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1.
A templating method is developed to produce porous nanocrystalline anatase materials for negative electrodes in lithium‐ion batteries (LIBs). Amphiphilic diblock copolymers are used to generate template films with phase‐separated internal structure. Subsequent swelling with acidified titanium(IV) bis(ammonium lactato) dihydroxide (TALH) solution yielded structured hybrid films. Upon heating, the formation of TiO2 nanocrystals is induced, resulting in a three‐dimensional mesoporous structure directed by the bulk morphology of the polymer template. In comparison to commercial nanosized anatase, the structured anatase shows significant performance improvements in lithium‐ion coin cell batteries in terms of capacity, stability, and rate capability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1890–1896  相似文献   

2.
Ethylene polymerization was performed with the TiO2 nanotube supported metallocene catalytic system. The effects of Al/Zr molar ratio and time in polymerization on the catalytic behavior of the catalysts and the morphologies of the polyethylene were investigated. The nanofibers, floccules and nanosheets of polyethylene were obtained by controlling the polymerization conditions. Because the nanotubes confined the direction of propagation of the polyethylene chains, nanofibers were attained by extrusion polymerization, while the amount of floccules increased with extended polymerization time and nanosheets were mainly produced at high Al/Zr molar ratios. The possible correlation between the polymerization conditions and polyethylene morphologies was elucidated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.  相似文献   

3.
We report the optical absorption characteristics of highly porous, polycrystalline TiO2electrodes and the influence of hydrolysis period for the preparation processes by photoacoustic (PA) spectroscopy together with photoelectrochemical (PEC) current ones. The PA spectra show peaks which are attributed to the lowest transition energy due to the quantum confinement effect. The peak intensity decreases with the increase of hydrolysis periods, indicating the possibilities of the changes in the thermal properties and the densities due to hydrolysis processes. The PEC spectra indicate that the photocurrent intensity also show peak and that of the longer hydrolysis periods is somewhat smaller than others, indicating the increase of interface states due to the formation of grain boundaries with the increase of hydrolysis processes. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
Anatase TiO2 nanotube was doped with different contents of Sn (3, 5, and 7 at.%) through sol-gel method and subsequent hydrothermal process. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), and Hall effect measurement are utilized to characterize the structures, components, chemical environments, morphologies, specific areas, and electronic conductivities of the samples. The investigation in cycling performances demonstrates that 5 at.% Sn-doped TiO2 nanotube exhibits the best cycling stability, with specific capacity of 386 mAh g?1 and coulombic efficiency of 99.2 % after 50 cycles at 0.1 C, much higher than those of the other Sn-doped samples and pristine TiO2 nanotube. The improved electrochemical performances of Sn-doped TiO2 nanotube are attributed to the increase of electronic conductivity and therefore enhance the reversible capacity of the material.  相似文献   

5.
TiO2 nanotubes prepared by using a hydrothermal process were firstly coated with silver nanoparticles as the anode materials for lithium–ion batteries by the traditional silver mirror reaction. The physical properties of the as-synthesized samples were investigated by X-ray diffraction and transmission electron microscopic. The as-prepared samples were used as negative materials for lithium–ion battery, whose charge–discharge properties, cyclic voltammetry, electrochemical impedance spectroscopy and cycle performance were examined in detail. The results showed that the Ag additive decreased the polarization of anode, and marvelously improved the high-rate discharge capacity and cycling stability of TiO2 nanotubes.  相似文献   

6.
Self‐doped TiO2 nanotube array (DTNA) electrodes were fabricated through anodic oxidation combined with cathodic reduction. The morphology and structural features of pristine TiO2 nanotube arrays and DTNA electrodes were studied through scanning electron microscopy, X‐ray diffractometry, and X‐ray photoelectron spectroscopy. An accelerated life test was used to test the electrode service lifetime and thus the electrode's stability. The service lifetime of the DTNA electrode prepared at constant 40 V for 6 hr was approximately 338.7 hr at constant 1 mA/cm2 in a 1 M NaClO4 solution. Methyl orange (MO) was employed as the degradation probe for measuring electrochemical oxidation performance. The color removal rate of 200 mg/L MO of the DTNA electrode (85.2% at 1 mA/cm2) was greater than that of the Ti/IrO2 electrode (31.1% at 1 mA/cm2). The larger the surface area of the DTNA electrode is, the more conductive the electrode is for the degradation of organic substances. Organic degradation on the DTNA electrode occurred primarily through an indirect pathway (producing [?OH]).  相似文献   

7.
An ethanol solution of Ti-peroxy compounds was prepared from the ethanol solution of titanium isopropoxide (Ti(O-iPr)4) and H2O2. Heating of the ethanol solution of the Ti-peroxy compounds at 348 K formed a Ti-peroxy gel, and heat treatment of the gel at 348 K for more than 6 h formed gels that consisted of anatase nanoparticles. The diameter of the anatase nanoparticles increased from 9 to 15 nm as the heating time increased from 6 to 48 h. According to the results of the N2 adsorption measurement, the anatase nanoparticles had micropores, and the specific surface area (SBET) was in the range of 254 to 438 m2/g. The particle size, lattice strain, specific surface area, and photocatalytic activity of the anatase nanoparticles can be regulated by the heating time of the Ti-peroxy gel at 348 K.  相似文献   

8.
By using the surface photovoltage(SPV) technique based on a lock-in amplifier,surface states located 3.1 eV below the conduction band of TiO 2 have been detected in TiO 2 nanotube arrays prepared by anodization of titanium foil in fluoride-based ethylene glycol solution.The photo-induced charge transportation behavior of TiO 2 nanotube arrays was also studied by qualitatively analyzing their SPV phase spectra measured under different external bias.When a negative bias was applied,carriers excited from surface states have the same transportation properties as those excited from the valence band;in contrast,when a positive bias was applied,these two kinds of photo-excited carriers exhibit different transportation behavior.  相似文献   

9.
本文报道了水热法可控合成二氧化钛纳米晶及其在染料敏化太阳能电池中的应用.选择合适的有机碱胶化剂,能很好地控制二氧化钛纳米晶的生长,形成不同形貌和粒径的锐钛矿型二氧化钛纳米晶颗粒.染料敏化太阳能电池光电性能测试结果表明,以四乙基氢氧化铵为胶化剂合成的边长为8~13nm的正方形二氧化钛纳米晶构成的光阳极光电性能优于以四丁基氢氧化铵为胶化剂合成的边长为7~10nm的正方形二氧化钛纳米晶以及长18~35nm,宽10~18nm的长方形二氧化钛纳米晶构成的光阳极.用较高浓度的四甲基氢氧化铵胶化剂能合成球形或椭球形亚微米级二氧化钛颗粒,以其为散射中心在光阳极中构建散射层,染料敏化太阳能电池的光电转换效率能由6.77%提高到8.18%.  相似文献   

10.
A simple method for the controllable hydrothermal synthesis of nanocrystalline anatase TiO2(nc-TiO2) particles involving the selection of suitable organic alkali peptizing agents is reported.A dye-sensitized solar cell(DSSC) with square-like nc-TiO2 particles with side lengths about 8-13 nm-prepared using tetraethylammonium hydroxide(TEAOH)-in the photoelectrode showed higher photovoltaic performance than two other DSSCs with square-like nc-TiO2 particles with side lengths about 7-10 nm-prepared using tetrabutylammonium hydroxide-or elongated nc-TiO2 particles with lengths about 18-35 nm and width about 10 18 nm-prepared using tetramethylammonium hydroxide(TMAOH)-in the photoelectrodes.When a scattering layer prepared from sub-micron size spheres or cone-like nc-TiO2 particles-synthesized using a higher concentration of TMAOH-was added on top of the photoelectrode fabricated from nc-TiO2 synthesized with TEAOH,the energy conversion efficiency of the DSSC was markedly increased from 6.77% to 8.18%.  相似文献   

11.
通过半导体催化剂利用太阳能分解水制氢被认为是解决人类面临的环境问题和能源危机的有效途径.在众多的半导体光催化剂中,TiO2由于其良好的光化学稳定性、无毒性、丰富的形貌以及低廉的价格,在光催化制氢领域备受关注.然而TiO2的内在缺陷,如较宽的带隙、较窄的光响应范围,光生电子空穴对的快速复合,极大限制了其太阳能制氢效率.构建异质结结构被认为是解决以上问题的一个有效方法,通过将TiO2与另一个半导体复合可以提升催化剂对太阳光的吸收范围,也可降低光生电子空穴对的复合速率.但构建一个成功的异质结结构不仅要满足上述的要求,还需要保留异质结催化剂体系中光生电子和空穴的氧化还原能力.研究表明,S型异质结是将两个具有合适能带结构的半导体进行耦合,由于费米能级的差异,两个半导体间将发生电子转移,从而引起能带弯曲并形成内建电场.光照条件下,具有较弱还原能力的光生电子在内建电场和能带弯曲的作用下与较弱氧化能力的光生空穴复合,实现异质结催化剂体系中各个半导体内部光生载流子有效分离的目标,同时保留了异质结催化剂体系中较强氧化能力和较强还原能力的光生电子和空穴,进而实现光催化活性的提高.本文采用水热合成方法,将具有更强还原能力和可见光响应特性的半导体(ZnIn2S4)原位生长在TiO2纳米纤维表面,构建了1D/2DTiO2/ZnIn2S4S型异质结光催化剂.最优比例的TiO2/ZnIn2S4复合材料表现出优越的光催化制氢活性(6.03mmol/h/g),分别是纯TiO2和纯ZnIn2S4制氢活性的3.7倍和2倍.TiO2/ZnIn2S4复合材料光催化活性的提高可以归因于紧密的异质结界面、光生载流子的有效分离、丰富的反应活性位点以及增强的光吸收能力.通过原位XPS和DFT计算研究了异质结内部光生电子的转移机制.结果表明,在光照条件下电子由TiO2向ZnIn2S4迁移,遵循了S型异质结内部电子的转移机制,实现了TiO2和ZnIn2S4内部光生载流子的有效分离,同时保留了具有较强还原能力的ZnIn2S4价带电子和较强氧化能力的TiO2导带空穴,从而显著提升光催化制氢效率.综上,本文制备的TiO2/ZnIn2S4S型异质结光催化剂很好地克服了TiO2在光催化制氢领域所面临的诸多障碍,为设计和制备高效异质结光催化剂提供了新的思路.  相似文献   

12.
采用水热合成法以P25为原料制备了介孔TiO2纳米管, 并根据TEM和XPS表征结果对其形成机理进行了初步分析. 然后, 以制备出的介孔TiO2纳米管为载体, 钨酸铵为钨源, 采用传统浸渍方法制备了介孔WO3/TiO2纳米管催化剂. 利用N2吸附, TEM, XRD, XPS及Raman等手段对固载后的多相催化剂进行了表征, 并研究了催化剂在环戊烯选择氧化制备戊二醛反应中的催化性能. 结果表明, 在介孔20% WO3/TiO2纳米管催化下环戊烯的转化率达97.9%, 戊二醛的选择性高达69.3%. 钨物种以高度分散状态存在于催化剂中, 并与载体间存在着较强的相互作用, 使得钨的溶脱量很小, 脱落的钨对反应几乎没有影响. 另外, 催化剂具有较高的稳定性, 可以重复套用7次. 失活后的催化剂可通过简单焙烧的方式再生.  相似文献   

13.
The excellent photocatalytic hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 in the aqueous medium is still a big challenge. Herein, we report a facile one-pot evaporation-induced self-assembly (EISA) method to synthesize a series of CuO/TiO2 nanocomposites. The as-synthesized CuO/TiO2 photocatalysts exhibit remarkable catalytic activity under direct sunlight in selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) due to the synergistic interaction of guest copper nanoparticles with host titanium dioxide (TiO2) species. Especially, 5 wt% CuO/TiO2 nanocomposite revealed superior reaction rate constant (k) value (0.306 min−1) when compared to 3 wt% CuO/TiO2 (0.192 min−1) and 7 wt% CuO/TiO2 (0.240 min−1). Moreover, several characterization techniques (XRD, TEM, N2 adsorption–desorption isotherm, DRS, and XPS) were executed to deeply investigate the effect of copper content on the bulk and interfacial properties of the catalysts. The characterization results proved that the superior photocatalytic hydrogenation over 5 wt% CuO/TiO2 catalyst can be ascribed to moderate CuO loading as well as even dispersion of CuO species on the surface of active TiO2 host, which can largely improve the light absorption ability within visible light region. Besides, the 5 wt% CuO/TiO2 catalyst exhibits remarkable recyclability and durability, retaining its superior activity (above 95%) up to several repeating cycles, proving its practical applicability for hydrogenation reactions at domestic and industrial levels.  相似文献   

14.
Since the initial introduction of porous C2N-h2D materials by the Baek group in 2015, these materials have exhibited highly promising applications in fields such as semiconductor devices, heterogeneous catalysis, gas storage and separation, biomedicine, and more. However, much of the existing research on C2N materials has been based on theoretical calculations due to the challenges associated with their synthesis. In this study, an enhanced synthesis method for porous C2N materials has been successfully developed, involving the innovative and nonexplosive synthesis of hexaaminobenzene trihydrochloride (HAB·3HCl) as a crucial intermediate, as well as a time-efficient synthesis of C2N. Rigorous structural characterizations have been conducted, including solid-state NMR analysis, among others. The resultant C2N material has been effectively employed to improve the efficiency of CO2 conversion reactions. This straightforward protocol for synthesizing C2N materials is poised to stimulate further exploration and application of this promising 2D material in the near future.  相似文献   

15.
Self‐organized Ti/TiO2 nanotubular array electrodes were prepared by electrochemical anodization and used to monitor the reduction of the hair dye basic brown 17 (BB17) at a potential of ?0.60 V vs. Ag/AgCl. Analytical curves were obtained from 1.0×10?6 to 8.0×10?5 mol L?1 with a detection limit of 1.3×10?7 mol L?1 by using the best experimental conditions, linear scan voltammetry at pH 6, scan rate=60 mV s?1, and accumulation time=5 min. The detection system performance was not interfered by other hair dyes and successfully used to determine the dye in tap water samples.  相似文献   

16.
The potential to bias chemical reaction pathways is a significant goal for physicists and material researchers to design revolutionary materials. Recently, two‐dimensional materials have appeared as a promising candidate for exploring novel catalyst activity in organic reaction. In this context, herein we report an easy and efficient synthesis of substituted benzodiazepines in high yields through the graphene‐based mesoporous TiO2 nanocomposite (Gr@TiO2 NCs) catalyst. To validate the merits of the Gr@TiO2 NCs as a catalyst, we have also designed TiO2 nanoparticle (NPs) under similar conditions. Successful comprehension realization of Gr@TiO2 NCs and TiO2 NPs were concluded from the XRD, SEM, HR‐TEM, EDS elemental mapping, FT‐IR, Raman, UV–Vis and TGA analysis. Gr@TiO2 NCs has the propitious catalyst performance (~98%) over the TiO2 NPs (~77%), which could be scrutinized in terms of graphene support toward the TiO2 NPs and enable the large contact area between graphene and TiO2 NPs. Incorporated graphene maintaining TiO2 as a catalytically active and attracting electron to site isolation, as well as protecting TiO2 from oxidative degradation during the reaction. Moreover, the role of graphene is suggested to prolonged reaction duration, yield and unaltered throughout the reaction because of the π‐π interaction between graphene and TiO2 NPs. Additionally, the catalyst is recycled by filtration and reprocessed six times without having a significant loss in its catalytic activity.  相似文献   

17.
A novel Pt–TiO2/Ag nanotube photocatalyst has been synthesized successfully via a facile method. TiO2 nanotubes are assembled with numerous ultrathin TiO2 nanosheets and show a highly open structure. The gaps between adjacent TiO2 nanosheets can serve as channels for the access of reactants, accelerating the mass transfer process. During the fabrication process of the Pt–TiO2/Ag nanotube photocatalyst, high‐quality Pt–SiO2 nanotubes are synthesized first with the structure‐directing effect of polyvinylpyrrolidone. Then a TiO2 layer is coated on the outside surface of the silica nanotubes. The introduced titanium species can be converted into TiO2 nanosheet structure during the subsequent hydrothermal treatment, gradually constructing nanosheet‐assembled nanotubes. Lastly, after the introduction of another electron sink function site of Ag through UV irradiation, the Pt–TiO2/Ag nanotube photocatalyst with dual electron sink functional sites is obtained. The specially doped Pt and Ag NPs can simultaneously inhibit the recombination process of photogenerated charge carriers and increase light utilization efficiency. Therefore, the as‐synthesized Pt–TiO2/Ag nanotube catalyst exhibits a high photocatalytic degradation performance for rhodamine B of 0.2 min?1, which is about 3.2 and 5.3 times as high as that of Pt–TiO2 and TiO2 nanotubes because of the enhanced charge carrier separation efficiency. Furthermore, in the unique nanoarchitecture, the nanotubes are assembled with numerous ultrathin TiO2 nanosheets, which can absorb abundant active species and dye molecules for photocatalytic reaction. On the basis of experimental results, a possible rhodamine B degradation mechanism is proposed to explain the excellent photocatalytic efficiency of the Pt–TiO2/Ag nanotube photocatalyst.  相似文献   

18.
The threat and global concern of energy crises have significantly increased over the last two decades. Because solar light and water are abundant on earth, photocatalytic hydrogen evolution through water splitting has been considered as a promising route to produce green energy. Therefore, semiconductor photocatalysts play a key role in transforming sunlight and water to hydrogen energy. To date, various photocatalysts have been studied. Among them, TiO2 has been extensively investigated because of its non-toxicity, high chemical stability, controllable morphology, and high photocatalytic activity. In particular, 1D TiO2 nanofibers (NFs) have attracted increasing attention as effective photocatalysts because of their unique 1D electron transfer pathway, high adsorption capacity, and high photoinduced electron–hole pair transfer capability. However, TiO2 NFs are considered as an inefficient photocatalyst for the hydrogen evolution reaction (HER) because of their disadvantages such as a large band gap (~3.2 eV) and fast recombination of photoinduced electron–hole pairs. Therefore, the development of a high-performance TiO2 NF photocatalyst is required for efficient solar light conversion. In recent years, several strategies have been explored to improve the photocatalytic activity of TiO2 NFs, including coupling with narrow-bandgap semiconductors (such as ZnIn2S4). Recently, microwave (MW)-assisted synthesis has been considered as an important strategy for the preparation of photocatalyst semiconductors because of its low cost, environment-friendliness, simplicity, and high reaction rate. Herein, to overcome the above-mentioned limiting properties of TiO2 NFs, we report a 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction synthesized through a microwave (MW)-assisted process. Herein, the 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction was constructed rapidly by using in situ 2D ZnIn2S4nanosheets decorated on 1D TiO2 NFs. The loading of ZnIn2S4 nanoplates on the TiO2 NFs could be easily controlled by adjusting the molar ratios of ZnIn2S4 precursors to TiO2 NFs. The photocatalytic activity of the as-prepared samples for water splitting under simulated solar light irradiation was assessed. The experimental results showed that the photocatalytic performance of the ZnIn2S4/TiO2 composites was significantly improved, and the obtained ZnIn2S4/TiO2 composites showed increased optical absorption. Under optimal conditions, the highest HER rate of the ZT-0.5 (molar ratio of ZnIn2S4/TiO2= 0.5) sample was 8774 μmol·g-1·h-1, which is considerably higher than those of pure TiO2 NFs (3312 μmol·g-1·h-1) and ZnIn2S4nanoplates (3114 μmol·g-1·h-1) by factors of 2.7 and 2.8, respectively. Based on the experimental data and Mott-Schottky analysis, a possible mechanism for the formation of the S-scheme heterojunction between ZnIn2S4 and TiO2 was proposed to interpret the enhanced HER activity of the ZnIn2S4/TiO2heterojunctionphotocatalysts.   相似文献   

19.
基于光电化学测试考察了光电解池中电解质(NaNO3, NaCl, Na2SO4, Na2S和NaOH)的种类和浓度对阳极氧化法制备的锐钛矿型TiO2膜电极光电性能的影响, 并解释了其作用机理.结果表明, 电解质捕获空穴的能力顺序为Na2S>NaOH>Na2SO4>NaCl>NaNO3.Na2S和NaOH在溶液中具有协同作用, 当两者组成混合溶液并且浓度均为0.5 mol/L时, 更有利于TiO2膜光生电子-空穴对的分离和光电转化性能的提高.当0.5 mol/L NaCl溶液中的403不锈钢(403SS)与0.5 mol/L Na2S+0.5 mol/L NaOH混合溶液中的TiO2膜电极耦连时, 光照膜电极可使403SS的电极电位负移约650 mV, 具有良好的光生阴极保护效应.当切断光源时, 在该混合液中TiO2膜也能对403SS起到一定的阴极保护作用.  相似文献   

20.
Nanoscale anatase TiO2 single crystals were successfully synthesized using three kinds of activated carbon (AC) templates through a simple sol–gel method. The optimal photocatalyst (T‐WOAC) was obtained using wood‐based AC template. X‐ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller analyses revealed that T‐WOAC possessed a small crystallite size of 8.7 nm and a clear mesoporous structure. The photocatalytic properties of samples were then evaluated through photodegradation of crystal violet (CV). Results implied that the photocatalysts prepared using the AC templates exhibited superior photocatalytic activity to that of the original TiO2. This enhancement may be due to the small crystallite size, large specific surface area and pore volume of the catalysts prepared with ACs. T‐WOAC showed high photocatalytic activity, CV degradation of 99.01% after 120 min of irradiation and k = 0.03914 min?1, which is 3.9 times higher than that of the original TiO2 (k = 0.00994 min?1). This result can be mainly attributed to the application of WOAC with moderate specific surface area and pore volume to produce T‐WOAC. Alkaline conditions benefitted the photodegradation of CV over photocatalysts. This work proposes a possible degradation mechanism of CV and indicates that the fabricated photocatalysts can be used to effectively remove CV from aqueous solutions.  相似文献   

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