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1.
Hydrogenated Anatase: Strong Photocatalytic Dihydrogen Evolution without the Use of a Co‐Catalyst
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Dr. Ning Liu Christopher Schneider Dr. Detlef Freitag Dr. Umamaheswari Venkatesan Dr. V. R. Reddy Marthala Prof.Dr. Martin Hartmann Benjamin Winter Prof.Dr. Erdmann Spiecker Dr. Andres Osvet Eva M. Zolnhofer Prof.Dr. Karsten Meyer Dr. Tomohiko Nakajima Xuemei Zhou Prof.Dr. Patrik Schmuki 《Angewandte Chemie (International ed. in English)》2014,53(51):14201-14205
The high‐pressure hydrogenation of commercially available anatase or anatase/rutile TiO2 powder can create a photocatalyst for H2 evolution that is highly effective and stable without the need for any additional co‐catalyst. This activation effect cannot be observed for rutile; however, for anatase/rutile mixtures, a strong synergistic effect can be found (similar to results commonly observed for noble‐metal‐decorated TiO2). EPR and PL measurements indicated the intrinsic co‐catalytic activation of anatase TiO2 to be due to specific defect centers formed during hydrogenation. These active centers can be observed specifically for high‐pressure hydrogenation; other common reduction treatments do not result in this effect. 相似文献
2.
Zhensheng Hong Yuxia Xu Yubin Liu Prof. Mingdeng Wei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(34):10753-10760
Unique ordered TiO2 superstructures with tunable morphology and crystalline phase were successfully prepared by the use of different counterions. Dumbbell‐shaped rutile TiO2 and nanorod‐like rutile mesocrystals constructed from ultrathin nanowires, and quasi‐octahedral anatase TiO2 mesocrystals built from tiny nanoparticle subunits were achieved. Interestingly, the obtained anatase mesocrystals have a fine microporous structure and a large surface area. The influence of the counterions in the reaction system is discussed and possible mechanisms responsible for the formation of the unique ordered TiO2 superstructures with different morphologies and crystalline phases are also proposed based on a series of experimental results. The obtained TiO2 superstructures were used as anode materials in lithium ion batteries, and exhibited higher capacity and improved rate performance; this is attributed to the intrinsic characteristics of the mesoscopic TiO2 superstructures, which have a single‐crystal‐like and porous nature. 相似文献
3.
Dr. Hua Yu Jian Pan Yang Bai Dr. Xu Zong Prof. Xinyong Li Prof. Lianzhou Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13569-13574
One‐dimensional (1D) TiO2 nanostructures are desirable as photoanodes in dye‐sensitized solar cells (DSSCs) due to their superior electron‐transport capability. However, making use of the DSSC performance of 1D rutile TiO2 photoanodes remains challenging, mainly due to the small surface area and consequently low dye loading. Herein, a new type of photoanode with a three‐dimensional (3D) rutile‐nanorod‐based network structure directly grown on fluorine‐doped tin oxide (FTO) substrates was developed by using a facile two‐step hydrothermal process. The resultant photoanode possesses oriented rutile nanorod arrays for fast electron transport as the bottom layer and radially packed rutile head‐caps with an improved large surface area for efficient dye adsorption. The diffuse reflectance spectra showed that with the radially packed top layer, the light‐harvesting efficiency was increased due to an enhanced light‐scattering effect. A combination of electrochemical impedance spectroscopy (EIS), dark current, and open‐circuit voltage decay (OCVD) analyses confirmed that the electron‐recombiantion rate was reduced on formation of the nanorod‐based 3D network for fast electron transport. As a resut, a light‐to‐electricity conversion efficiency of 6.31 % was achieved with this photoanode in DSSCs, which is comparable to the best DSSC efficiencies that have been reported to date for 1D rutile TiO2. 相似文献
4.
Fluorine‐Doped Porous Single‐Crystal Rutile TiO2 Nanorods for Enhancing Photoelectrochemical Water Splitting
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Wen Qi Fang Dr. Ziyang Huo Dr. Porun Liu Xue Lu Wang Dr. Miao Zhang Dr. Yi Jia Dr. Haimin Zhang Prof. Huijun Zhao Prof. Hua Gui Yang Prof. Xiangdong Yao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11439-11444
Fluorine‐doped hierarchical porous single‐crystal rutile TiO2 nanorods have been synthesized through a silica template method, in which F? ions acts as both n‐type dopants and capping agents to make the isotropic growth of the nanorods. The combination of high crystallinity, abundant surface reactive sites, large porosity, and improved electronic conductivity leads to an excellent photoelectrochemical activity. The photoanode made of F‐doped porous single crystals displays a remarkably enhanced solar‐to‐hydrogen conversion efficiency (≈0.35 % at ?0.33 V vs. Ag/AgCl) under 100 mW cm?2 of AM=1.5 solar simulator illumination that is ten times of the pristine solid TiO2 single crystals. 相似文献
5.
二氧化钛多相催化是一种极具前途的环境污染深度净化技术。 本文以钛酸四丁酯和四氯化锡为原料,无水乙醇为溶剂,采用溶胶-凝胶法制备了掺杂二氧化锡的二氧化钛薄膜和复合氧化物粉体。通过测量薄膜的吸收光谱推算光学能隙,结果发现掺杂样品的光学能隙比纯二氧化钛样品有所变小。随着热处理温度的提高,掺杂和纯二氧化钛样品的光学能隙都略微降低。X-射线衍射分析表明,复合氧化物粉体的热处理温度对样品的晶体结构和光催化性能有重要影响。以掺杂二氧化锡5 % 摩尔比的样品与纯二氧化钛对照,500 ℃以下热处理样品以锐钛矿结构为主,600 ℃热处理样品为锐钛矿与金红石相共存,并显示了较好的光催化性能。透射电子显微镜观察显示,同样600 ℃热处理,掺杂样品要比纯二氧化钛具有更小的颗粒尺寸。在700 ℃热处理的样品中,掺杂样品只存在金红石相而纯二氧化钛样品中仍存有锐钛矿相。用阿伦尼乌斯经验关系式推测的晶粒生长的活化能,纯二氧化钛47.486 kJ.mol, 掺杂5 % 摩尔比的复合氧化物样品33.103 kJ.mol。以亚甲基蓝为降解物质,考察了掺杂量和热处理温度对样品的光催化性能。 相似文献
6.
Dr. Tao Tao Prof. Ying Chen Dan Zhou Dr. Hongzhou Zhang Dr. Sanly Liu Prof. Rose Amal Dr. Neeraj Sharma Dr. Alexey M. Glushenkov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):1091-1096
The mineral ilmenite is one of the most abundant ores in the Earth′s crust and it is the main source for the industrial production of bulk titanium oxide. At the same time, methods to convert ilmenite into nanostructures of TiO2 (which are required for new advanced applications, such as solar cells, batteries, and photocatalysts) have not been explored to any significant extent. Herein, we describe a simple and effective method for the preparation of rutile TiO2 nanorods from ball‐milled ilmenite. These nanorods have small dimensions (width: 5–20 nm, length: 50–100 nm, thickness: 2–5 nm) and possess large specific surface areas (up to 97 m2 g?1). Dissolution/hydrolysis/precipitation is proposed as a growth mechanism. The nanorods were found to have attractive photocatalytic properties in the degradation of oxalic acid. Their photocatalytic activity is close to that of the benchmark Degussa P25 material and better than that of a commercial high‐surface‐area rutile powder. 相似文献
7.
The Virtue of Defects: Stable Bromine Production by Catalytic Oxidation of Hydrogen Bromide on Titanium Oxide
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Maximilian Moser Dr. Izabela Czekaj Prof. Núria López Prof. Javier Pérez‐Ramírez 《Angewandte Chemie (International ed. in English)》2014,53(33):8628-8633
Rutile TiO2 is a heavily investigated oxide with, to date, scarce applications in industrial catalysis. The inactivity of this material in oxidations has been related to its inability to dissociate molecular oxygen. Herein we show how rutile catalyzes the oxidation of HBr to Br2 through defect states that are introduced during the reaction. The identification of active, stable, and abundant materials for bromine production is key to the future implementation of Br2‐mediated alkane functionalization processes. The catalytic properties of TiO2 are discussed in comparison to expensive rutile‐type oxides, such as RuO2 and IrO2, on the basis of surface characterization and molecular modeling. 相似文献
8.
Eunyoung Bae Naoya Murakami Teruhisa Ohno 《Journal of molecular catalysis. A, Chemical》2009,300(1-2):72-79
Size-, shape-, and phase structure-controlled synthesis of TiO2 nanocrystallites has long been one of the main themes in TiO2 research. Many synthetic techniques have been utilized in the preparation of TiO2 nanocrystals, among which hydrothermal treatment has been drawing much attention because it directly produces well-crystallized nanocrystallities of a wide range of compositions of crystal phases within a short reaction time. In this study, we carried out hydrothermal growth of rutile TiO2 rods by using aqueous titanium trichloride (TiCl3) solutions containing NaCl. Uniform ultrafine rutile TiO2 particles were obtained, and developed crystal faces were observed by TEM, SEM, XRD, and specific surface area measurements. The obtained rutile fine particles showed high levels of activity for degradation of 2-propanol and acetaldehyde under UV irradiation compared to the activity levels of anatase fine particles (ST-01) developed for environmental clean-up. The surface chemistry of the rutile TiO2 particles was also investigated. From photodeposition of Pt and PbO2, we suggest that the (1 1 0) face provides reductive sites and that the (1 1 1) face provides oxidative sites. These results indicate that the crystal faces facilitate the separation of electrons and holes, resulting in improvement of photocatalytic activity. 相似文献
9.
Photocatalytic Activity of TiO2 Nanofibers with Doped La Prepared by Electrospinning Method
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La‐TiO2 nanofibers are prepared by a sol‐gel assisted electrospinning method. The structure and morphology of La‐TiO2 nanofibers are characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that the weight percentage of anatase and rutile in the 1.5 mol% La‐TiO2 nanofibers calcined at 600 °C is about 8:2, which is similar to P‐25. The XRD data of La‐TiO2 nanofibers with different La content shows that La3+ dopant has a great inhibition on TiO2 phase transformation. The photocatalytic activity of the as‐prepared La‐TiO2 nanofibers is evaluated by photocatalytic decolorization of Methylene Blue (MB) aqueous solution. The results show that the 1.5 mol% La‐TiO2 nanofibers calcined at 600 °C exhibit high photocatalytic activity, indicating that 600 °C and 1.5 mol% are the appropriate calcination temperature and optimal molar ratio of La to Ti, respectively. 相似文献
10.
The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO2: Single‐Crystalline Ordered Mesoporous Nb‐TiO2 and Plate‐like Nb‐TiO2 with Ordered Mesoscale Dimples
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Takamichi Matsuno Dr. Yoshiyuki Kuroda Prof.Dr. Atsushi Shimojima Prof.Dr. Hiroaki Wada Prof.Dr. Kazuyuki Kuroda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13073-13079
Highly ordered mesoporous niobium‐doped TiO2 with a single‐crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb‐doped TiO2. The XPS measurements of Nb‐doped TiO2 showed the presence of Nb5+ and correspondingly Ti3+. With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate‐like TiO2 with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals. 相似文献
11.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(49):15756-15760
The M1 form of vanadium dioxide, which exhibits a reversible insulator–metal transition above room temperature, has been incorporated into nanoscale heterostructures through solution‐phase epitaxial growth on the tips of rutile TiO2 nanorods. Four distinct classes of VO2‐TiO2‐VO2 nanorod heterostructures are accessible by modulating the growth conditions. Each type of VO2‐TiO2‐VO2 nanostructure has a different insulator–metal transition temperature that depends on the VO2 domain sizes and the TiO2‐VO2 interfacial strain characteristics. 相似文献
12.
Fabrication of nanoporous polymeric crystalline TiO2 composite for photocatalytic degradation of aqueous organic pollutants under visible light irradiation
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A nanoporous polymeric crystalline TiO2 composite (TiO2/PDVB‐MA) has been successfully synthesized through an in situ synthesis method using divinylbenzene (DVB), methacrylic acid (MA) and tetrabutyl titanate. The experimental results showed that TiO2 nanoparticles composed of the mixture phases of anatase and rutile were homogeneously dispersed into the PDVB‐MA support. The TiO2/PDVB‐MA composite was used as photocatalyst for Rhodamine B (RhB), bisphenol A and 2,4,6‐trichlorophenol degradation under visible light irradiation. More interestingly, the excellent photocatalytic performance of the composite was observed with regard to RhB and bisphenol A, which might be ascribed to the synergistic effect between TiO2 nanoparticles and PDVB‐MA. Moreover, TiO2/PDVB‐MA composite could be recycled at least four times in the removal of RhB, suggesting that it is a promising photocatalyst to catalyze the degradation of organic pollutants under visible light irradiation. 相似文献
13.
Won Young Jung Seung Hee Baek Seong Soo Park Gun-Dae Lee Euh Duck Jeong Hyun Gyu Kim Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2007,91(2):233-240
The nanosized titania and TiO2/SiO2 particles were prepared by the microwave-hydrothermal method. The effect of physical properties TTIP/TEOS ratio and calcination
temperature has been investigated. The major phase of the pure TiO2 particle is of the anatase structure, and a rutile peak was observed above 800°C. In TiO2/SiO2 particles, however, no significant rutile phase was observed, although the calcination temperature was 900°C. No peaks for
the silica crystal phase were observed at either silica/titania ratio. The crystallite size of TiO2/SiO2 particles decreases as compared to pure TiO2 at high calcination temperatures. The TiO2/SiO2 particles show higher activity on the photocatalytic decomposition of orange II as compared to pure TiO2 particles. 相似文献
14.
Conducting polyaniline-rutile TiO2 nanocomposites for the development of high-k dielectric materials
Inorganic dielectrics encapsulated in an organic matrix are showing excellent promise as novel dielectric materials. In this work, firstly highly organized crystalline nanoparticles of rutile TiO2 were synthesized by acid hydrolysis of titanium isopropoxide at room temperature. Then we developed a novel dielectric material consisting of highly organized rutile TiO2/polyaniline (PAni) nanocomposites by in-situ chemical oxidative polymerization. The structural, morphological, conducting, and dielectric properties of the rutile TiO2/PAni nanoparticles have been evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution-transmission emission microscopy (HR-TEM), four-point probe technique, CV (Capacitance versus Voltage), and Impedance analyzer. The nanocomposites show 70 times higher permittivity compared to rutile nanoparticles and much higher compared to anatase/PAni (ES) nanocomposites at 10 MHz. Large interfacial polarizations, nanostructure, and dopant levels are the key factors for the large dielectric constant of the nanocomposites. The rutile/PAni (ES) nanocomposites might see potential uses in super-capacitors, gate dielectric in transistors, and capacitive-type gas sensors. 相似文献
15.
Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment
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Prof. Yusuke Ide Nozomu Inami Hideya Hattori Kanji Saito Dr. Minoru Sohmiya Prof. Nao Tsunoji Prof. Kenji Komaguchi Prof. Tsuneji Sano Prof. Yoshio Bando Prof. Dmitri Golberg Prof. Yoshiyuki Sugahara 《Angewandte Chemie (International ed. in English)》2016,55(11):3600-3605
Although tremendous effort has been directed to synthesizing advanced TiO2, it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase–rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2, which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2, inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective. 相似文献
16.
Here we report on the hierarchical porous rutile TiO2 nanorod micospheres as an anode material for lithium-ion batteries. The resulting hierarchical porous rutile TiO2 nanorod microspheres possessed much higher reversible capacity, cycling stability and rate capability than nanosized rutile TiO2 previously reported in the literatures. These good electrochemical performances may be attributed to the facile diffusion of Li+ ions from outside through the porous channels into the TiO2 nanorods in the microspheres and the high electrode–electrolyte contact area offered by hierarchical porous microspheres with a large specific surface area. 相似文献
17.
Density functional theory (DFT) and time‐dependent DFT calculations have been performed on a set of 34 titanium dioxide clusters ((TiO2)n with n ≤ 125) to investigate structural and electronic properties of nanostructured TiO2 (nano‐TiO2) materials. The investigated clusters include models of the three low‐energy polymorphic forms of TiO2 anatase, rutile, and brookite. A systematic comparison of clusters of increasing size show clear trends for emerging bulk properties in the investigated systems as the surface‐to‐bulk ratio changes from small clusters dominated by undercoordinated surface atoms to more realistic model nanocrystals with significant bulk components. Differences and similarities in terms of atomic coordination, structural stability, and electronic properties for the three different polymorphic forms of nano‐TiO2 are discussed. The calculations provide evidence for emerging polymorphism with increasing cluster sizes so that the different TiO2 forms can be clearly distinguished based on structural characteristics associated with the local bonding environment of the constituent atoms. © 2013 Wiley Periodicals, Inc. 相似文献
18.
Active Sites for Adsorption and Reaction of Molecules on Rutile TiO2(110) and Anatase TiO2(001) Surfaces (cited: 1)
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The reactivity of specific sites on rutile TiO2(110)-(1×1) surface and anatase TiO2(001)-(1×4) surface has been comparably studied by means of high resolution scanning tunneling microscopy. At the rutile TiO2(110)-(1×1) surface, we find the defects of oxygen vacancy provide distinct reactivity for O2 and CO2 adsorption, while the terminal fivefold-coordinated Ti sites dominate the photocatalytic reactivity for H2O and CH3OH dissociation. At the anatase TiO2(001)-(1×4) surface, the sixfold-coordinated terminal Ti sites at the oxidized surface seem to be inert in both O2 and H2O reactions, but the Ti-rich defects which introduce the Ti3+ state into the reduced surface are found to provide high reactivity for the reactions of O2 and H2O. By comparing the reactions on both rutile and anatase surfaces under similar experimental conditions, we find the reactivity of anatase TiO2(001) is actually lower than rutile TiO2(110), which challenges the conventional knowledge that the anatase (001) is the most reactive TiO2 surface. Our findings could provide atomic level insights into the mechanisms of TiO2 based catalytic and photocatalytic chemical reactions. 相似文献
19.
《Arabian Journal of Chemistry》2020,13(10):7453-7458
We present a simple and systematic synthesis method of Zn doped TiO2 (Zn/TiO2) that is usually prepared with sophisticated preparation procedures. Zn/TiO2 have been synthesized following a facile and efficient incipient wet impregnation method. The resulting Zn/TiO2 has been characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, which revealed the successful formation of the anatase phase and traces of the rutile phase. The existence of the rutile phase in smaller proportion was a clear sign of the Zn doping induced anatase-to-rutile phase transition. Sensible enhancement in the dielectric constant due to Zn addition has also been observed from experiment and approximate first-principle calculation. Thus, our results have significant impact on TiO2 based semiconductor technology. 相似文献
20.
Rezan Erdogan Mehmet Ferdi Fellah Isik Onal 《International journal of quantum chemistry》2011,111(1):174-181
Density functional theory (DFT) calculations performed at ONIOM DFT B3LYP/6‐31G**‐MD/UFF level are employed to study molecular and dissociative water adsorption on rutile TiO2 (110) surface represented by partially relaxed Ti25O37 ONIOM cluster. DFT calculations indicate that dissociative water adsorption is not favorable because of high activation barrier (23.2 kcal/mol). The adsorption energy and vibration frequency of both molecularly and dissociatively adsorbed water molecule on rutile TiO2 (110) surface compare well with the values reported in the literature. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献