Pt/TiO2光诱导催化重整乙醇制氢

对无氧条件下Pt/TiO2光诱导催化重整乙醇制氢进行了系统的研究，结果表明，乙醇的光催化重整制氢反应受催化剂表面化学状态，反应体系的pH值，浓度的影响较大，而受反应体系温度的影响较小，在运动XRD，XPS，HNMR等技术手段对催化剂和反应产物进行表征，分析的基础上，提出了无氧条件下乙醇光催化重整制氢可能的反应机理。     

几种低碳醇在Pt／TiO2上的光催化产氢速率的研究

主要考察了无氧条件下低碳醇（甲、乙、丙醇）在Pt/TiO2表面光催化重整反应制氢。深入探讨了几种低碳醇与其放氢速率的构-效关系,提出了低碳醇在Pt/TiO2光催化剂表面吸附态的模型。     

A Dewetted‐Dealloyed Nanoporous Pt Co‐Catalyst Formed on TiO2 Nanotube Arrays Leads to Strongly Enhanced Photocatalytic H2 Production

Pt nanoparticles are typically decorated as co‐catalyst on semiconductors to enhance the photocatalytic performance. Due to the low abundance and high cost of Pt, reaching a high activity with minimized co‐catalyst loadings is a key challenge in the field. We explore a dewetting‐dealloying strategy to fabricate on TiO₂ nanotubes nanoporous Pt nanoparticles, aiming at improving the co‐catalyst mass activity for H₂ generation. For this, we sputter first Pt‐Ni bi‐layers of controllable thickness (nm range) on highly ordered TiO₂ nanotube arrays, and then induce dewetting‐alloying of the Pt‐Ni bi‐layers by a suitable annealing step in a reducing atmosphere: the thermal treatment causes the Pt and Ni films to agglomerate and at the same time mix with each other, forming on the TiO₂ nanotube surface metal islands of a mixed PtNi composition. In a subsequent step we perform chemical dealloying of Ni that is selectively etched out from the bimetallic dewetted islands, leaving behind nanoporous Pt decorations. Under optimized conditions, the nanoporous Pt‐decorated TiO₂ structures show a>6 times higher photocatalytic H₂ generation activity compared to structures modified with a comparable loading of dewetted, non‐porous Pt. We ascribe this beneficial effect to the nanoporous nature of the dealloyed Pt co‐catalyst, which provides an increased surface‐to‐volume ratio and thus a more efficient electron transfer and a higher density of active sites at the co‐catalyst surface for H₂ evolution.     

以葡萄糖和蔗糖为电子给体在Pt/TiO2上光催化制氢

以Pt/TiO2为催化剂, 研究了以葡萄糖和蔗糖为电子给体的光催化制氢反应以及有机物自身的去除效果.     

乙烯在Pt/Pt4+-TiO2上的可见光降解

以TiO2为主的光催化氧化技术存在太阳能利用率低(～5％)和光量子转化效率低(～4％)等缺点，使其工业应用受到制约，人们尝试用过渡金属离子掺杂和贵金属表面修饰等技术来提高催化剂对太阳能的利用率和光量子的转化效率，但目前将铂离子掺杂和铂金属表面修饰技术结合用于光催化     

Template‐free Fabrication of Hierarchical Macro‐/mesoporous N‐doped TiO2/graphene Oxide Composites with Enhanced Visible‐light Photocatalytic Activity

Hierarchical macro‐/mesoporous N‐doped TiO₂/graphene oxide (N‐TiO₂/GO) composites were prepared without using templates by the simple dropwise addition mixed solution of tetrabutyl titanate and ethanol containg graphene oxide (GO) to the ammonia solution, and then calcined at 350 °C. The as‐prepared samples were characterized by scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under visible‐light irradiation. The results show that N‐TiO₂/GO composites exhibited enhanced photocatalytic activity. GO content exhibited an obvious influence on photocatalytic performance, and the optimal GO addition content was 1 wt%. The enhanced photocatalytic activity could be attributed to the synergetic effects of three factors including the improved visible light absorption, the hierarchical macro‐mesoporous structure, and the efficient charge separation by GO.     

Double‐Side Co‐Catalytic Activation of Anodic TiO2 Nanotube Membranes with Sputter‐Coated Pt for Photocatalytic H2 Generation from Water/Methanol Mixtures

Self‐standing TiO₂ nanotube layers in the form of membranes are fabricated by self‐organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt‐decorated membranes are transferred either in tube top‐up or in tube top‐down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H₂ generation using either front or back‐side light irradiation. Double‐side Pt‐decoration of the tube membranes leads to higher H₂ generation rates (independently of tube and light‐irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect cannot be only ascribed to the overall amount of Pt co‐catalyst as such but also to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes acts as light‐harvesting zone and electrons therein generated can diffuse towards the Pt/TiO₂ active zones (tube extremities) where they can react with the environment and generate H₂.     

冷等离子体处理制备NiO/SrTiO3及其光催化水分解制氢性能研究

利用辉光放电等离子体处理改进常规浸渍法制备了NiO/SrTiO3光催化剂. XRD、XPS和TEM分析证明, 金属颗粒在载体表面的分散性得到极大提高, 并在反应中具有很好的稳定性. XPS、热重和XRD分析表明, 等离子体处理使浸渍的Ni(NO3)2在常温下分解为晶化度较低的NiO团簇, 该团簇可能与载体具有较强的相互作用. 在光催化反应中, 高分散的金属可以促进电荷传递, 并提供更多的表面活性位. 对于水分解制氢和甲醇溶液转化制氢反应, 该催化剂的活性分别是常规催化剂的1.3倍和1.8倍.     

Water oxidation on N‐Doped TiO2 nanotube arrays

Photocatalytic splitting water into hydrogen and oxygen by utilizing solar energy is regarded as an effective strategy to solve oil crisis. By utilizing density functional calculations, we herein present the systemic studies with respect to water splitting mechanism on N‐doped TiO₂ nanotube arrays (NTAs), and focus on activation energy, thermodynamic properties, and effects of N‐doping on reaction process. Our results reveal that the impurity 2p states of doped nitrogen effectively change electronic structure of TiO₂ NTAs, which act as an electron acceptor and facilitate weakly bound electrons of valence band to be easily excited to acceptor level, as well as enhance the first H₂O adsorption and dissociation on the inside wall of N‐doped TiO₂ NTAs. Therefore, it is found that the rate‐determining step of water splitting is the formation reaction of HOO* on N‐doped TiO₂ NTAs rather than the formation of HO* from the first H₂O. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

利用甘油废水Pt/TiO2光催化制氢

研究了以甘油为电子给体在Pt/TiO2上光催化生成氢的反应.结果表明甘油能显著地提高光催化放氢效率,并且其自身的降解活性也很好.研究了反应时间、甘油起始浓度、溶液pH值、甘油废水中共存物对光催化放氢的影响.甘油光催化降解最终产物是H2O和CO2,检测到了甘油醛、羟基乙醛、羟基乙酸、甲醛等中间产物.探讨了可能的反应机理.     

脉冲沉积制备Cu_2O/TiO_2纳米管异质结的可见光光催化性能

在用阳极氧化法制备有序排列TiO2纳米管阵列薄膜的基础上,引入脉冲沉积工艺,成功实现了均匀、弥散分布的Cu2O纳米颗粒修饰改性TiO2纳米管阵列,形成Cu2O/TiO2纳米管异质结复合材料.利用场发射扫描电镜(FESEM)、场发射透射电镜(FETEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和紫外-可见漫反射光谱(UV-Vis DRS)对样品进行表征,重点研究了Cu2O/TiO2纳米管异质结的光电化学特性和对甲基橙(MO)的可见光催化降解性能.结果表明,Cu2O纳米颗粒均匀附着在TiO2纳米管阵列的管口和中部位置,所制备的Cu2O/TiO2纳米管异质结具有高效的可见光光催化性能;在浓度为0.01 mol?L-1的CuSO4溶液中制得的Cu2O/TiO2纳米管异质结表现出最好的电化学特性和光催化性能;另外,对Cu2O纳米颗粒影响光催化活性的机理进行了讨论.     

双介孔结构的纳米TiO2/I2复合材料的制备及其可见光催化性能

以钛酸丁酯为前驱体,碘溶胶为碘源,在室温下采用水解沉淀法制备了单质碘和纳米TiO2复合的双介孔结构光催化剂(M-I2-TiO2).采用X射线衍射(XRD)、透射电子显微镜(TEM)、比表面分析(BET)、紫外-可见(UV-Vis)漫反射光谱和傅里叶变换-红外光谱(FT-IR)对M-I2-TiO2进行了表征.以次甲基蓝(MB)溶液为模拟废水,对M-I2-TiO2的光催化性能进行了评价,研究了不同热处理温度对光催化活性的影响.结果表明,M-I2-TiO2在可见光区有显著的吸收,300℃热处理得到的样品比表面积高达227.6 m2/g,600℃热处理所得样品的比表面积仍高达111.8 m2/g,而400℃热处理所得样品具有最好的光催化降解性能.双介孔结构纳米TiO2/I2复合材料的光催化降解性能显著高于相同方法制备的纯TiO2和Degussa P-25商业产品.催化剂经6次重复使用其光催化活性基本保持不变.     

TiO2/Bi2O3纳米复合体的制备及可见光催化产氢性能

首先采用相分离的水解-溶剂热法制备了Bi₂O₃纳米粒子,然后利用简单的湿化学法在Bi₂O₃表面负载不同比例的TiO₂纳米颗粒,进而得到TiO₂/Bi₂O₃纳米复合体。通过气氛调控的表面光电压谱(SPS)等测试表明,表面负载适量的TiO₂后能够提高Bi₂O₃光生电荷分离。可见光催化产氢和降解污染物测试结果进一步证明,表面负载适量的TiO₂后可显著提高其可见光催化活性,其中Ti/Bi摩尔比为7%时具有最高的光催化活性。这主要归因于TiO₂具有较为合适的导带能级位置,可以接收Bi₂O₃在可见光激发下所产生的高能级电子,从而抑制光生电子-空穴对复合,并且维持了高能级电子较高的还原能力。     

Understanding the Photocatalytic Properties of Pt/CeOx/TiO2: Structural Effects on Electronic and Optical Properties

Ceria-titania interfaces play a crucial role in different chemical processes but are especially promising for the photocatalytic splitting of water using light in the visible wavelength region when Pt is added to the system. However, the complexity of this hierarchical structure hampers the study of the origin of its outstanding properties. In this article, the structural, electronic and optoelectronic properties of CeO₂/TiO₂ systems containing 1D, 2D, and 3D particles of ceria are analyzed by means of density functional calculations. Adsorption sites and vacancy effects have been studied to model Pt adsorption. Density of states calculations and absorption spectra simulations explain the behavior of these systems. Finally, these models are used for the screening of other metals that can be combined with this heterostructure to potentially find more efficient water splitting photocatalysts.     

TiO2基光解水析氢非贵金属共催化剂的研究

利用太阳能光催化水解制氢是获得清洁、廉价、无污染的氢气最有前景的一种方式。这个过程主要包括三个步骤：太阳光的捕获,电荷分离与转移,催化质子还原产生氢气。其中,大量的研究工作主要集中在前两步,对于第三步的研究则相对较少。然而,共催化剂的引入可以有效促进光催化活性并提高氢气产生速率。共催化剂主要分为贵金属共催化剂和非贵金属共催化剂,其中,贵金属共催化剂有着较高的活性,但是其价格及来源限制了其实际应用,因此开发廉价高效的非贵金属共催化剂非常重要。本文对TiO₂基光解水析氢的非贵金属共催化剂（过渡金属单质及其复合物以及非金属碳基材料）进行了总结,详细讨论了不同共催化剂的作用机理,并对共催化剂的发展方向进行了合理展望。     

Photocatalytic Activity of Fe and Ce Co‐doped Mesoporous TiO2 Catalyst under UV and Visible Light

The catalysts of un‐doped, single‐doped and co‐doped mesoporous titanium dioxide (MTiO₂) were prepared by a template method with tetrabutyltitanate (Ti(OC₄H₉)₄) as a Ti source material and Pluronic P123 as a template. The photo‐absorbance of the obtained catalysts was measured by UV‐vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange (MO) (50 mg/L) in an aqueous solution. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The effect of Fe and Ce co‐dopants on the material properties was investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption‐desorption isotherm measurement. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The photocatalytic activity of MTiO₂ co‐doped with Fe and Ce was markedly improved due to the synergistic actions of the two dopants.     

AgBr/TiO2复合催化剂:双注法制备及其可见光催化性能

以TiO₂为载体,采用双注法合成了AgBr/TiO₂复合光催化剂.利用X射线衍射仪(XRD)、紫外可见分光光度计(UV-Vis)和扫描电子显微镜(SEM)对AgBr/TiO₂的结构、光吸收、形貌进行了表征.研究了AgBr/TiO₂在可见光下对甲基橙和丁基罗丹明B的光催化活性.结果表明,与TiO₂相比,AgBr/TiO₂的光吸收范围拓展到400—600nm波段,并且随着AgBr负载量的增加,AgBr/TiO₂的可见光吸收强度增强;当AgBr与TiO₂的摩尔比为0.25时,AgBr/TiO₂具有最大催化活性;在相同条件下,AgBr/TiO₂对丁基罗丹明B的降解效果优于甲基橙.     

In离子掺杂二氧化钛纳米管可见光催化活性的研究

采用两步预掺杂方法制备出In离子掺杂二氧化钛纳米管可见光催化剂. 可见光催化降解对氯苯酚实验证明: 掺杂In离子量为3%的TiO2纳米管可见光活性最高, 是纯TiO2纳米管的2倍以上. X射线衍射(XRD), X光电子能谱(XPS)和表面光电压谱(SPS)结果表明: 当In离子掺杂浓度较小时, In离子取代晶格Ti的位置形成InxTi1－xO2取代式掺杂结构. In离子的掺杂能级与Ti离子的3d轨道形成混合价带, 使禁带宽度变窄, 增强了可见光响应. 随着In离子掺杂浓度的增加, 同时在InxTi1－xO2纳米管表面生成In2O3, 形成InxTi1－xO2/In2O3纳米管复合结构. 该复合结构有效地增加可见光响应, 促进了光生载流子的分离, 提高了光生载流子在固/液界面参加光催化反应的利用率, 使纳米管催化剂可见光催化活性显著提高.     

TiO_2(B)纳米带光催化剂的制备及分解水产氢性能

经过钛酸四丁酯强碱溶液中水解→水热→质子交换→焙烧路线制备出Ti O2(B)纳米带.采用HRTEM、FESEM、XRD、UV-Vis、BET和光解水产氢反应等对催化材料的微观表面结构、光吸收性能以及光催化性能进行了研究.结果表明:该路线制备的Ti O2(B)纳米带反应条件温和,便于大批量合成.通过改变实验参数实现晶型结构和微观形貌的调变,且不同晶型结构和微观形貌的材料进行光催化分解水产氢活性对比,它们的活性顺序为:NaxH2-xTi3O7·n H2纳米管Ti O2(B)Ti O2(anatase)Na2Ti6O13,表明Ti O2(B)纳米带是一类较好的光催化分解水制氢半导体材料.提出了Ti O2(B)纳米带的可能经历了Na2Ti3O7→H2Ti3O7→H2Ti6O13→H2Ti12O25→Ti O2(B)的形成过程.     

不同染料共敏化TiO2可见光分解水产氢性能研究

以光催化还原水制氢为指标反应系统地考察了若干种染料对TiO2的共敏化作用,研究表明曙红Y(EosinY,EY)和玫瑰红(Rose Bengal,RB)对TiO2的共敏化效果最为显著,而钌染料(Ru(bipy)3Cl2,Ru)分别与EY和RB的共敏化效果则不显著或没有共敏化效应.UV-Vis吸收光谱和荧光光谱技术对染料共敏化体系的表征结果表明,在EY/RB体系中显著的共敏化效应不仅与染料对可见光的吸收增加有关,而且还与染料分子之间的荧光共振能量转移(FRET)有关,这种荧光共振能量转移可有效降低染料激发态由于荧光猝灭导致的能量损失,提高光催化产氢效率.瞬态光电流实验和单色光产氢实验结果也进一步确证了这种作用.我们的研究结果还表明,在Ru/EY和Ru/RB体系中,必须加入甲基紫精作为电子中继试剂才能使催化剂具有光催化活性.在优化的反应条件下(λ≥420 nm),EY/RB共敏化体系的产氢量子效率分别比EY和RB单一染料敏化体系提高了36.3%和215.4%.