H2 production of (CdS–ZnS)–TiO2 supported photocatalytic system

Mixed semiconductor (CdS–ZnS)–TiO₂(1 : 1 : 1) mixture system over different supports like MgO, CaO, γ-Al₂O₃, SiO₂ and modified MgO and CaO, have been prepared, characterized and tested for H₂ production in a S²⁻⧸SO²⁻₃ mixture solution. (CdS–ZnS)–TiO₂(D) over MgO support wherein the TiO₂ taken is from Degussa (D) sample gives 206.7 μmol⧸h of H₂ production and this catalyst sustain the H₂ production rate for longer durations. Dopants like Li₂O, Cs₂O or K₂O make MgO and CaO supports act like super basic oxide when they are doped and in turn increase the photocatalytic activity. The (CdS–ZnS)–TiO₂(I) system wherein the TiO₂ taken from Titanium Isopropoxide, supported on 20 wt% Li₂O doped CaO is found to give 209.8 μmol⧸h rate of H₂ production. Characterization studies like UV-Visible spectra, X-ray Diffraction spectra and Scanning Electron Microscope photographs were taken for all the catalysts and the data generated over these samples is evaluated. A scheme of H₂S photocatalytic decomposition of ZnCdS–TiO₂(D⧸I) over different supports in the presence of S²⁻⧸SO²⁻₃ substrate, is proposed indicating the formation of thiosulfate cycle at this heterojunction. © 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.     

纳米TiO2光催化剂改性研究进展

综述近年来关于纳米TiO2光催化剂的改性研究进展,详细叙述针对该催化剂的各种改性方法的原理,制备方法及目前的研究进展,展望该领域的研究方向.提出以共掺杂为基础的改性、可重复利用的催化剂以及纳米TiO2薄膜制备和大型反应器的设计是研究的主要课题.     

TiO2纳晶多孔薄膜固态太阳电池

该文报导了用交联聚醚聚氨酯 (PEU)凝胶网络型高分子和以聚硅氧烷为基础含有聚氧化乙烯 (PEO)内增塑链的凝胶网络高分子为电解质的TiO2 纳晶固态太阳电池的制备及性能。在所研究的 3种固体电解质 (SPE 1,SPE 2及SPE 3)中 ,具有低交联度、高盐 (KI)含量的凝胶网络型高分子电解质 (SPE 2 ) ,其离子导电性最佳 ,可以与液体电解质相比 (σ =2 1× 10 -3S·cm-1) ,由此构成的固态电池具有最好的光电化学性能。改进凝胶网络高分子电解质的结构组成以及优化TiO2 纳晶多孔薄膜 /高分子凝胶的界面可以进一步改善固态电池的性能 ,提高转换效率。     

电泳法制备纳米TiO2薄膜

通过电泳法在导电玻璃上制备了二氧化钛薄膜,利用SEM及XRD对样品形貌和结构进行了表征.比较了不同分散剂对薄膜制备的影响.将所制备的薄膜用于染料敏化太阳电池的光阳极,得到了较高的开路电压和短路电流.其中以异丙醇做溶剂并加入少量聚乙二醇所制备的二氧化钛薄膜用于染料敏化太阳电池,开路电压达到0.66V,短路电流达到8.14mA/cm2.     

掺Ag复合纳米TiO2光催化性能

通过溶胶-凝胶法和光还原法制备掺Ag复合纳米TiO2.用XRD表征了TiO2的晶体形态.以典型偶氮结构的甲基橙水溶液为模拟对象,研究掺Ag复合纳米TiO2光催化性能.实验结果表明,TiO2悬浮体系中甲基橙的光催化降解符合Langmuir动力学规律.根据动力学计算,掺Ag复合TiO2和单纯TiO2对甲基橙的降解速率常数分别为27.34mg/(L·h)和14.42mg/(L·H),光催化的活性提高了近2倍.因此有望通过这一技术制备出比单纯TiO2更好的光催化剂.     

染料敏化纳米TiO2薄膜太阳电池测试

从染料敏化纳米薄膜太阳电池(以下简称DSCs)结构和原理出发,探讨DSCs与常规硅太阳电池在测试上的区别。讨论了不同光源光谱条件、光强、数据采集速率以及环境温度对DSCs光伏性能测试的影响,获得准确测试DSCs光伏性能的方法和技术。     

TiO2/沸石光催化性能的研究

以钛酸丁酯为原料,用溶胶-凝胶法制备了TiO2并将之负载到天然沸石上。使用XRD、SEM及比表面积分析仪对样品进行了表征;以甲基橙为光催化降解模型,紫外灯为光源,用褪色率等对光催化剂性能进行了评价;对天然沸石负载TiO2的光催化性能及影响因素进行了探讨。实验表明:300℃焙烧后、含有少量金红石相混晶的锐钛矿TiO2光催化能力最好。甲基橙的初始浓度及光强越大,光解率也越大,在pH约等于6时,光解率达到最大。     

Ho掺杂纳米TiO2光催化性能研究

以钛酸四正丁酯为原料,采用溶胶-凝胶法制备了纯的和Ho掺杂的TiO_2纳米粒子,对样品进行了TG- DTA、XRD和UV-Vis吸收光谱分析,并以甲基橙的光脱色反应考察了样品的光催化性能。发现Ho的掺杂抑制了TiO_2粒径的长大,细化了晶粒;Ho掺入到TiO_2的晶格中,引起了晶格的畸变和膨胀;Ho的掺杂使TiO_2的吸收带边发生微小的蓝移,且在450nm和540nm光区附近产生吸收;适量Ho的掺杂可提高TiO_2的光催化性能,紫外光照下,Ho的掺杂量为0.3%时,光催化性能最佳;可见光下(波长>420nm),Ho掺杂的TiO_2呈现光催化活性,210min内甲基橙的脱色率可达21.6%。     

活性炭与TiO2相结合去除室内污染物甲醛的实验研究(Ⅱ)

将TiO2分别与两类活性炭吸附材料相结合,分析不同活性炭吸附作用对污染物甲醛的光催化去除影响.实验结果表明,以活性炭颗粒为载体负载TiO2催化剂形成的催化剂膜对污染物的去除效率低于以蜂窝活性炭网为载体负载催化剂形成的催化剂膜;同以玻璃为载体的催化剂膜相比,以活性炭材料为载体的催化剂膜对污染物的去除同样表现为传质控制过程和光催化控制过程,且随流速增加,光催化反应从传质控制向光催化控制过渡的转换点提前,在低污染物浓度条件下,污染物的光催化去除受污染物传质和驻留时间控制,且驻留时间的影响是主要的,随着驻留时间的增加,污染物的去除率提高.     

TiO2–Au plasmonic nanocomposite for enhanced dye-sensitized solar cell (DSSC) performance

Anatase TiO₂ nanoparticles dressed with gold nanoparticles were synthesized by hydrothermal process by using mixed precursor and controlled conditions. Diffused Reflectance Spectra (DRS) reveal that in addition to the expected TiO₂ interband absorption below 360 nm gold surface plasmon feature occurs near 564 nm. It is shown that the dye sensitized solar cells made using TiO₂–Au plasmonic nanocomposite yield superior performance with conversion efficiency (CE) of ～6% (no light harvesting), current density (J_SC) of ～13.2 mA/cm², open circuit voltage (V_oc) of ～0.74 V and fill factor (FF) 0.61; considerably better than that with only TiO₂ nanoparticles (CE ～ 5%, J_SC ～ 12.6 mA/cm², V_oc ～ 0.70 V, FF ～ 0.56).     

活性炭与TiO2相结合去除室内污染物甲醛的实验研究(Ⅰ)

将光催化技术与活性炭吸附技术相结合,利用活性炭吸附功能,强化污染物向催化剂表面的传质,在催化剂表面形成局部高浓度,提高室内低污染物浓度条件下的光催化去除效率.实验结果表明,活性炭吸附材料存在吸附饱和,而将活性炭材料与光催化剂相结合,一方面可以提高污染物光催化去除效率,另一方面,污染物的光催化作用可以延缓活性炭材料的吸附饱和,延长活性炭材料的使用寿命;同时在活性炭材料上负载催化剂则存在着最佳的催化剂负载量.这两种捌术相结合形成的催化剂膜,既具有一定的牢固性又有一定活性.本研究结果为光催化技术的应用提供了理论支持.     

Platinum-catalyzed Nb–doped TiO2 and Nb-doped TiO2 nanotubes for hydrogen generation in proton exchange membrane water electrolyzers

This paper studies the catalytic activity of Pt deposited onto Nb-doped titania supports toward the hydrogen evolution reaction (HER). New catalysts based on Nb-doped TiO₂ nanoparticles (nNb-TiO₂) and Nb-doped TiO₂ nanotubes (nNb-TNTs), with n in the range 3–10 at % (Nb + Ti), were synthesized. The specific surface areas of nNb-TNTs were 250–300 m²g^-1, about three times higher than those of nNb-TiO₂. X-ray diffraction showed the Nb incorporation into the TiO₂ lattice with its consequent lattice expansion. The X-ray photoelectron spectra of Pt deposited onto Nb-doped titania revealed a negative charge accumulation on Pt, thus denoting strong metal-support interaction. The electrochemical characterization in acidic media showed that Pt supported on nNb-TiO₂ and nNb-TNTs presented better activity toward the HER than that of Pt deposited onto the un-doped supports and commercial Pt on carbon. The best performance was obtained with a small Nb doping of 3 at %.     

Enhancement of hydrogen energy from Casuarina equisetifolia using NiO–Pr2O3/TiO2 and NiO/TiO2 nano composites

Hydrogen is the eco friendly fuel that can supplement the requirements for power generation.Nickel based nano composites attracted much researchers due to its wide applications in various fields viz., solar cells, capacitors, batteries and aerospace engineering. NiO-Pr₂O₃/TiO₂ and NiO/TiO₂ nano composites have high catalytic activity for producer gas conversion by the process of decomposition of tar molecules generated during biomass gasification. In this work, we have investigated the growth of NiO-Pr₂O₃/TiO₂ and NiO/TiO₂ nano composites by the method of deposition precipitation technique. Structural investigation represented that the TiO₂ possess cubic structure with preferential orientation along (111) plane. Morphological features denoted the formation of non agglomerated grains. The sizes of the grains with nanometer scale have been identified by transmission electron microscopy. The surface area and porosity nature of the nano composites has been analyzed using Branauer Elmer Teller and Barrett-Joyner - Halenda techniques, respectively. The estimated value of surface area is found to be 110 and 81 m²g^-1 for NiO-Pr₂O₃/TiO₂ and NiO/TiO₂ nano composites, respectively. The increment in the content of hydrogen present in the producer gas has been investigated using catalytic tar cracking method. The NiO-Pr₂O₃/TiO₂ nano composite exhibited better tar cracking with higher content of hydrogen conversion than NiO/TiO₂.     

磁控溅射法制备TiO2薄膜的光催化特性

采用中频磁控溅射法与弧抑制技术相结合制备出了廉价、大面积、光催化效果好并且膜与衬底结合牢固的TiO2薄膜。通过改变衬底材料、薄膜厚度、掺杂类型等参数,发现在不锈钢丝网衬底上制备的氮掺杂薄膜在500nm厚时具有最好的光催化效果。用此方法制备TiO2薄膜可以大面积连续生产,具有廉价、催化性能好,与衬底结合牢固、方便应用等优点,因而可以广泛的应用于空气净化器中,从而有利于TiO2光催化薄膜的产业化发展。     

TiO2-xNx光催化剂的制备及其活性研究

在sol-gel法制备TiO2的过程中引入氨水进行水解,制备了具有可见光活性的TiO2-xNx催化剂,采用UV-Vis、BET、XPS等手段进行表征,以苯甲酸为模型污染物,氙灯为模拟太阳光源,评估了催化可见光催化活性.结果表明,随着焙烧温度的升高,TiO2-xNx的吸光特性增加,当温度超过350%后TiO2-xNx中的氮会在高温下被氧化掉,其吸光特性又降低;此时TiO2-xNx的吸收阈值为422nm,对应的禁带宽度为2.9eV;孔径分布在2.5～8.2nm之间,BET比表面积为139.3m2/g;经计算其x=0.0282,即TiO2-xNx可表示为Ti1.9718N0.0282;在入射波长分别为500nm和600nm时,TiO2-xNx对苯甲酸的去除率分别为6.5%和4.6%,相应的矿化率为3.2%和2.5%.     

TiO2-B-S光催化剂的制备及性能研究

利用水热法直接制备了B、S共掺杂改性的光催化剂TiO_2-B-S。XRD表明该光催化剂为锐钛矿晶型,硫硼掺杂能抑制TiO_2粒径的生长;UV-vis表明该催化剂对可见光吸收增强,吸收带边明显红移。XPS显示B、S共掺杂改性使得TiO_2-B-S表面羟基氧含量提高,从而提高了催化剂活性。太阳光降解甲基橙溶液结果表明,TiO_2-B-S活性明显高于单一B、S掺杂改性催化剂,共掺杂改性对提高TiO_2可见光活性具有协同效应。     

TiO2超声光催化降解荧光增白剂-CBW

均匀沉淀法制备了纳米TiO2，TEM，xRD分别进行了表征。以该纳米TiO2为光催化剂，对超声光催化降解荧光增白剂CBw的反应进行了研究。结果表明，超声波的引入提高了纳米TiO2光催化降解CBw的反应效率；反应符合Langmuir-Hinshelwood动力学模型，表观反应速率常数k1为0．0266min^-1；反应受超声波功率的影响；溶液中添加少量的Fe^3 ，H3PW12O40、H2O2均能够明显地强化CBw的降解反应。     

原位刻蚀法制备TiO2纳米线阳极薄膜

采用水热法在FTO基板上制备Ti O2纳米线阵列,在此基础上,通过水热法采用HCl对该薄膜进行原位刻蚀。XRD结果表明刻蚀过程并未影响Ti O2纳米线阵列薄膜的结晶性。SEM结果表明刻蚀过程能有效降低纳米线之间的团聚程度,从而保证薄膜具有较大的比表面积。染料的吸附-脱附结果也表明,刻蚀后纳米线薄膜的染料负载能力提高了1倍,将制备的Ti O2纳米线阵列薄膜作为染料敏化太阳电池的光阳极进行光电性能研究,发现使用经过刻蚀处理光阳极的太阳电池比采用未刻蚀处理的光阳极薄膜的电池光电转换效率提高了6倍。