TiO2薄膜光催化性能的研究

采用溶胶-凝胶法，以Ti（OC4H9）4和氨水等为原料制备纯二氧化钛、N掺杂以及N，Zn^2＋共掺杂的二氧化钛光催化薄膜。用X射线衍射和X光电子能谱等对薄膜进行了表征，紫外光和可见光下催化剂降解甲基橙溶液的实验结果表明，掺杂TiO2薄膜比无掺杂TiO2薄膜的光催化效率明显提高，并且可见光下对甲基橙溶液有一定的光催化活性，但Zn^2＋的存在对掺杂薄膜的光催化效率没有显著改善。分析原因可能是N掺杂在价带和导带之间形成了缺陷能级，减小了TiO2的禁带能隙，从而使TiO2的吸收带发生红移，实现可见光响应。     

TiO2纳米管阵列的制备与改性研究进展

TiO_2纳米管阵列具有比表面积大、吸附能力强和电子迁移率高等优点,在光催化降解有机污染物、染料敏化太阳能电池、光解水制氢、气敏元器件等领域具有广阔的应用前景,是当前人们的研究热点之一。对TiO_2纳米管阵列的常见制备方法及其制备原理进行了综述,并分析了各种制备方法的优缺点。同时,TiO_2由于是宽禁带半导体,其光吸收波长主要集中在紫外光区,光响应范围窄导致其对可见光的利用率较低。降低TiO_2的禁带宽度、抑制光生载流子-空穴的复合,成为提高TiO_2纳米管阵列的光催化效率及太阳能利用率的改性研究重点。着重阐述了国内外通过掺杂金属和非金属离子、沉积贵金属、复合半导体等方法来引入杂质或缺陷,使其光生载流子-空穴的复合减缓,或使其吸收光谱红移,从而达到提高光催化效果的相关研究进展,并指出了今后TiO_2纳米管阵列在制备、改性和应用等方面的研究重点和方向。     

Characterization and photocatalytic activity for methylene blue degradation of iron-deposited TiO2 photocatalyst

Iron-deposited TiO2 was prepared by photo-reducing ferric ions. The photocatalytic activity of methylene blue degradation was enhanced after TiO2 was deposited with iron, and the optimum n(Fe)/n(Ti) is 0. 25%. TiO2 and iron-deposited TiO2 are anatase and rutile, and anatase is the dominant crystalline phase. In all samples, theXRD patterns indicate that there are no characteristic peaks of iron to be detected. XPS confirms that Fe^3 and Fe^2 are present on the surface of 0.5% iron-deposited TiO2, however they are not susceptible to XRD detection. The thermodynamics analysis shows that the alternative possibility of reduction from the Fe^3 /Fe^2 couple seems plausible, but Fe^2 can not be reduced to Fe. The fluorescence intensity weakens after iron is deposited on TiO2, because iron deposited traps photo-generated electrons and holes. The fluorescence intensity order of TiO2 and iron-deposited TiO2, from strong to weak, is in good agreement with that of photocatalytic reactiveness TiO2 and iron-deposited TiO2, from low to high.     

Electrodeposition of photocatalytic TiO2 film on surface of alumina prepared by anodic oxidation

A new electrochemical method to prepare photocatalytic TiO2 thin film was developed, by which the TiO2 was electrodeposited on surface of alumina by AC electrolysis in solution consisting of K2 [TiO(C2O4 )2] and C2H2O4. The deposited TiO2 thin film was primarily characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy dispersive spectrum (EDS) methods. The photocatalytic properties of this film were also studied by the photocatalytic degradation of methyl orange. The results show that the TiO2 film electrodeposited by this method is mainly in amorphous and with a little crystalline component mixed anatase and rutile. The surface of the alumina prepared by anodic oxidation is porous and the TiO2 electrodeposited on it is scattered and incompact. TiO2 thin film fixed on the surface of alumina shows photocatalytic activity to the degradation of methyl orange.     

Photocatalytic activity enhancing for TiO2 photocatalyst by doping with La

La doped nanocrystalline TiO2 photocatalyst was developed by sol-gel method. The prepared La-TiO2 photocatalysts with anatase phases were characterized by X-ray diffractometry （XRD）, UV-Vis absorption spectroscopy, and photoluminescence spectra （PL）. The photocatalytic activity was evaluated by the photocatalytic degradation of phenol in solution under sunlight irradiation. The results show that the crystallinity of anatase is improved by La doping. Moreover, La not only suppresses phase transition from anatase to rutile but also exhibits an absorption in the λ≥400 nm range. The photocatalytic activity of La-doped TiO2 photocatalysts exceeds that of pure TiO2 photocatalyst prepared by the same method when the molar ratio of La to Ti is kept at 0.3%.     

Zr和N共掺杂TiO2的制备、表征及其光催化性能

利用水解沉淀法制备TiO2、N-TiO2、Zr-TiO2以及Zr和N共掺杂的纳米TiO2,用TEM、XRD、XPS和UV-Vis-DRs等方法对光催化剂的结构、元素组成和对可见光的响应等性能进行表征,并以甲基橙为目标降解物,测试其光催化降解效果。结果表明,Zr掺杂能够降低TiO2光催化剂的粒径;Zr和N共掺杂可以起到协同作用,提高样品的光催化活性,同时增强样品在可见光区的响应。Zr和N共掺杂TiO2在高压汞灯光照下比TiO2具有更好的光催化效果,2%Zr和N共掺杂TiO2光照3h后对甲基橙的降解率比纯TiO2提高32%。     

Mn添加量对Mg-2Zn合金组织及生物耐蚀性的影响

研究了Mn添加量对Mg-2Zn合金显微组织和耐腐蚀性能的影响。结果表明,3种不同Mn含量的Mg-2Zn合金显微组织差别不明显,但当Mn的加入量超过0.5%时,显微组织中析出的Mn含量增多;电化学与浸泡试验结果表明Mg-2Zn-0.2Mn与Mg-2Zn-0.5Mn合金的耐蚀性相近,但Mg-2Zn-1.0Mn合金的耐蚀性明显下降。     

热处理制度对纳米晶Mn0．6Zn0．4Fe2O4铁氧体纤维结构和磁性能的影响

以柠檬酸及金属盐为原料,采用有机凝胶先驱体转化法制备直径0.5～3.0 μm、平均晶粒尺寸为8.7～31.8 nm的Mn0.6Zn0.4Fe2O4铁氧体纤维.利用XRD、SEM和VSM分别对前驱体凝胶的结构、热处理产物的物相、形貌及磁性能进行表征.结果表明:Mn-Zn铁氧体相的稳定性主要受热处理气氛中氧含量的影响,在空气气氛中将发生部分分解,而在氮气气氛中能获得纯的尖晶石型铁氧体相;在400 ℃时获得的Mn0.6Zn0.4Fe2O4铁氧体纤维因晶粒尺寸小于临界尺寸而表现出超顺磁特性,但随热处理温度的升高和保温时间的延长,Mn0.6Zn0.4Fe2O4铁氧体纤维的饱和磁化强度、矫顽力和晶粒尺寸均逐渐提高,特别是在500 ℃以后,增长尤为显著.     

ZrO_2／TiO_2复合光催化膜的微弧氧化法制备及表征

采用微弧氧化方法和原位生成的Zr（OH）_4胶体颗粒,在纯钛基体上制备ZrO_2／TiO_2复合光催化膜。采用SEM、EDX、XRD、UV-VisDRS等分析手段,对膜层进行分析表征。结果表明：复合膜显示出层状和多孔的结构,由锐钛矿、金红石和ZrO_2组成;相对于纯TiO_2膜,复合膜层的光吸收截止边缘产生红移;ZnO_2／TiO_2复合膜层和纯TiO_2膜层在紫外光照射下,对罗丹明B的光催化速率常数分别为0．0442和0．0186h~（-1）。     

Photocatalytic degradation of phenol in aqueous solution using TiO_2/Ti thin film photocatalyst

1　INTRODUCTIONHeterogeneousphotocatalysishasbeenwidelyin vestigatedasanalternativemethodfordegradationoforganicpollutantsinrecent 2 0 years .TiO2 isthemostinvestigatedphotocatalystuptodatebecauseitisoftenusedinthetreatmentofpollutantchemicals ,basedonitsremarkableactivity ,chemicalstability ,andalsoonitsnon toxicproperties.Phenolor phenoliccompoundsexistwidelyindailylifeandinindustrialwastewateroriginatingfromcokeovens ,petroleummanufactureorpaintstrippingoperations ,andhavebecomecommonp…