Carbon-doped anatase TiO2 nanotube array/glass and its enhanced photocatalytic activity under solar light

To enhance the photocatalytic activity under solar light, highly ordered TiO₂ nanotube arrays (TNAs) film with anatase phase was fabricated on glass and successfully doped with carbon at various temperatures of 450–550 °C. The characterization results indicate that, after carbon doping, the TNAs still remained nanotubular structure with anatase phase. But their optical response shifted from UV to the visible light region and the recombination of photogenerated carriers was suppressed effectively. It is more important that the carbon-doped TNAs/glass (C-TNAs) samples exhibited high solar light photocatalytic activity, and 68%, 61% and 56% MO was photodegraded in 150 min by the C-TNAs calcined at 550, 500 and 450 °C, respectively. Especially, the apparent reaction rate constant of C-TNAs calcined at 550 (k, 0.065 min⁻¹) with the highest activity is 3.6 times that of pristine anatase TNAs (k, 0.018 min⁻¹). It is clear that carbon doping enhanced the photocatalytic activity under sunlight at optimized annealing temperature. The efficient activity could be attributed to the synergetic effects of strong visible light absorption, good crystallization, large surface, and enhanced separation of photoinduced carriers.     

Role of complex defects in photocatalytic activities of nitrogen-doped anatase TiO(2)

Deep impurity states associated with a substitutional nitrogen at an oxygen site (N(O)) are believed to be the source of the visible-light absorption of nitrogen-doped titanium dioxide (TiO(2)). Our comprehensive study using density functional theory (DFT) plus onsite Coulomb interaction (U) reveals that a titanium atom at an interstitial site (Ti(i)) is highly mobile and strongly binds with N(O). Hybridizations of N p with Ti d states of Ti(i) give rise to a new band at the valence band edge, eliminating the hole-trapping centers originated from the deep N(O) states. The suggested mechanism explains the photocatalytic oxidation reactions as well as the visible-light absorption observed on N-doped anatase TiO(2).     

Preparation of self-supporting hierarchical nanostructured anatase/rutile composite TiO(2) film

Via the combination of an electrospinning method with a hydrothermal reaction, a large-scale cedar-like hierarchical nanostructured TiO(2) film with an anatase/rutile composite phase was fabricated.     

New insights into the origin of visible light photocatalytic activity of nitrogen-doped and oxygen-deficient anatase TiO2

The spin-polarized plane-wave pseudopotential method, based on density-functional theory, has been used to calculate the electronic band structures and the optical absorption spectra of nitrogen-doped and oxygen-deficient anatase TiO2. The calculated results are in good agreement with our experimental measurements. These ab initio calculations reveal that the optical absorption of nitrogen-doped TiO2 in the visible light region is primarily located between 400 and 500 nm, while that of oxygen-deficient TiO2 is mainly above 500 nm. These results have important implications for the understanding and further development of photocatalytic materials that are active under visible light.     

双醇诱导自组装制备多级蛋壳结构TiO2材料及其光催化性能研究

采用双醇诱导自组装的方法可控合成了纳米片、实心球、核壳球、蛋壳球和空心球Ti02．利用SEM、TEM、XRD、UV-Vis等表征手段,探索了一元醇羟基的活泼性及丙三醇的三羟基结构在形成多级结构TiO2中的作用．丙三醇和一元醇的比例及醇热时间可控制TiO2的自组装过程而影响材料的形貌结构．同时光催化降解苯酚实验表明,具有多级结构的蛋壳球TiO2显示高活性,归因于光吸收增强．     

Synthesis of 3D hierarchical porous TiO2/InVO4 nanocomposites with enhanced visible-light photocatalytic properties

Three-dimensional (3D) hierarchical porous TiO₂/InVO₄ nanocomposites were fabricated by loading TiO₂ nanoparticles on the surface of porous InVO₄ microspheres. X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence spectroscopy (PL) were adopted to analyze the structure–property relationship of samples. The results show that the surface of as-prepared TiO₂/InVO₄ nanocomposites are composed of uniformly interconnected bi-phase nanocrystals, forming a close interface between these two components, which is favorable for the highly efficient interparticle electron transfer to achieve enhanced photocatalytic properties. However, the adsorption ability is decreased due to the loading of TiO₂ nanoparticles on the surface of InVO₄. Therefore, under the joint action of these factors, the TiO₂/InVO₄ nanocomposites achieve the best photocatalytic activity when the mole ratio of In:Ti reaches 4:1, and the visible-light photocatalytic activity is about as 3.3 times high as that of pure InVO₄ without modification.     

One-pot hydrothermal synthesis of porous anatase TiO2 nanotube formed bundles for lithium ion battery anodes

Anatase phase of TiO₂ nanomaterial has been deemed a potential anode material for lithium ion battery (LIB) applications because of its remarkable electrochemical properties. However, TiO₂ anodes always suffer from intrinsic poor electrical conductivity and slow ion kinetics, which would restrict their practical usage. To address this issue, efficient control and design of the anatase crystal structure of TiO₂ material with desirable morphology is one of the critical approaches. In this work, a good lithium storage capability of 181 mA hr g⁻¹ at rate of 0.2C, high rate performance of 70 mA hr g⁻¹ at 20C, and excellent cyclability of 117 mA hr g⁻¹ with a capacity retention of 93% at 1C after 100 cycles and 84 mA hr g⁻¹ at 10C after 1,000 cycles are observed in an optimized porous anatase TiO₂ one-dimensional nanotube bundle nanomaterial fabricated through a simple hydrothermal process with post calcination treatment. These excellent electrochemical properties of the product can be ascribed to its anatase crystal phase, 1D nanostructure, and porous framework with a large surface area, which provide it with an efficient electrode/electrolyte contact area and a faster ion/electron diffusion pathway.     

分级微纳结构TiO2空心球的制备及其在DSSC中的应用

以钛酸四丁酯为钛源,无水乙醇为溶剂,通过碳球模板法制备出直径为200nm、壳厚20～25nm的TiO2空心球（HS）.通过X射线衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）和N2吸附脱附等对产物的形貌、晶相组成、孔结构和紫外-可见光谱性质进行了表征,结果显示所制备的锐钛矿相TiO2空心微球是由初级结构纳米级TiO2晶粒构成的.将这种TiO2空心球应用于染料敏化太阳电池（DSSC）领域可以提高光阳极对光的散射.通过制备P25/HS-TiO2双层膜电极,相比单纯的P25纳米晶电极（Jsc=13.5mAcm？2,Voc=0.653V,FF=0.53,η=4.95%）可以得到更高的光电转化效率（Jsc=15.79mAcm？2,Voc=0.653V,FF=0.55,η=6.66%）.     

在光催化还原CO2中具有高催化效率的八面体Cu2O修饰的TiO2纳米管

光催化还原CO2生成烃类燃料是一种可同时解决全球变暖和能源危机问题的最有效途径之一。尽管这方面的研究已经取得了一定的进展,但是整体的光催化转换效率还非常低。因此,需要发展更加高效的催化剂。由于半导体材料禁带宽度与太阳光谱相匹配,人们已经对其进行了广泛研究。其中TiO2因具有无毒、强氧化性以及良好的光学和电学性质等而成为最主要的研究对象。但是对于光催化还原CO2反应来说, TiO2仍存在很多不足,如只能吸收太阳光谱中的紫外光,光生载流子会快速结合,以及光生空穴的强氧化能力等,这些都限制了其光催化还原CO2的效率。采用窄禁带宽度半导体修饰TiO2是解决上述不足的有效途径之一。本文采用简单的电化学方法成功制备了一种由窄禁带半导体Cu2O修饰的TiO2纳米管(TNTs)的复合物,并运用扫描电子显微镜(SEM)、X射线衍射(XRD)以及X射线光电子能谱(XPS)表征了所制备复合物的形貌、化学组成和结晶度。表征结果显示,所制备的TiO2为整齐排列的纳米管阵列结构;复合物中的纳米颗粒为Cu2O;当电化学沉积Cu2O的时间为5 min时,得到的Cu2O纳米颗粒初步呈类八面体结构。随着沉积时间的增加, Cu2O颗粒尺寸增加,具有八面体结构。 XRD和XPS结果表明, TiO2纳米管为锐钛矿,八面体Cu2O纳米颗粒的主要暴露晶面为(111)面。我们还进一步研究了不同量Cu2O纳米颗粒修饰的TiO2纳米管复合物在可见光以及模拟太阳光下光催化还原CO2的能力。在可见光下,由于自身的禁带宽度,纯净的TiO2纳米管没有任何光催化还原CO2的能力;经过Cu2O纳米颗粒的修饰,复合物显现出明显的光催化还原CO2的能力,其中经过30 min Cu2O沉积的TNTs具有最高的光催化效率。在模拟太阳光下,经过15 min Cu2O沉积的TNTs具有最高的光催化效率。在所有光催化还原CO2过程中,主要碳氢产物为甲烷。为了深入地理解该复合体系在还原CO2中的高催化效率,我们对催化剂进行了进一步的表征。紫外-可见漫反射光谱表明, Cu2O八面体纳米颗粒的沉积将TNTs的吸收光谱拓展到了可见光区域,提高了复合物对太阳光的吸收能力。此外,我们还通过测试所制样品的光电流反应、荧光发射光谱以及电化学阻抗谱,研究了催化剂中光生电子和空穴的分离和迁移能力。结果表明,适量的Cu2O沉积提高了复合物对光的吸收能力,增加了光生载流子的数量,从而使更多的光生载流子参与光催化反应。综上,本文首次报道了八面体Cu2O纳米颗粒修饰TNTs复合物的光催化还原CO2的能力。在一定量的Cu2O纳米颗粒修饰下,该复合物在光催化还原CO2生成烃类反应中表现出高效性。经过一系列详细的表征和讨论,我们认为其高效性主要源于三个方面：(1) TNTs的管状结构为反应物的吸附提供了大量的活性位点,同时一维的管状结构更有利于光生载流子的运载,从而提高了电子和空穴的分离;(2) Cu2O纳米颗粒的修饰提高了催化剂对光的吸收,促进催化剂最大程度地利用太阳光;(3) TiO2和Cu2O之间导带以及价带位置的匹配,在减少光生载流子复合的同时也降低了TiO2价带上空穴的氧化能力,从而抑制了CO2还原产物的再氧化过程。     

孔道三维相互连通锐钛矿TiO2-SiO2纳米复合介孔材料的制备及其高光催化活性

本文报道一种孔道三维相互连通锐钛矿TiO2-SiO2纳米复合介孔材料的制备.该介孔材料是以两维六方有序结构、直孔道、锐钛矿70TiO2-30SiO2-950纳米复合介孔材料(于950oC晶化2 h)为前驱体, NaOH为SiO2的刻蚀剂,通过“在孔壁内造孔”的方法获得.我们的策略是采用温和的造孔条件,如稀NaOH溶液,合适的温度与固/液比等.采用X射线衍射(XRD),透射电镜(TEM)和低温N2吸附等技术对样品的介孔结构进行了系统表征.结果表明,墙内孔的密度非常高,孔径均一(平均尺寸3.6 nm),且在三维网络高度连通原孔道,但介孔结构仍保持其完整性.锐钛矿纳米晶粒的结晶度和大小在墙内造孔前后基本保持不变.该材料光催化降解罗丹明B(0.303 min–1)与亚甲基蓝(0.757 min–1)的活性相当高,此活性分别是其母体材料的5.1和5.3倍,甚至是Degussa P25光催化剂的16.5和24.1倍.这充分表明三维连通孔道结构对活性的大幅提高起了关键作用.孔道三维连通式锐钛矿TiO2-SiO2纳米复合介孔材料对上述污染物展现出意想不到的高降解活性,显著高于迄今已报道的金属氧化物基介孔材料对上述污染物的降解活性.更重要的是,该光催化剂具有相当高的稳定性和重复使用性.相信,本方法将为具有超高性能的孔道三维相互连通其它金属氧化物基介孔材料的制备铺平了道路.
　　小角XRD结果表明,母体材料的孔道是两维六方有序结构,在孔壁内造孔之后,样品原有的介孔结构仍保持其规整性.宽角XRD结果显示,二氧化钛的晶相是锐钛矿,晶粒尺寸为10.8 nm.造新孔之后,锐钛矿纳米晶粒的结晶度和大小与母体样品的相比变化不大. TEM结果显示,母体样品的孔壁内没有孔.孔道是两维六方有序排列的直孔道,孔径大小均一(平均尺寸4.1 nm).高分辨透射电镜(TEM)观察揭示,锐钛矿纳米晶粒(平均大小11.3 nm)在孔壁内随机排列,并与无定形SiO2纳米颗粒相互连接,相间共存,形成类似“砖块?水泥砂浆”砌成的孔壁,这种独特的复合骨架结构赋予其很高的稳定性.当一些SiO2纳米颗粒被去除之后, TEM观察显示,孔壁内有密集分布的孔,这些孔取向随机,并在三维方向连通原孔道,但介孔骨架结构仍保持其完整性.墙内孔的大小范围很窄(3.1?4.3 nm),平均大小为3.6 nm.高分辨TEM观察显示,锐钛矿晶粒大小与母体材料内的相比基本未变.上述结果与XRD结果一致.低温N2吸附表征结果显示,母体样品内只有一种孔道,孔径为4.0 nm.去除部分SiO2后的样品内有两种孔道,孔径分别是3.4和4.1 nm.这些结果与TEM的观察吻合.罗丹明B与亚甲基蓝在造孔前后样品内扩散速率评价结果显示,其在三维连通孔道内的扩散速率很高,大约是其母体材料内的5倍以上.这表明相互连通的孔道网络结构非常有利于客体分子在其内扩散.光催化降解性能评价结果显示,罗丹明B与亚甲基蓝在相互连通孔道内降解的速率相当高,分别是其在不连通孔道内的5.1和5.3倍.这充分证明孔道三维相互连通对活性的大幅提高起了关键作用.我们对材料的稳定性和重复使用性作了评价,经过10次循环使用孔道三维相互连通锐钛矿TiO2-SiO2纳米复合介孔材料,其吸附与光催化降解罗丹明B的性能变化不大.这充分证明本文制备的孔道连通复合介孔材料的性能是相当稳定的和可重复使用的.该方法可用于制备具有超高性能的孔道三维相互连通其它金属氧化物基介孔材料,如Nb2O5, Ta2O5等.     

Pd/N共掺杂TiO2的制备及其光催化活性

将纳米管TiO2浸入含尿素和硝酸钯的乙醇溶液中,将乙醇超声挥发后所得样品先在空气中600℃下煅烧,再在H2气氛中400℃中热还原,得到Pd/N共掺杂TiO2.分别采用DRS、X射线衍射仪及X射线光电子能谱仪分析了掺杂TiO2样品的光吸收能力、晶体结构及表面化学组成;并评价了其对紫外光和可见光照下丙烯降解反应的催化活性.结果表明,共掺杂TiO2样品的活性优于单一Pd或N掺杂TiO2.其原因在于,Pd和N共掺杂具有协同作用,从而共同提高了TiO2的光催化活性.     

钒掺杂TiO2/AC负载催化剂的制备及光催化活性

以TiO2为主要成分的光催化剂的研究已日益受到人们的广泛关注[1-6]。但TiO2粉末的回收和流失问题难以解决,固定化TiO2负载催化剂的研制是解决这一问题的有效手段[2-6]。从实际应用的观点看,TiO2的光催化剂活性还有待进一步提高。研究发现,大多数过渡金属离子和少数非金属离子的     

Synthesis of anatase TiO2 in a vinyl-containing ionic liquid and its enhanced photocatalytic activity

TiO₂ microspheres were synthesized by the sol–gel method using the ionic liquid (IL) 1-vinyl-3-propylimidazolium iodide (VPIM⁺I^?) as a reaction medium, then calcined at 500 °C. The samples were characterized by X-ray diffraction, scanning electron microscopy, and ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy. The phase of TiO₂ microspheres is anatase, and VPIM⁺I^? is able to favor the growth of anatase phase and prevents the collapse of small pores. The photocatalytic activity of TiO₂-IL was tested by degradation of 2-nitrophenol under UV light illumination. The photocatalytic activity of TiO₂-IL was higher than that of samples prepared in the reaction medium without VPIM⁺I^?.     

超临界流体干燥法制备TiO2／C纳米粒子及光催化性能

以TiCl4为原料,采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO2/C复合光催化剂.以苯酚的光催化降解对所得催化剂的催化活性进行了评价.结果表明,纳米TiO2/C复合粒子与单组分TiO2比较,复合粒子光催化活性高于单组分的TiO2,h苯酚降解率高达975 ％,COD为957%.并用XRD、TEM、 UV-Vis和XPS等手段进行了表征,iO2以锐钛矿型形式存在.比较了不同制备方法制得的TiO2/C复合催化剂,得出超临界干燥法制备的光催化剂具有粒径小,比表面积大,分散性好,光催化活性高等特点.     

阳极氧化TiO2纳米管阵列的制备与掺杂*

近年来,TiO₂纳米管阵列的制备与应用得到了广泛的研究。阳极氧化法制备TiO₂纳米管阵列具有工艺简单、成本低廉、易于放大等优点,引起了极大关注。本文综述了阳极氧化法制备TiO₂纳米管阵列的研究现状,基于TiO₂纳米管阵列在阳极氧化过程中的生长机理,讨论了决定阳极氧化TiO₂纳米管阵列形成的主要因素。结合本组的研究工作,总结了如何通过改变电压、升压速率、电解液、温度和氧化时间,实现纳米管管径、管壁厚度、管长的有效控制,提高TiO₂纳米管阵列的表面形貌质量。最后介绍了TiO₂纳米管阵列掺杂改性方面的研究进展。     

Amorphous carbon-linked TiO_2/carbon nanotube film composite with enhanced photocatalytic performance:The effect of interface contact and hydrophilicity

Carbon nanotube film(CNTF) can be used for photocatalysis and water treatment due to its porous structure,good stability and excellent electrical properties.In this work,TiO_2/amorphous carbon/carbon nanotube film(TCC) composite with uniform structure was prepared by a simple atomization spraying method.Rhodamine B(RhB) was used to test the photocatalytic activity of TCC.TCC composite exhibits good photocatalytic activity under ultraviolet light.In particular,the degradation efficiency of rhodamine B(RhB) by TCC sprayed with 9 layers of TiO_2(9 TCC) increased by 1.45 times than of TiO_2 under ultraviolet light.The enhanced photocatalytic activity of TCC is attributed to the CNTF,which can broaden the light response range of TCC and improve the migration efficiency of electrons.The existence of amorphous carbon will promote these advances.Moreover,the better hydrophilic properties would enhance the catalytic performance happened on the solid-liquid interface.Finally,the photocatalytic mechanism and degradation intermediates of the TCC composite were proposed.     

C/Nd/TiO2催化剂的制备及光催化性能研究

利用溶胶-凝胶法以钛酸四丁酯为钛源、硝酸钕为钕源、葡萄糖为碳源,制备了C和Nd单掺杂及共掺杂TiO_2催化剂。通过XRD、XPS、漫反射、SEM和物理吸附对所制备的催化剂进行表征与评价。结果表明,C和Nd共掺杂TiO_2的晶型仍为锐钛矿型,表面光滑,晶粒大小分散均匀,孔径分布在20~34 nm之间;与其他三种催化剂相比,共掺杂催化剂比表面积较大;通过掺杂C和Nd元素,形成新能带E_(C2p)和E_(Nd3+4f),降低了电子跃迁能,有利于光催化活性增强。C和Nd共掺杂TiO_2对可见光的吸收能力有明显提高,对甲基橙染料降解效果较佳,其脱色率为61.24%。