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1.
Hossein Yadegari Ali Jabbari Hossein Heli 《Journal of Solid State Electrochemistry》2012,16(1):227-234
Nanoparticles of lithium cobalt oxide (LiCoO2) and nanosheets of lithium vanadium oxide (LiV3O8) were synthesized by a citrate sol–gel combustion route. The physical characterizations of the electrodic materials were
carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also X-ray diffraction (XRD)
measurements. Near spherical nanoparticles of ≈100 nm and compact nanosheets with a few nanometers thick were observed by
SEM and TEM for LiCoO2 and LiV3O8, respectively. XRD data indicated that the as-prepared active materials presented pure phase of rhombohedral LiCoO2 with R-3m symmetry and monoclinic LiV3O8 with p21/m symmetry. The kinetics of electrochemical intercalation of lithium ion into the nanoparticles of LiCoO2 and nanosheets of LiV3O8 from 1.0 mol l−1 LiNO3 aqueous solution were investigated by cyclic voltammetry and chronoamperometry. An aqueous rechargeable lithium-ion battery
consisting of LiCoO2 nanoparticles as positive and LiV3O8 nanosheets as negative electrode was assembled. This battery represented a discharge voltage of about 1 V with good cycling
performance. 相似文献
2.
Template‐Free Synthesis of Core–Shell TiO2 Microspheres Covered with High‐Energy {116}‐Facet‐Exposed N‐Doped Nanosheets and Enhanced Photocatalytic Activity under Visible Light
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Dr. Qifeng Chen Dr. Baosheng Ren Dr. Yubao Zhao Xun Xu Prof. Heyi Ge Prof. Ruifang Guan Prof. Jincai Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17039-17046
Core–shell TiO2 microspheres possess a unique structure and interesting properties, and therefore, they have received much attention. The high‐energy facets of TiO2 also are being widely studied for the high photocatalytic activities they are associated with. However, the synthesis of the core–shell structure is difficult to achieve and requires multiple‐steps and/or is expensive. Hydrofluoric acid (HF), which is highly corrosive, is usually used in the controlling high‐energy facet production. Therefore, it is still a significant challenge to develop low‐temperature, template‐free, shape‐controlled, and relative green self‐assembly routes for the formation of core–shell‐structured TiO2 microspheres with high‐energy facets. Here, we report a template‐ and hydrofluoric acid free solvothermal self‐assembly approach to synthesize core–shell TiO2 microspheres covered with high‐energy {116}‐facet‐exposed nanosheets, an approach in which 1,4‐butanediamine plays a key role in the formation of nanosheets with exposed {116} facets and the doping of nitrogen in situ. In the structure, nanoparticle aggregates and nanosheets with {116} high‐energy facets exposed act as core and shell, respectively. The photocatalytic activity for degradation of 2,4,6‐tribromophenol and Rhodamine B under visible irradiation and UV/Vis irradiation has been examined, and improved photocatalytic activity under visible light owing to the hierarchical core–shell structure, {116}‐plane‐oriented nanosheets, in situ N doping, and large surface areas has been found. 相似文献
3.
This paper reports on the synthesis, characterization and electrochemical performance of LiV3O8 nanorods which were prepared through a very facile hydrothermal route. The diameters of the LiV3O8 nanorods are about 150 nm. The morphology of LiV3O8 can be controlled by adjusting the reaction conditions such as the reaction time and temperature. Electrochemical measurements reveal that the as‐prepared LiV3O8 nanorods display high initial discharge capacities (292.5 mA·hg?1) and excellent cyclability. This result indicates that the nanorods are a promising cathode candidate material for lithium batteries. 相似文献
4.
Low-dimensional Bi2Fe4O9 nanosheets and microrods have been selectively prepared by a solvothermal method, from which the growth of the Bi2Fe4O9 crystals can be controlled by the variation of reaction conditions. Structure determination showed that the nanosheets are mainly exposed by {001} facets while the microrods are exposed by {110} facets. Ab- sorption spectra revealed that there are two bandgaps observed for both nanosheets (at 1.9 and 1.55 eV) and microrods (1.7 and 1.45 eV), and they both would be available for the sunlight photocatalysis e ciently due to the intensive absorption ability in a wide region. Photocatalytic investigation demonstrated that the overall photocatalytic performance of the microrods is prior to that of the nanosheets due to the variation of bandgaps and exposed facets. The present report provides a useful alternative strategy for the controlling growth of nanostructures and/or microcrystals besides the present demonstration of the Bi2Fe4O9 crystals with diflerent bandgaps and facets that would be able to tune the corresponding photocatalytic ability selectively. 相似文献
5.
6.
Hierarchical MoS2 Shells Supported on Carbon Spheres for Highly Reversible Lithium Storage
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Dr. Lei Zhang Prof. Xiong Wen Lou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5219-5223
Hierarchical MoS2 shells supported on carbon spheres (denoted as C@MoS2) have been synthesized through a one‐step hydrothermal method. The obtained hierarchical C@MoS2 microspheres simultaneously integrate the structural and compositional design rationales for high‐energy electrode materials based on two‐dimensional (2D) nanosheets. When evaluated as an anode material for lithium‐ion batteries (LIBs), the hierarchical C@MoS2 microspheres manifest high specific capacity, enhanced cycling stability and good rate capability. 相似文献
7.
Yichen Hu Yuanhang Ren Gangfeng Tang Cheng Wang Min Tang Bin Yue Heyong He 《中国化学》2014,32(11):1151-1156
TiO2 nanosheets with dominant {001} facets, coupled with Cs2.5H0.5PW12O40, were successfully synthesized by a one‐step hydrothermal reaction. The photocatalytic activity of nanocatalysts was evaluated by the degradation of Rhodamine B under UV light irradiation. The results showed that both the addition of Cs2.5H0.5PW12O40 and the exposed {001} facets of TiO2 have a positive effect on the photocatalytic activity. The improved photoactivity of nanocomposites in comparison with that of TiO2 nanosheets could be attributed to the synergistic effect between Cs2.5H0.5PW12O40 and TiO2 which facilitates the separation of photo‐induced hole‐electron pairs. 相似文献
8.
A Microwave Synthesis of Mesoporous NiCo2O4 Nanosheets as Electrode Materials for Lithium‐Ion Batteries and Supercapacitors
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Anjon Kumar Mondal Dr. Dawei Su Shuangqiang Chen Katja Kretschmer Xiuqiang Xie Prof. Hyo‐Jun Ahn Prof. Guoxiu Wang 《Chemphyschem》2015,16(1):169-175
A facile microwave method was employed to synthesize NiCo2O4 nanosheets as electrode materials for lithium‐ion batteries and supercapacitors. The structure and morphology of the materials were characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller methods. Owing to the porous nanosheet structure, the NiCo2O4 electrodes exhibited a high reversible capacity of 891 mA h g?1 at a current density of 100 mA g?1, good rate capability and stable cycling performance. When used as electrode materials for supercapacitors, NiCo2O4 nanosheets demonstrated a specific capacitance of 400 F g?1 at a current density of 20 A g?1 and superior cycling stability over 5000 cycles. The excellent electrochemical performance could be ascribed to the thin porous structure of the nanosheets, which provides a high specific surface area to increase the electrode–electrolyte contact area and facilitate rapid ion transport. 相似文献
9.
《Electrochemistry communications》2007,9(8):1873-1876
Crystalline LiV3O8 and LiMn2O4 were prepared by conventional solid-state reaction and characterized by X-ray diffraction analysis. Cyclic voltammetry technique was employed to evaluate the electrochemical behaviors of LiV3O8 and LiMn2O4 in 2 mol/l Li2SO4 aqueous solution, and the results show that both LiV3O8 and LiMn2O4 are very stable in this aqueous electrolyte and can be used as the negative and positive electrode material without evident hydrogen or oxygen evolution. An aqueous rechargeable lithium battery (ARLB) was fabricated by using the above two intercalation compounds as the negative and positive electrodes. This battery exhibits good cycling behavior and the average discharge voltage is about 1.04 V. 相似文献
10.
Synthesis of {100} Facet Dominant Anatase TiO2 Nanobelts and the Origin of Facet‐Dependent Photoreactivity
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Dr. Feng Pan Prof. Kai Wu Prof. Hexing Li Prof. Guoqin Xu Prof. Wei Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15095-15101
Sword‐like anatase TiO2 nanobelts exposed with 78 % clean {100} facets were synthesized and the facet‐dependent photoreactivity of anatase TiO2 was investigated. By quantitative comparison with the reference {001} facets, the {100} facets possessed about ten‐times higher active sites density than that on {001} facets, resulting in higher photoreaction efficiency. After the active sites density normalization, the {100} and {001} facets exhibited distinct wavelength‐dependent photocatalytic performance, attributed to the anisotropic electronic structures in TiO2 crystals. 相似文献
11.
采用水热法制备了Al掺杂的锂二次电池正极材料LiV3-xAlxO8,并用X射线衍射和扫描电镜对材料的晶体结构和形貌进行了表征.以50 mA·g-1进行恒流充放电测试,结果表明Al掺杂能够明显改善材料的电化学性能.在掺杂改性的LiV3-xAlxO8材料中,LiV2.93Al0.07O8的初始容量最高,达到325 mAh·g-1.当掺杂量为x=0.04时,材料的循环性能最佳.LiV2.96Al0.04O8经20次循环后仍保持179 mAh·g-1的比容量,且充放电效率始终维持在98%左右. 相似文献
12.
In Situ Growth of Hierarchical SnO2 Nanosheet Arrays on 3D Macroporous Substrates as High‐Performance Electrodes
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Dr. Xinyu Zhao Dr. Bing Liu Prof. Changwen Hu Prof. Minhua Cao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):467-473
Finding out how to overcome the self‐aggregation of nanostructured electrode materials is a very important issue in lithium‐ion battery technology. Herein, by an in situ construction strategy, hierarchical SnO2 nanosheet architectures have been fabricated on a three‐dimensional macroporous substrate, and thus the aggregation of the SnO2 nanosheets was effectively prevented. The as‐prepared hierarchical SnO2 nanoarchitectures on the nickel foam can be directly used as an integrated anode for lithium‐ion batteries without the addition of other ancillary materials such as carbon black or binder. In view of their apparent advantages, such as high electroactive surface area, ultrathin sheet, robust mechanical strength, shorter ion and electron transport path, and the specific macroporous structure, the hierarchical SnO2 nanosheets exhibit excellent lithium‐storage performance. Our present growth approach offers a new technique for the design and synthesis of metal oxide hierarchical nanoarrays that are promising for electrochemical energy‐storage electrodes without carbon black and binder. 相似文献
13.
Controllable growth of anatase TiO2 crystals with exposed high reactive crystal facets has aroused great attention in the fields of science and technology due to their unique structure-dependent properties. Recently, much effort has been paid to synthesize anatase TiO2 crystals with exposed high reactive {001} facets. Herein, we review the recent progress in synthesizing {001} facets dominated anatase TiO2 crystals with different morphologies by various synthetic methods. Furthermore, our review is mainly focused on the formation/etching mechanisms of {001} facets dominated anatase TiO2 crystals based on our and other studies. The extensive application potentials of the anatase TiO2 crystals with exposed {001} facets have been summarized in this review such as photocatalysis, photoelectrocatalysis, solar energy conversion, lithium ion battery, and hydrogen generation. Based on the current studies, we give some perspectives on the research topic. We believe that this comprehensive review on anatase TiO2 crystals with high reactive {001} facets can further promote the relative research in this field. 相似文献
14.
Hierarchical Tubular Structures Composed of Co3O4 Hollow Nanoparticles and Carbon Nanotubes for Lithium Storage
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Dr. Yu Ming Chen Dr. Le Yu Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2016,55(20):5990-5993
Hierarchical tubular structures composed of Co3O4 hollow nanoparticles and carbon nanotubes (CNTs) have been synthesized by an efficient multi‐step route. Starting from polymer‐cobalt acetate (Co(Ac)2) composite nanofibers, uniform polymer‐Co(Ac)2@zeolitic imidazolate framework‐67 (ZIF‐67) core–shell nanofibers are first synthesized via partial phase transformation with 2‐methylimidazole in ethanol. After the selective dissolution of polymer‐Co(Ac)2 cores, the resulting ZIF‐67 tubular structures can be converted into hierarchical CNTs/Co‐carbon hybrids by annealing in Ar/H2 atmosphere. Finally, the hierarchical CNT/Co3O4 microtubes are obtained by a subsequent thermal treatment in air. Impressively, the as‐prepared nanocomposite delivers a high reversible capacity of 1281 mAh g?1 at 0.1 A g?1 with exceptional rate capability and long cycle life over 200 cycles as an anode material for lithium‐ion batteries. 相似文献
15.
Linlin Li Dr. Shengjie Peng Yanling Cheah Yahwen Ko Peifen Teh Grace Wee Dr. Chuiling Wong Prof. Madhavi Srinivasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14823-14830
Hierarchical CaCo2O4 nanofibers (denoted as CCO‐NFs) with a unique hierarchical structure have been prepared by a facile electrospinning method and subsequent calcination in air. The as‐prepared CCO‐NFs are composed of well‐defined ultrathin nanoplates that arrange themselves in an oriented manner to form one‐dimensional (1D) hierarchical structures. The controllable formation process and possible formation mechanism are also discussed. Moreover, as a demonstration of the functional properties of such hierarchical architecture, the 1D hierarchical CCO‐NFs were investigated as materials for lithium‐ion batteries (LIBs) anode; they not only delivers a high reversible capacity of 650 mAh g?1 at a current of 100 mA g?1 and with 99.6 % capacity retention over 60 cycles, but they also show excellent rate capability with respect to counterpart nanoplates‐in‐nanofibers and nanoplates. The high specific surface areas as well as the unique feature of hierarchical structures are probably responsible for the enhanced electrochemical performance. Considering their facile preparation and good lithium storage properties, 1D hierarchical CCO‐NFs will hold promise in practical LIBs. 相似文献
16.
Shanshan Qin Lancang Shui Benedict Osuagwu Nikita Denisov Dr. Alexander B. Tesler Prof. Patrik Schmuki 《ChemistryOpen》2022,11(3):e202200010
Titanium dioxide (TiO2) and, in particular, its anatase polymorph, is widely studied for photocatalytic H2 production. In the present work, we examine the importance of reactive facets of anatase crystallites on the photocatalytic H2 evolution from aqueous methanol solutions. For this, we synthesized anatase TiO2 nanocrystals with a large amount of either {001} facets, that is, nanosheets, or {101} facets, that is, octahedral nanocubes, and examined their photocatalytic H2 evolution and then repeated this procedure with samples where Pt co-catalyst is present on all facets. Octahedral nanocubes with abundant {101} facets produce >4 times more H2 than nanosheets enriched in {001} facets if the reaction is carried out under co-catalyst-free conditions. For samples that carry Pt co-catalyst on both {001} and {101} facets, faceting loses entirely its significance. This demonstrates that the beneficial role of faceting, namely the introduction of {101} facets that act as electron transfer mediator is relevant only for co-catalyst-free TiO2 surfaces. 相似文献
17.
Yongjun Li Dr. Xiaozhou Ye Shengxin Cao Chujing Yang Prof. Yun Wang Dr. Jianfeng Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3032-3041
The development of hierarchical TiO2 superstructures with new morphologies and intriguing photoelectric properties for utilizing solar energy is known to be an effective approach to alleviate the serious problems of environmental pollution. Herein, unique oxygen-deficient dumbbell-shaped anatase TiO2−x mesocrystals (DTMCs) enclosed by nearly 100 % {101} facets were readily synthesized by mesoscale transformation in TiCl3/acetic acid (HAc) mixed solution, followed by calcination under vacuum. These mesocrystals exhibited much higher photoreactivity toward removing the model pollutants methyl orange and CrVI than truncated tetragonal bipyramidal anatase nanocrystals (TNCs), anatase mesocrystals built from truncated tetragonal bipyramidal anatase nanocrystals (TTMCs), and anatase mesocrystals constructed by anatase nanocrystals with nearly 100 % exposed {101} facets (TMCs), revealing that both the oxidation and reduction abilities of anatase TiO2 were simultaneously enhanced upon fabricating an oxygen-deficient mesocrystalline architecture with about 100 % exposed {101} facets. Further characterization illustrated that such an enhancement of photoreactivity was mainly due to the strengthened light absorption, boosted charge carrier separation, and nearly 100 % exposed {101} facets of the oxygen-deficient dumbbell-shaped anatase mesocrystals. This work will be useful for guiding the synthesis of oxygen-deficient ordered superstructures of metal oxides with desired morphologies and exposed facets for promising applications in environmental remediation. 相似文献
18.
Xueliang Li Peipei Li Mei Luo Xiangying Chen Jiejie Chen 《Journal of Solid State Electrochemistry》2010,14(7):1325-1332
In this paper, we successfully developed a novel method to synthesize uniform carnation-like lithium vanadate nanostructures
by combining electrochemical deposition and solvo-hydrothermal method. The samples were characterized by field emission scanning
electron microscopy, power X-ray diffraction, and thermogravimetric analysis. The results show that the LiV3O8·H2O carnation-like nanostructure is 2–3 μm in diameter and assembled from nanosheets with thickness of 10–20 nm. Based on a
series of experiments, we proposed a possible growth mechanism, in which the supersaturation derived from electric field and
high conductivity under solvo-hydrothermal conditions due to the successive growth of lithium vanadate. In our work, we have
discussed three different solvo-hydrothermal systems. It is proved that the morphology of coating materials could be conveniently
controlled by selecting alcohols with different chain of alkyl. Compared with short-chain alcohol, CH3–(CH2)6–CH2–OH was beneficial to promote the oriented growth of nanosheets. Electrochemical performances of lithium vanadate cathode
materials were characterized by galvanostatic charge–discharge, and LiV3O8 synthesized in n-octanol aqueous solution exhibits the highest capacity of 357 mAh g−1 and best cycle stability. Furthermore, the influence of solvo-hydrothermal conditions on the morphology and electrochemical
performance of products has also been studied. 相似文献
19.
Wenwu Li Xianfu Wang Bin Liu Dr. Sijun Luo Zhe Liu Xiaojuan Hou Qingyi Xiang Prof. Di Chen Prof. Guozhen Shen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8650-8656
Aligned Ca2Ge7O16 nanowire arrays were successfully grown on carbon textiles to form hierarchical 3D structures by using a facile hydrothermal method on a large scale. Typical Ca2Ge7O16 nanowires are single crystals that show preferred growth along the [001] direction. The 3D hierarchical structures were used as binder‐free anodes for lithium‐ion batteries, which showed the features of highly reversible capacity (900–1100 mA h g?1 at a current density of 300 mA g?1), remarkable cycling stability, even over 100 cycles, and good rate capability, with a capacity of about 500 mA h g?1 at 3 A g?1. Furthermore, highly bendable full cells were also fabricated, which showed high flexibility, with little voltage change after bending 600 times, and superior temperature tolerance within the range 4–60 °C, thus demonstrating their promising potential for applications in high‐performance lithium‐ion batteries. 相似文献
20.
Ultrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be extended to further enhance their photocatalytic activity for H2 evolution. Herein, we present a successful attempt to selectively dope lanthanide ions into the {101} facets of ultrathin TiO2 nanosheets with coexposed {001}/{101} facets through a facile one-step solvothermal method. The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO2 nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra. Upon simulated sunlight irradiation, we observed a 4.2-fold enhancement in the photocatalytic H2 evolution activity of optimal Yb3+-doped TiO2 nanosheets compared to that of their undoped counterparts. Furthermore, when Pt nanoparticles were used as cocatalysts to reduce the H2 overpotential in this system, the photocatalytic activity enhancement factor increased to 8.5. By combining these results with those of control experiments, we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H2 evolution activity of lanthanide-doped TiO2 nanosheets with coexposed {001}/{101} facets. 相似文献