四羟基苯基金属卟啉（MTHPP）／TiO2的合成及其光催化活性的研究

采用Alder法合成四羟基苯基卟啉,并用四种醋酸盐：醋酸锌,醋酸镍,醋酸铜,醋酸钴与原卟啉合成了相应4种金属卟啉（MTHPP）．采用金属卟啉为敏化剂,并与蒸汽热法制备的纯锐钛矿型TiO2作用,得到相应的金属卟啉敏化TiO2复合光催化剂．利用红外、紫外、SEM、和XRD对所得金属卟啉以及金属卟啉-TiO2复合光催化剂进行了表征和分析．结果表明,所合成的金属卟啉均为目标化合物,金属卟啉负载于TiO2表面,未改变TiO2的晶型和形貌．金属卟啉与TiO2之间存在氢键的作用力．可见光降解亚甲基蓝（MB）实验结果表明,用锌卟啉（ZnTHPP）敏化的复合催化剂性能最好,复合催化剂性质稳定,可重复使用多次．     

Phase-selectivity photocatalysis: a new approach in organic pollutants' photodecomposition by nanovoid core(TiO2)/shell(SiO2) nanoparticles

Core(TiO(2))/shell(SiO(2)) nanoparticles, with a void layer between the TiO(2) core and the silica layer, act as phase-selectivity photocatalysts for the photodecomposition of organic pollutants (gas phase) without any damage to their organic supports (solid phase).     

Comparative Study of Homogeneous and Heterogeneous Photocatalytic Redox Reactions: PW(12)O(40)(3-) vs TiO(2)

Polyoxometalates (POMs) as a homogeneous photocatalyst and semiconductor oxide as a heterogeneous photocatalyst share many aspects of similarity in their operating mechanisms. This study systematically compares various photocatalytic oxidation and reduction reactions of PW12O403- (a POM) and TiO2 in water to demonstrate that the two photocatalysts are very different in many ways. Both POM and TiO2 can photooxidize various organic compounds with comparable rates, but the POM-mediated mineralization is markedly slower than the mineralization with TiO2 under the experimental conditions employed in this study. Kinetic studies using tert-butyl alcohol as an OH radical scavenger suggest that OH radicals are the sole dominant photooxidant in POM-mediated degradations regardless of the kind of substrates tested, whereas both OH radicals and direct hole transfers take part in TiO2 photocatalysis. POM immobilization on silica support and surface fluorination of TiO2 significantly modified the kinetics and intermediate distribution. POM-mediated photoreductive dechlorination of CCl4 and trichloroacetate was negligible, whereas the dechlorination with TiO2 was markedly faster. The rate of electron transfer from POM- to reducible substrates seems to be significantly slower than the rate of conduction band electron transfer on TiO2 mainly due to the strong electron affinity of POM. The effects of H2O2 addition on photocatalytic reactivity are also very different between POM and TiO2. Detailed kinetic and mechanistic comparisons between PW12O403- and TiO2 photocatalysts are presented and discussed to understand the similarities and differences.     

B掺杂TiO2/AC光催化剂的制备及活性

以硼酸和钛酸丁酯为主要原料，以活性炭(AC)为载体。用溶胶-凝胶法制备了B掺杂TiO2／AC光催化剂．用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV—VIS)对制得的光催化剂进行了表征．以甲基橙水溶液的光催化脱色反应和氧化乐果水溶液的光催化降解反应。考查了不同B掺杂TiO2／AC光催化剂的活性．结果表明，所有B掺杂TiO2／AC光催化剂均为锐钛矿晶相．B的掺杂未导致TiO2／AC光催化剂的吸收带边发生明显的移动．当B-TiO2质量分数分别为2．0％和2．5％时，TiO2／AC光催化剂的活性有明显的提高．B-TiO2质量分数2．0％时活性最高．但是，当B-TiO2质量分数分别为1．5％和3．0％时。TiO2／AC光催化剂的活性降低．B的缺电子特性可能改变了TiO2能带中的电子密度，使光催化反应中光生电子和空穴的俘获方式发生变化；同时。B的缺电子特性也会使光催化剂表面的Lewis酸强度增强，导致表面吸附OH-数量和目标反应物的吸附方式发生变化．这些可能是B-TiO2／AC光催化剂活性发生变化的主要原因．     

Cobalt Ion-Doped TiO(2) Photocatalyst Response to Visible Light

Photocatalytic activity under visible light irradiation was generated by doping a small amount of Co(2+) ions into TiO(2) particles. Nanometer-sized particles with the composition xCoO-(100-x) TiO(2) (xCo/TiO(2); 0300 nm) light irradiation but also induced the visible light (lambda>400 nm) response. The highest photocatalytic activities were obtained at x=0.03 for both irradiations. Copyright 2000 Academic Press.     

炭气凝胶孔结构对其负载的TiO2光催化降解甲基橙性能的影响

选用两种孔径不同的炭气凝胶CA125和CA500制备了碳含量为20%的TiO2/CA光催化剂,采用X射线衍射、扫描电镜和N2吸附-脱附对催化剂进行了表征,并考察了其光催化降解甲基橙反应性能.结果表明,TiO2/CA样品中TiO2主要以锐钛矿相存在,伴随有少量的金红石相,且均匀分散于炭气凝胶的表面.催化剂的孔隙率分析表明,孔结构直接影响到催化剂的光催化活性,以中孔为主的TiO2/CA125活性要远高于TiO2/CA500.这主要源于中孔良好的吸附性能及其合适的空间限域效应.     

Mg-Al 类水滑石/二氧化钛异质复合纳米晶光催化氧化苯的性能

 采用过饱和沉淀法合成 n(Mg)/n(Al) = 2 的 Mg-Al 类水滑石化合物 (Mg-Al-HT), 再用水热法将它与钛胶复合, 制得 Mg-Al-HT/TiO2 异质复合光催化剂. 采用 X 射线粉末衍射、透射电子显微镜、场发射扫描电子显微镜、低温 N2 吸附-脱附、紫外-可见漫反射光谱和热重等技术对催化剂结构、成分和性质进行了表征. 结果表明, 在波长 365 nm 的紫外光照射降解苯的反应中, Mg-Al-HT/TiO2 异质复合光催化剂表现出优于单一的 TiO2 或 Mg-Al-HT 催化剂的光催化活性, 且稳定性更高; 同时讨论了该复合催化剂性能优异的原因. 另外, 运用电子顺磁共振技术检测到体系中存在羟基自由基等活性物种, 并据此提出了 Mg-Al-HT/TiO2 异质复合纳米晶催化剂光催化降解苯的反应机理.     

Density functional theory study of CO catalytic oxidation on Co_2B_2/TiO_2（110） surface

Titanium dioxide with CoB amorphous alloys nanoparticles deposited on the surface is known to exhibit higher catalytic activity than the CoB amorphous. A study of the structure of such system is necessary to understand this effect. A quantum chemical study of Co2B2 on the TiO2 (110) surface was studied using periodic slab model within the framework of density functional theory (DFT). The results of geometry optimization indicated that the most stable model of adsorption was Co2B2 cluster adsorbed on the hollow site of TiO2.The adsorption energy calculated for Co2B2 on the hollow site was 439.3 kJ/mol.The adsorption of CO and O2 was further studied and the results indicated that CO and O2 are preferred to adsorb on the Co2 site. Co-adsorption of CO and O2 shows that Co2B2/TiO2 is a good catalyst for the oxidation of CO to carbon dioxide in the presence of oxygen.     

Photocatalytic degradation of methyl orange over metalloporphyrins supported on TiO2 Degussa P25

The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO(2) (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV (DRS-UV-vis) and infrared spectra. Copper porphyrin-sensitized TiO(2) photocatalyst (CuP-TiO(2)) showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO) charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO(2) catalyst due to the increase of induced interactions.     

掺杂纳米TiO2光催化性能的研究

利用浸渍法分别制备了Cr、Mn、Fe、Co、Ni、Cu六种过渡金属离子掺杂改性的二氧化钛光催化剂，以乙酸水溶液的光催化氧化反应和二氧化碳还原反应为探针,评价了掺杂催化剂的光催化性能.借助光电子能谱（XPS）、X射线衍射分析（XRD）等手段对掺杂催化剂进行了表征.研究结果表明，经过渡金属离子掺杂后，光催化性能均有不同程度的改善，改善程度按Cr、Co、Ni、Fe、Mn、Cu递增.掺杂后催化剂表面吸附氧的活泼性、金属离子的价态及得电子能力上的差异决定了不同离子掺杂纳米二氧化钛光催化性能的差异.     

Fe3+掺杂TiO2光催化降解聚乙烯薄膜的研究

以快速溶胶-凝胶法制备了纳米TiO2光催化剂,并用Fe3 对其掺杂改性,在室温条件下,用于固相光催化降解聚乙烯(PE)包装薄膜的研究.对催化剂和薄膜进行了X衍射分析(XRD)、傅立叶红外光谱分析(FT-IR)、扫描电子显微镜(SEM)形貌观察.结果表明,60W紫外光辐射240h后,PE失重为8.43%,锐钛矿型纳米TiO2光催化剂使PE失重30.66%;用Fe3 掺杂后,0.5?2O3/TiO2、1.0?2O3/TiO2和2.0?2O3/TiO2分别使PE失重35.91%、20.72%和13.30%.光催化剂加速了PE的失重,碳链的断裂和光氧化腐蚀,在薄膜表面形成大量的坑洞,降解产物中的小分子量的石蜡含量明显增高.Fe3 掺杂有一个最佳量,0.5?2O3/TiO2光催化降解PE的活性最高.     

二氧化钛基Z型光催化剂综述(英文)

TiO_2具有无毒、耐腐蚀、高稳定和低成本等特点,已被广泛应用于光催化领域.然而,TiO_2的禁带较宽,只能吸收仅占太阳光4%的紫外光部分,从而严重限制了TiO_2光催化材料对太阳光的有效应用.目前很多方法被用来提高TiO_2光催化效率,如金属/非金属掺杂、贵金属负载、异质结构建和与碳材料复合等,这些策略在提高光催化剂的光催化效率中,涉及到如何兼顾太阳光利用和光生空穴和电子氧化还原能力两者之间的平衡.通常,半导体禁带宽度越窄,半导体的光谱响应范围越宽、太阳光利用越多,但光生空穴和电子氧化还原能力越弱.因此,想要提高TiO_2的光催化性能,应考虑以下两个方面的平衡:即降低带隙宽度,拓展半导体的光谱响应范围;与之同时使价带电位更正,导带电位更负之间的平衡.然而,这两个点是相互矛盾的,因此很难在单组分光催化剂中同时实现这两点.然而,Z型光催化剂可以同时满足这两点要求,即:降低半导体的带隙,同时使导带更负,价带更正,因为Z光催化系统利用了两种半导体的优势,其电荷转移机制类似于自然界中绿色植物的光合作用,其中的载流子传输途径包括两步激发,类似于英文字母"Z",Z型光催化剂因此而得名.Z型光催化剂既能保留较高还原能力的光生电子和又能保留较高氧化能力的光生空穴,由于Z型光催化剂特有的优点,在光催化领域的应用越来越广泛.本文综述了TiO_2基Z型光催化剂的最新研究进展,其中包括:Z型光催化机理、应用范围和光催化活性改进方法.Z型光催化剂分为传统液相Z型光催化体系,全固态Z型光催化体系,以及最近几年发展起来的直接Z型光催化体系.它们的主要应用包括:光催化分解水产氢、二氧化碳还原制备太阳燃料、有机污染物光催化降解.论文进一步讨论了提高TiO_2基Z型光催化剂性能的方法,包括pH值调控、电子导体选择、助催化剂使用、掺杂改性、组织形貌控制、两种半导体质量比优化等.最后,提出了TiO_2基Z型光催化剂今后面临的挑战和发展前景展望.     

One-step and self-assembly based fabrication of Pt/TiO2 nanohybrid photocatalysts with programmed nanopatterns

Hybrid Pt/TiO(2) nanostructures with diverse morphologies from nanodot, nanowire to mesoporous structures were obtained by a one-step synthesis based on block copolymer self-assembly. The structural transformation was easily tuned by controlling the relative amount of TiO(2) sol-gel precursor to poly(styrene-block-ethylene oxide) diblock copolymer (PS-b-PEO). These Pt/TiO(2) nanocomposites were utilized as photocatalysts with enhanced activity via synergistic coupling. Key parameters including the amount of TiO(2), types of morphology of photocatalysts, and the platinization of TiO(2) discussed in this study affected photocatalytic performance given that the hybrids were well-dispersed in nanopatterned configurations.     

磁载WO3－TiO2／SiO2／Fe3O4复合光催化剂的制备及其光催化活性

 用溶胶－凝胶法在表面包覆了SiO2的磁基体Fe3O4上负载TiO2,从而得到了易于磁性固液分离的磁载WO3－TiO2／SiO2／Fe3O4复合光催化剂,并通过IR,XRD,SEM和XPS等测试手段对催化剂进行了表征．研究了磁载WO3－TiO2／SiO2／Fe3O4复合光催化剂对亚甲基蓝溶液脱色的性能,并考察了WO3掺杂量对样品催化活性的影响．结果表明,n（WO3）／n（TiO2）＝0．001时,磁载WO3－TiO2／SiO2／Fe3O4复合光催化剂的催化活性最高,循环使用3次时脱色率仍保持在98％．     

铋改性TiO2单晶光催化剂的制备及其完全去除酚类污染物

伴随着人类社会生产生活需要,工业污水中酚类物质的存在极易污染表面水、地下水甚至饮用水.然而,传统污水处理工艺无法对其实现完全去除,更因其稳定的化学结构和难降解特性,对生态系统和人类健康构成了巨大威胁.因此,寻求完全去除水体中酚类污染物是目前环境领域中重要的研究课题之一.二氧化钛因具有优越的物理、化学和光学性能,而被广泛应用于污染物降解研究,然而,传统TiO2光催化剂由于可见光吸收弱和光生电荷高复合率,导致污染物降解效率低,尤其是针对难降解有机污染物如酚类难以实现高效的去除.为此,本文通过引入铋纳米粒子作为TiO2单晶的改性剂,通过充分发挥铋纳米粒子的LSPR效应和TiO2单晶结构的高传导率,不仅有效地拓宽了TiO2的光响应范围(~2.8 eV),而且提高了光生电荷的分离效率,导致其优越的光催化行为.酚类污染物的降解实验表明,所合成的Bi-SCTiO2光催化剂在模拟太阳光照射下,能完全去除水体中的苯酚和对硝基酚,克服了现有以TiO2为基础的光催化剂无法实现酚类污染物完全去除的缺点.更重要的是,当使用环境水如自来水或矿泉水配制苯酚溶液,所制备的Bi-SCTiO2光催化剂仍能实现苯酚的高效降解(>98%);即使采用含有大量有机物质和微生物的长江水所配制的苯酚溶液,在模拟太阳光照射下,Bi-SCTiO2光催化剂对苯酚的降解率仍然高达96%.进一步研究发现,在各种无机离子如Na^+,K^+,Ca^2+,Cl^?,HCO3^?或SO4^2?(0.1 mM)的干扰下,制备的Bi-SCTiO2对苯酚降解率仍然高达98%以上.光催化循环实验表明,所制备的Bi-SCTiO2循环四次后,其对苯酚的降解率几乎保持不变,说明Bi-SCTiO2具有极好的循环稳定性.运用ESR和MS等分析手段,确定了酚类污染物降解的中间体结构、形态和降解路径,再结合Bi-SCTiO2催化剂的光电性能和自由基诱捕实验,提出了酚类污染物完全降解的机理.     

Adsorption of Co2B2 and Ni2B2 Clusters on the TiO2 (110) Surface: a Density Functional Study

Based on density functional theory and generalized gradient approximation calculations, the adsorption of Co2B2 and Ni2B2 clusters on the rutile TiO2 (110) surface has been investigated utilizing periodic supercell models. Unambiguously, the results demonstrate that the hollow site turns out to be preferable for Co2B2 cluster while Ti2 site is for Ni2B2 cluster to adsorb. Orbital population analysis indicates a strong interaction between Co2B2 and O atom of TiO2 surface, which can be attributed to the overlap of Co 3d and surface O 2p orbital. Similarly, for Ni2B2 , the bonding interaction occurs mostly through the interaction of Ni 3d/4s and O 2p orbitals. Note that, there is also an interaction within the Co2B2 clusters (Ni2B2) through B 2s/2p and Co 3d orbitals (Ni 3d/4s). Moreover, orbital analysis results shows that the strong bonding between Ni2B2 and Ti2 site is due to the overlap of HOMO of Ni2B2 and d-orbital of five-coordinated titanium atoms.     

TiO2/活性炭负载型光催化剂的溶胶-凝胶法合成及表征

以钛酸四丁酯为钛源,采用溶胶-凝胶法在多孔活性炭(AC)表面合成TiO2前驱体,在氮气保护下程序升温处理制得TiO2/AC负载型光催化剂.采用X射线衍射、漫反射光谱、傅里叶变换红外光谱、扫描电镜、能量色散谱和低温液氮吸附等对光催化剂晶相结构、光谱特征及表面结构进行了表征.结果表明,AC可提高TiO2分散性能,降低TiO2团聚体的尺寸,并抑制其由锐钛矿相向金红石相的转变.TiO2与AC接触界面处有Ti-O-C键生成.另外,AC的含量对TiO2的能阈结构和晶粒大小影响不大.苯酚溶液的光催化降解测试结果表明,AC负载可为TiO2提供高浓度反应环境,适宜量的负载可显著提高TiO2对有机稀溶液的光催化降解活性.对于50mg/L苯酚的光催化降解,AC的质量分数分别为5%,9%和11%时催化剂协同系数分别为1.1,1.5和1.3.循环使用7次后,AC含量为9%的催化剂对苯酚的降解率仍达95.84%.     

Integration of [(Co(bpy)3]2+ Electron Mediator with Heterogeneous Photocatalysts for CO2 Conversion

An efficient chemical system for electron generation and transfer is constructed by the integration of an electron mediator ([Co(bpy)₃]²⁺; bpy=2,2′‐bipyridine) with semiconductor photocatalysts. The introduction of [Co(bpy)₃]²⁺ remarkably enhances the photocatalytic activity of pristine semiconductor photocatalysts for heterogeneous CO₂ conversion; this is attributable to the acceleration of charge separation. Of particular interest is that the excellent photocatalytic activity of heterogeneous catalysts can be developed as a universal photocatalytic CO₂ reduction system. The present findings clearly demonstrate that the integration of an electron mediator with semiconductors is a feasible process for the design and development of efficient photochemical systems for CO₂ conversion.     

Roles of electrolytes on charge recombination in dye-sensitized TiO(2) solar cells (2): the case of solar cells using cobalt complex redox couples

Dye-sensitized solar cells (DSC) were prepared from nanoporous TiO(2) electrodes with two different cobalt complex redox couples, propylene-1,2-bis(o-iminobenzylideneaminato)cobalt(II) {Co(II)(abpn)} and tris(4,4'-di-tert-buthyl-2,2'-bipyridine)cobalt(II) diperchlorate {Co(II)(dtb-bpy)(3)(ClO(4))(2)}. The performances of the DSCs were examined with varying the concentrations of the redox couples and Li cations in methoxyacetonitrile. Under 1 sun conditions, short-circuit currents (J(sc)) increased with the increase of the redox couple concentration, and the maximum J(sc) was found at the Li(+) concentration of 100 mM. To rationalize the observed trends of J(sc), electron diffusion coefficients and lifetimes in the DSCs were measured. Electron diffusion coefficients in the DSCs using cobalt complexes were comparable to the previously reported values of nanoporous TiO(2). Electron lifetime was independent of the concentration of the redox couples when the concentration ratio of Co(II)(L) and Co(III)(L) was fixed. With the increase of Li(+) concentration, the electron lifetime increased. These results were interpreted as due to their slow charge-transfer kinetics and the cationic nature of Co complex redox couples, in contrast to the anionic redox couple of I(-)/I(3)(-). The increase of the lifetimes with Li(+) was interpreted with the decrease of the local concentration of Co(III) near the surface of TiO(2). The addition of 4-tert-butylpyridine (tBP) with the presence of Li(+) increased J(sc) significantly. The observed increase of the electron lifetime by tBP could not explain the large increase of J(sc), implying that tBP facilitates the charge transfer from Co(II)(L) to dye cation, with the association of the change of the reorganization energy between Co(II) and Co(III).