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Find video protocols related to scientific articles indexed in Pubmed.
High-performance supercapacitor electrode based on the unique ZnO@Co?O4? core/shell heterostructures on nickel foam.
ACS Appl Mater Interfaces
PUBLISHED: 09-09-2014
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Currently, tremendous attention has been paid to the rational design and synthesis of unique core/shell heterostructures for high-performance supercapacitors. In this work, the unique ZnO@Co3O4 core/shell heterostructures on nickel foam are successfully synthesized through a facile and cost-effective hydrothermal method combined with a short post annealing treatment. Mesoporous Co3O4 nanowires are multidirectional growing on the rhombus-like ZnO nanorods. In addition, the growth mechanism for such unique core/shell heterostructures is also proposed. Supercapacitor electrodes based on the ZnO@Co3O4 and Co3O4 heterostructures on nickel foam are thoroughly characterized. The ZnO@Co3O4 electrode exhibits high capacitance of 1.72 F cm(-2) (857.7 F g(-1)) at a current density of 1 A g(-1), which is higher than that of the Co3O4 electrode. Impressively, the capacitance of the ZnO@Co3O4 electrode increases gradually from 1.29 to 1.66 F cm(-2) (830.8 F g(-1)) after 6000 cycles at a high current density of 6 A g(-1), indicating good long-term cycling stability. These results indicate the unique ZnO@Co3O4 electrode would be a promising electrode for high-performance supercapacitor applications.
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High electrochemical performance based on the TiO2 nanobelt@few-layered MoS2 structure for lithium-ion batteries.
Nanoscale
PUBLISHED: 09-06-2014
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We report a facile approach to prepare MoS2 nanosheet coated TiO2 nanobelts. The TiO2@MoS2 structure exhibits a reversible capacity of 710 mA h g(-1) at 100 mA g(-1) after 100 cycles with highly stable capacity retention, and bears good rate capability with a reversible capacity of 417 mA h g(-1) at 1000 mA g(-1).
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Architectures of tavorite LiFe(PO4)(OH)(0.5)F(0.5) hierarchical microspheres and their lithium storage properties.
Nanoscale
PUBLISHED: 08-22-2014
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Tavorite LiFe(PO4)(OH)0.5F0.5 microspheres with different morphologies were prepared by a facile solvothermal route, and were further investigated as cathode materials for Li-ion batteries. We highly expect that this research can provide a useful fundamental understanding of the shape-dependent electrochemical performance of tavorite electrode materials.
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Enhanced sensitivity and stability of room-temperature NH? sensors using core-shell CeO? nanoparticles@cross-linked PANI with p-n heterojunctions.
ACS Appl Mater Interfaces
PUBLISHED: 07-31-2014
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We report a room-temperature NH3 gas sensor with high response and great long-term stability, including CeO2 NPs conformally coated by cross-linked PANI hydrogel. Such core-shell nanocomposites were prepared by in situ polymerization with different weight ratios of CeO2 NPs and aniline. At room temperature, the nanohybrids showed enhanced response (6.5 to 50 ppm of NH3), which could be attributed to p-n junctions formed by the intimate contact between these two materials. Moreover, the stability was discussed in terms of phytic acid working as a gelator, which helped the PANI sheath accommodate itself and enhance the mechanical strength and chemical stability of the sensors by avoiding "swelling effect" in high relative humidity. The sensors maintained its sensing characteristic (response of ca. 6.5 to 50 ppm of NH3) in 15 days. Herein, the obtained results could help to accelerate the development of ammonia gas sensor.
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High-performance humidity sensors from Ni(SO4)0.3(OH)1.4 nanobelts.
Nanoscale
PUBLISHED: 05-20-2014
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Ni(SO4)0.3(OH)1.4 nanobelts were synthesized by a facile hydrothermal method. Humidity sensors based on Ni(SO4)0.3(OH)1.4 nanobelts were fabricated and exhibited high sensitivity and a fast response. They also showed good long-term stability. The high performance could be related to the high surface-to-volume ratio of nanobelts and the chemical composition of Ni(SO4)0.3(OH)1.4.
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Strongly coupled hybrid nanostructures for selective hydrogen detection--understanding the role of noble metals in reducing cross-sensitivity.
Nanoscale
PUBLISHED: 03-25-2014
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Noble metal-semiconductor hybrid nanostructures can offer outperformance to gas sensors in terms of sensitivity and selectivity. In this work, a catalytically activated (CA) hydrogen sensor is realized based on strongly coupled Pt/Pd-WO3 hybrid nanostructures constructed by a galvanic replacement participated solvothermal procedure. The room-temperature operation and high selectivity distinguish this sensor from the traditional ones. It is capable of detecting dozens of parts per million (ppm) hydrogen in the presence of thousands of ppm methane gas. An insight into the role of noble metals in reducing cross-sensitivity is provided by comparing the sensing properties of this sensor with a traditional thermally activated (TA) one made from the same pristine WO3. Based on both experimental and density functional theory (DFT) calculation results, the cross-sensitivity of the TA sensor is found to have a strong dependence on the highest occupied molecular orbital (HOMO) level of the hydrocarbon molecules. The high selectivity of the CA sensor comes from the reduced impact of gas frontier orbitals on the charge transfer process by the nano-scaled metal-semiconductor (MS) interface. The methodology demonstrated in this work indicates that rational design of MS hybrid nanostructures can be a promising strategy for highly selective gas sensing applications.
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Three-dimensional Co?O?@NiMoO? core/shell nanowire arrays on Ni foam for electrochemical energy storage.
ACS Appl Mater Interfaces
PUBLISHED: 03-24-2014
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In this work, we report a facile two-step hydrothermal method to synthesize the unique three-dimensional Co3O4@NiMoO4 core/shell nanowire arrays (NWAs) on Ni foam for the first time. The Co3O4 nanowires are fully covered by ultrathin mesoporous NiMoO4 nanosheets. When evaluated as a binder-free electrode for supercapacitors in a 2 M KOH aqueous solution, the Co3O4@NiMoO4 hybrid electrode exhibits a greatly enhanced areal capacitance of 5.69 F cm(-2) at a high current density of 30 mA cm(-2), nearly 5 times that of the pristine Co3O4 electrode (1.10 F cm(-2)). The energy density of the hybrid electrode is 56.9 W h kg(-1) at a high power density of 5000 W kg(-1). In addition, the Co3O4@NiMoO4 hybrid electrode also exhibits good rate capability and cycling stability, which would hold great promise for electrochemical energy storage.
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Plate-like p-n heterogeneous NiO/WO? nanocomposites for high performance room temperature NO? sensors.
Nanoscale
PUBLISHED: 03-08-2014
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Plate-like heterogeneous NiO/WO? nanocomposites have been successfully prepared by annealing Ni(OH)? and H?WO? in air. These NiO/WO? nanocomposites have shown excellent sensitivity towards NO? and ultrafast response at room temperature due to their p-n heterogeneous characteristics.
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Surrounding sensitive electronic properties of Bi?Te? nanoplates-potential sensing applications of topological insulators.
Sci Rep
PUBLISHED: 01-30-2014
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Significant efforts have been paid to exploring the fundamental properties of topological insulators (TIs) in recent years. However, the investigation of TIs as functional materials for practical device applications is still quite limited. In this work, electronic sensors based on Bi2Te3 nanoplates were fabricated and the sensing performance was investigated. On exposure to different surrounding environments, significant changes in the conducting properties were observed by direct electrical measurements. These results suggest that nanostructured TIs hold great potential for sensing applications.
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High-Performance Lithium-Ion Battery Anode by Direct Growth of Hierarchical ZnCo2O4 Nanostructures on Current Collectors.
ACS Appl Mater Interfaces
PUBLISHED: 12-23-2013
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Hierarchical nanostructures that can be directly grown on a conducting substrate are a new trend in the design of active materials for high-performance lithium-ion batteries (LIBs). This article reports our design and fabrication of a 3D hierarchical ZnCo2O4 nanostructure (3D-ZCO-NS) directly grown on Ni foams. The goose-feather-like ZnCo2O4 bundled into a loose array structure with a large electrolyte contact area and good electrical and mechanical connection to the current collector. Electrochemical measurements confirmed the good performance of the electrode for reversible Li(+) storage (specific capacity of 932 mAh g(-1) in the 50th cycle at 1 A g(-1)) relative to a pasted electrode of 3D-ZCO-NSs (599 mAh g(-1) in the 50th cycle at 0.1 A g(-1)).
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Comparison of the Electrochemical Performance of NiMoO4 Nanorods and Hierarchical Nanospheres for Supercapacitor Applications.
ACS Appl Mater Interfaces
PUBLISHED: 12-09-2013
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Much attention has been paid to exploring electrode materials with enhanced supercapacitor performance as well as relatively low cost and environmental friendliness. In this work, NiMoO4 nanospheres and nanorods were synthesized by facile hydrothermal methods. The hierarchical NiMoO4 nanospheres were about 2.5 ?m in diameter and assembled from thin mesoporous nanosheets with a thickness of about 10-20 nm. The NiMoO4 nanorods were about 80 nm in diameter and about 300 nm to 1 ?m in length. Their electrochemical properties were investigated for use as electrode materials for supercapacitors (SCs). The NiMoO4 nanospheres exhibited a higher specific capacitance and better cycling stability and rate capability, which were attributed to their large surface area and high electrical conductivity. The specific capacitances were 974.4, 920.8, 875.5, 859.1, and 821.4 F/g at current densities of 1, 2, 4, 6, and 10 A/g, respectively. Remarkably, the energy density was able to reach 20.1 Wh/kg at a power density of 2100 W/kg. After 2000 cycles, the NiMoO4 nanospheres still displayed a high specific capacitance of about 631.8 F/g at a current density of 5 A/g. These results implied that the hierarchical NiMoO4 nanospheres could be a promising candidate for use as high-performance SCs.
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Targeting chemophotothermal therapy of hepatoma by gold nanorods/graphene oxide core/shell nanocomposites.
ACS Appl Mater Interfaces
PUBLISHED: 12-04-2013
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Nanographene oxide (NGO) are highly suitable to be the shells of inorganic nanomaterials to enhance their biocompatibility and hydrophilicity for biomedical applications while retaining their useful photonic, magnetic, or radiological functions. In this study, a novel nanostructure with gold nanorods (AuNRs) encapsulated in NGO shells is developed to be an ultraefficient chemophotothermal cancer therapy agent. The NGO shells decrease the toxicity of surfactant-coated AuNRs and provide anchor points for the conjugation of hyaluronic acid (HA). The HA-conjugated NGO-enwrapped AuNR nanocomposites (NGOHA-AuNRs) perform higher photothermal efficiency than AuNRs and have the capability of targeting hepatoma Huh-7 cells. NGOHA-AuNR is applied to load doxorubicin (DOX), and it exhibits pH-responsive and near-infrared light-triggered drug-release properties. Chemophotothermal combined therapy by NGOHA-AuNRs-DOX performs 1.5-fold and 4-fold higher targeting cell death rates than single chemotherapy and photothermal therapy, respectively, with biosafety to nontargeting cells simultaneously. Furthermore, our strategy could be extended to constructing other NGO-encapsulated functional nanomaterial-based carrier systems.
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CoO-carbon nanofiber networks prepared by electrospinning as binder-free anode materials for lithium-ion batteries with enhanced properties.
Nanoscale
PUBLISHED: 10-29-2013
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CoOx-carbon nanofiber networks were prepared from cobalt(ii) acetate and polyacrylonitrile by an electrospinning method followed by thermal treatment. The XPS results demonstrated that the cobalt compound in CoOx-carbon obtained at 650 °C was CoO rather than Co or Co3O4. The CoO nanoparticles with diameters of about 8 nm were homogeneously distributed in the matrix of the nanofibers with diameters of 200 nm. As binder-free anodes for lithium-ion batteries, the discharge capacities of such CoO-carbon (CoO-C) composite nanofiber networks increased with the pyrolysis and annealing temperature, and the highest value was 633 mA h g(-1) after 52 cycles at a current density of 0.1 A g(-1) when the CoO-C was obtained at 650 °C. In addition, the rate capacities of the CoO-C obtained at 650 °C were found to be higher than that of the sample annealed at a lower temperature and pure carbon nanofiber networks annealed at 650 °C. The improved properties of CoO-C nanofiber networks were ascribed to nanofibers as the framework to keep the structural stability, and favorable mass and charge transport. The present study may provide a new strategy for the synthesis of binder-free anodes for lithium-ion batteries with excellent properties.
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Hierarchical SnO2 Nanospheres: Bio-inspired Mineralization, Vulcanization, Oxidation Techniques, and the Application for NO Sensors.
Sci Rep
PUBLISHED: 09-25-2013
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Controllable synthesis and surface engineering of nanomaterials are of strategic importance for tailoring their properties. Here, we demonstrate that the synthesis and surface adjustment of highly stable hierarchical of SnO2 nanospheres can be realized by biomineralization, vulcanization and oxidation techniques. Furthermore, we reveal that the highly stable hierarchical SnO2 nanospheres ensure a remarkable sensitivity towards NO gas with fast response and recovery due to their high crystallinity and special structure. Such technique acquiring highly stable hierarchical SnO2 nanospheres offers promising potential for future practical applications in monitoring the emission from waste incinerators and combustion process of fossil fuels.
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High-performance supercapacitor and lithium-ion battery based on 3D hierarchical NH4F-induced nickel cobaltate nanosheet-nanowire cluster arrays as self-supported electrodes.
Nanoscale
PUBLISHED: 08-24-2013
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A facile hydrothermal method is developed for large-scale production of three-dimensional (3D) hierarchical porous nickel cobaltate nanowire cluster arrays derived from nanosheet arrays with robust adhesion on Ni foam. Based on the morphology evolution upon reaction time, a possible formation process is proposed. The role of NH4F in formation of the structure has also been investigated based on different NH4F amounts. This unique structure significantly enhances the electroactive surface areas of the NiCo2O4 arrays, leading to better interfacial/chemical distributions at the nanoscale, fast ion and electron transfer and good strain accommodation. Thus, when it is used for supercapacitor testing, a specific capacitance of 1069 F g(-1) at a very high current density of 100 A g(-1) was obtained. Even after more than 10,000 cycles at various large current densities, a capacitance of 2000 F g(-1) at 10 A g(-1) with 93.8% retention can be achieved. It also exhibits a high-power density (26.1 kW kg(-1)) at a discharge current density of 80 A g(-1). When used as an anode material for lithium-ion batteries (LIBs), it presents a high reversible capacity of 976 mA h g(-1) at a rate of 200 mA g(-1) with good cycling stability and rate capability. This array material is rarely used as an anode material. Our results show that this unique 3D hierarchical porous nickel cobaltite is promising for electrochemical energy applications.
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Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.
ACS Appl Mater Interfaces
PUBLISHED: 07-23-2013
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Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-?m structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors.
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Solvothermal synthesis of hollow urchin-like SnO2 nanospheres with superior lithium storage behavior.
J Nanosci Nanotechnol
PUBLISHED: 07-19-2013
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Hollow urchin-like SnO2 nanospheres with ultrathin nanorods have been successfully synthesized via a simple complex solvothermal route. The formation mechanism of the as-synthesized SnO2 nanospheres was simply explained. When tested as anode, the as-obtained hollow urchin-like SnO2 nanospheres exhibit excellent rate and cycling performances. It was expected that the as-synthesized SnO2 nanospheres could be applied as anode materials for future lithium-ion batteries.
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Ultrathin porous NiCo2O4 nanosheet arrays on flexible carbon fabric for high-performance supercapacitors.
ACS Appl Mater Interfaces
PUBLISHED: 07-12-2013
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NiCo2O4 with higher specific capacitance is an excellent pseudocapacitive material. However, the bulk NiCo2O4 material prevents the achievement of high energy desity and great rate performance due to the limited electroactive surface area. In this work, NiCo2O4 nanosheet arrays were deposited on flexible carbon fabric (CF) as a high-performance electrode for supercapacitors. The NiCo2O4 arrays were constructed by interconnected ultrathin nanosheets (10 nm) with many interparticle pores. The porous feature of NiCo2O4 nanosheets increases the amount of electroactive sites and facilitates the electrolyte penetration. Hence, the NiCo2O4/CF composites exhibited a high specific capacitance of 2658 F g(-1) (2 A g(-1)), good rate performance, and superior cycling life, suggesting the NiCo2O4/CF is a promising electrode material for flexible electrochemical capacitors.
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Carbon and graphene double protection strategy to improve the SnO(x) electrode performance anodes for lithium-ion batteries.
Nanoscale
PUBLISHED: 05-15-2013
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SnOx is a promising high-capacity anode material for lithium-ion batteries (LIBs), but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and release process. In this paper, SnOx carbon nanofibers (SnOx@CNFs) are firstly obtained in the form of a nonwoven mat by electrospinning followed by calcination in a 0.02 Mpa environment at 500 °C. Then we use a simple mixing method for the synthesis of SnOx@CNF@graphene (SnOx@C@G) nanocomposite. By this technique, the SnOx@CNFs can be homogeneously deposited in graphene nanosheets (GNSs). The highly scattered SnOx@C@G composite exhibits enhanced electrochemical performance as anode material for LIBs. The double protection strategy to improve the electrode performance through producing SnOx@C@G composites is versatile. In addition, the double protection strategy can be extended to the fabrication of various types of composites between metal oxides and graphene nanomaterials, possessing promising applications in catalysis, sensing, supercapacitors and fuel cells.
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Encapsulating gold nanoparticles or nanorods in graphene oxide shells as a novel gene vector.
ACS Appl Mater Interfaces
PUBLISHED: 03-21-2013
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Surface modification of inorganic nanoparticles (NPs) is extremely necessary for biomedical applications. However, the processes of conjugating ligands to NPs surface are complicated with low yield. In this study, a hydrophilic shell with excellent biocompatibility was successfully constructed on individual gold NPs or gold nanorods (NRs) by encapsulating NPs or NRs in graphene oxide (GO) nanosheets through electrostatic self-assembly. This versatile and facile approach remarkably decreased the cytotoxicity of gold NPs or NRs capping with surfactant cetyltrimethylammonium bromide (CTAB) and provided abundant functional groups on NPs surface for further linkage of polyethylenimine (PEI). The PEI-functionalized GO-encapsulating gold NPs (GOPEI-AuNPs) were applied to delivery DNA into HeLa cells as a novel gene vector. It exhibited high transfection efficiency of 65% while retaining 90% viability of HeLa cells. The efficiency was comparable to commercialized PEI 25 kDa with the cytotoxicity much less than PEI. Moreover, the results on transfection efficiency was higher than PEI-functionalized GO, which can be attributed to the small size of NPs/DNA complex (150 nm at the optimal w/w ratio) and the spherical structure facilitating the cellular uptake. Our work paves the way for future studies focusing on GO-encapsulating, NP-based nanovectors.
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Gram-scale synthesis of ultrasmall SnO2 nanocrystals with an excellent electrochemical performance.
Nanoscale
PUBLISHED: 03-13-2013
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The gram-scale synthesis of ultrasmall SnO2 nanocrystals has been successfully realized via a solvothermal process, during which the solvent used plays an important role in inhibiting the growth and aggregation of the nanocrystals. When investigating their electrochemical behaviour, the nanocrystal electrode shows an excellent performance in capacity retention and a better rate capacity.
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Electrospinning-thermal treatment synthesis: a general strategy to decorate highly porous nanotubes on both internal and external side-walls with metal oxide/noble metal nanoparticles.
Nanoscale
PUBLISHED: 02-28-2013
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The hybrid structure of nanoparticle-decorated highly porous nanotubes combines the advantages of large specific surface areas of nanoparticles and anisotropic properties of highly porous nanotubes, which is desirable for many applications, including batteries, photoelectrochemical water splitting, and catalysis. Here, we report a novel emulsion electrospinning-thermal treatment method to synthesize the nanoparticles deposited on both side walls of nanotubes with two unique characteristics: (1) large loading amount of nanoparticles per highly porous nanotubes (with the morphology of nanoparticles); (2) intimate contact between nanoparticles and highly porous nanotubes. Both features are advantageous for the above applications that involve both surface reactions and charge transportation processes. Moreover, the emulsion electrospinning-thermal treatment method is simple and straightforward, with which we have successfully decorated various highly porous metal oxide nanotubes with metal oxide or noble metal nanoparticles. The new method will have an impact on diverse technologies such as lithium ion batteries, catalysts, and photoelectrochemical devices.
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High-performance room-temperature hydrogen sensors based on combined effects of Pd decoration and Schottky barriers.
Nanoscale
PUBLISHED: 02-16-2013
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A new hydrogen sensor was fabricated by coating a Pd-decorated In2O3 film on Au electrodes. In response to 1 vol% H2 at room temperature, an ultra high sensitivity of 4.6 × 10(7) was achieved. But after an annealing treatment in vacuum, its sensitivity degenerated by 4 orders of magnitude. In addition, the response time and recovery time were also extended from 28 s and 32 s to 242 s and 108 s, respectively. It was found from contrast experiments that Pd decoration was essential to make the sensor work at room temperature and Schottky barriers played a vital role in enhancing the sensors performance. The methodology demonstrated in this paper shows that a combination of novel sensing materials and Schottky contact is an effective approach to design high-performance gas sensors.
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Indium-tin-oxide thin film transistor biosensors for label-free detection of avian influenza virus H5N1.
Anal. Chim. Acta
PUBLISHED: 02-12-2013
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As continuous outbreak of avian influenza (AI) has become a threat to human health, economic development and social stability, it is urgently necessary to detect the highly pathogenic avian influenza H5N1 virus quickly. In this study, we fabricated indium-tin-oxide thin-film transistors (ITO TFTs) on a glass substrate for the detecting of AI H5N1. The ITO TFT is fabricated by a one-shadow-mask process in which a channel layer can be simultaneously self-assembled between ITO source/drain electrodes during magnetron sputtering deposition. Monoclonal anti-H5N1 antibodies specific for AI H5N1 virus were covalently immobilized on the ITO channel by (3-glycidoxypropyl)trimethoxysilane. The introduction of target AI H5N1 virus affected the electronic properties of the ITO TFT, which caused a change in the resultant threshold voltage (VT) and field-effect mobility. The changes of ID-VG curves were consistent with an n-type field effect transistor behavior affected by nearby negatively charged AI H5N1 viruses. The transistor based sensor demonstrated high selectivity and stability for AI H5N1 virus sensing. The sensor showed linear response to AI H5N1 in the concentrations range from 5×10(-9) g mL(-1) to 5×10(-6) g mL(-1) with a detection limit of 0.8×10(-10) g mL(-1). Moreover, the ITO TFT biosensors can be repeatedly used through the washing processes. With its excellent electric properties and the potential for mass commercial production, ITO TFTs can be promising candidates for the development of label-free biosensors.
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Ternary Cu?SnS? cabbage-like nanostructures: large-scale synthesis and their application in Li-ion batteries with superior reversible capacity.
Nanoscale
PUBLISHED: 09-16-2011
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In this paper, novel ternary Cu(2)SnS(3) cabbage-like nanostructures are synthesized on a large scale via a facile solvothermal route. The individual Cu(2)SnS(3) cabbage-like hierarchitecture is constructed from 2D nanosheets with thickness of about 15.6 nm. The Cu(2)SnS(3) electrodes exhibit an initial reversible capacity of 842 mAh g(-1) and still reach 621 mAh g(-1) after 50 cycles. Such an admirable performance could be related to their 3D porous structural features as well as the high electrical conductivity induced by Cu. The electrochemical properties of the 3D hierarchical nanostructures imply its potential application in high energy density Li-ion batteries.
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Ionothermal synthesis of aggregated ?-Fe?O? nanoplates and their magnetic properties.
Nanoscale
PUBLISHED: 09-12-2011
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Aggregated ?-Fe(2)O(3) nanoplates have been successfully synthesized under ionothermal conditions through the self-assembly of nanoplatelets in a side-to-side manner. During the formation process of aggregated ?-Fe(2)O(3) nanoplates, pure ionic liquid media is essential for the assembly and coalescence of small nanoplatelets into final nanoplates. Moreover, the magnetic properties of the aggregated ?-Fe(2)O(3) nanoplates are strongly correlated to their unique structural characteristics.
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Bi2S3 nanomaterials: morphology manipulation and related properties.
Dalton Trans
PUBLISHED: 09-09-2011
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The Bi(2)S(3) nanomaterials with various morphologies such as nanorods, nanowires, nanowire bundles, urchin-like microspheres and urchin-like microspheres with cavities have been successfully synthesized through a simple hydrothermal method. Experimental results indicate that sulfur sources play crucial roles in determining the morphologies of Bi(2)S(3) products. Moreover, formation mechanisms of different Bi(2)S(3) nanostructures are discussed based on understanding of the growth habit of Bi(2)S(3) crystal. Finally, we also studied the morphologies-dependent electrochemical and optical properties of the as-synthesized Bi(2)S(3) nanomaterials.
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Facile solvothermal synthesis of mesoporous Cu?SnS? spheres and their application in lithium-ion batteries.
Nanoscale
PUBLISHED: 07-26-2011
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Three dimensional (3D) mesoporous Cu(2)SnS(3) spheres composed of nanoparticles were synthesized by a simple solvothermal route. As anode materials for lithium-ion batteries, they delivered remarkably enhanced cycling performances. This could be attributed to the 3D mesoporous structure which may be propitious to the accommodation of volume expansion. Besides, a possible electrochemical reaction mechanism was proposed based on cyclic voltammetry (CV) testing results and confirmed by subsequent ex situ XRD studies. In addition, the influence of testing temperature on cycling performance has also been investigated.
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Positive potential operation of a cathodic electrogenerated chemiluminescence immunosensor based on luminol and graphene for cancer biomarker detection.
Anal. Chem.
PUBLISHED: 04-22-2011
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In this work, we report a cathodic electrogenerated chemiluminescence (ECL) of luminol at a positive potential (ca. 0.05 V vs Ag/AgCl) with a strong light emission on the graphene-modified glass carbon electrode. The resulted graphene-modified electrode offers an excellent platform for high-performance biosensing applications. On the basis of the cathodic ECL signal of luminol on the graphene-modified electrode, an ECL sandwich immunosensor for sensitive detection of cancer biomarkers at low potential was developed with a multiple signal amplification strategy from functionalized graphene and gold nanorods multilabeled with glucose oxidase (GOx) and secondary antibody (Ab(2)). The functionalized graphene improved the electron transfer on the electrode interface and was employed to attach the primary antibody (Ab(1)) due to it large surface area. The gold nanorods were not only used as carriers of secondary antibody (Ab(2)) and GOx but also catalyzed the ECL reaction of luminol, which further amplified the ECL signal of luminol in the presence of glucose and oxygen. The as-proposed low-potential ECL immunosensor exhibited high sensitivity and specificity on the detection of prostate protein antigen (PSA), a biomarker of prostate cancer that was used as a model. A linear relationship between ECL signals and the concentrations of PSA was obtained in the range from 10 pg mL(-1) to 8 ng mL(-1). The detection limit of PSA was 8 pg mL(-1) (signal-to-noise ratio of 3). Moreover, the as-proposed low-potential ECL immunosensor exhibited excellent stability and reproducibility. The graphene-based ECL immunosensor accurately detected PSA concentration in 10 human serum samples from patients demonstrated by excellent correlations with standard chemiluminescence immunoassay. The results suggest that the as-proposed graphene ECL immunosensor will be promising in the point-of-care diagnostics application of clinical screening of cancer biomarkers.
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Highly sensitive electrogenerated chemiluminescence biosensor in profiling protein kinase activity and inhibition using gold nanoparticle as signal transduction probes.
Anal. Chem.
PUBLISHED: 10-26-2010
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A novel electrogenerated chemiluminescence (ECL) biosensor using gold nanoparticles as signal transduction probes was described for the detection of kinase activity. The gold nanoparticles were specifically conjugated to the thiophosphate group after the phosphorylation process in the presence of adenosine 59-[c-thio] triphosphate (ATP-s) cosubstrate. Due to its good conductivity, large surface area, and excellent electroactivity to luminol oxidization, the gold nanoparticles extremely amplified the ECL signal of luminol, offering a highly sensitive ECL biosensor for kinase activity detection. Protein kinase A (PKA), an important enzyme in regulation of glycogen, sugar, and lipid metabolism in the human body, was used as a model to confirm the proof-of-concept strategy. The as-proposed biosensor presented high sensitivity, low detection limit of 0.07 U mL(-1), wide linear range (from 0.07 to 32 U mL(-1)), and excellent stability. Moreover, this biosensor can also be used for quantitative analysis of kinase inhibition. On the basis of the inhibitor concentration dependent ECL signal, the half-maximal inhibition value IC(50) of ellagic acid, a PKA inhibitor, was estimated, which was in agreement with those characterized with the conventional kinase assay. While nearly no ECL signal change can be observed in the presence of Tyrphostin AG1478, a tyrosine kinase inhibitor, but not PKA inhibitor, shows its excellent performance in kinase inhibitor screening. The simple and sensitive biosensor is promising in developing a high-through assay of in vitro kinase activity and inhibitor screening for clinic diagnostic and drug development.
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A novel nonenzymatic hydrogen peroxide sensor based on MnO2/graphene oxide nanocomposite.
Talanta
PUBLISHED: 05-02-2010
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A new electrocatalyst, MnO(2)/graphene oxide hybrid nanostructure was successfully synthesized for the nonenzymatic detection of H(2)O(2). The morphological characterization was examined by scanning electron microscopy and transmission electron microscopy. The MnO(2)/graphene oxide based electrodes showed high electrochemical activity for the detection of H(2)O(2) in alkaline medium. The nonenzymatic biosensors displayed good performance along with low working potential, high sensitivity, low detection limit, and long-term stability, which could be attributed to the high surface area of graphene oxide providing for the deposition of MnO(2) nanoparticles. These results demonstrate that this new nanocomposite with the high surface area and electrocatalytic activity offers great promise for new class of nanostructured electrode for nonenzymatic biosensor and energy conversion applications.
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Synthesis of cobalt ion-based coordination polymer nanowires and their conversion into porous Co3O4 nanowires with good lithium storage properties.
Chemistry
PUBLISHED: 03-18-2010
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Cobalt ion-based coordination polymer nanowires were synthesized by using nitrilotriacetic acid (NA) as a chelating agent by a one-step hydrothermal approach. In the synthesis, cobalt ions were bonded with amino or carboxyl groups of NA to form one-dimension polymer nanowires, which can be confirmed by FTIR and TGA results. Our experimental results show that the morphologies of polymer nanowires greatly depend on the precursor salts, ratios between deionized water and isopropyl alcohol. The probable molecular formula and growth mechanism have been proposed. After heat treatment, the cobalt ion-based coordination polymer nanowires can be converted into porous Co(3)O(4) nanowires, which completely preserved the nanowire-like morphology. When used as anodes in lithium-ion batteries, the obtained porous Co(3)O(4) nanowires exhibited a high reversible capacity of 810 mA h g(-1) and stable cyclic retention at 30th cycle. The good electrochemical performance could be attributed to the porous nanostructure of Co(3)O(4), which provides pathways for easy accessibility of electrolytes and fast transportation of lithium ions.
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Electrografted poly(N-mercaptoethyl acrylamide) and Au nanoparticles-based organic/inorganic film: a platform for the high-performance electrochemical biosensors.
Chem Asian J
PUBLISHED: 02-11-2010
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In this study, we describe the use of the combination of eletrografting poly(N-mercaptoethyl acrylamide) and Au nanoparticles in the construction of high-performance biosensors. The poly(N-mercaptoethyl acrylamide) was electrografted onto the glassy carbon electrode surface, which provided a strongly adhering primer film for the stable attachment of Au nanoparticles and horseradish peroxidase (HRP) enzymes. The performances of the biosensors based on the HRP immobilized in the Au/poly(N-mercaptoethyl acrylamide) composite film were investigated. A couple of redox peaks were obtained, indicating that the Au nanoparticles could facilitate the direct-electron transfer between HRP and the underlying electrode. The biosensor showed an excellent electrocatalytic activity toward the reduction of hydrogen oxide and long-term stability, owing to the stable electrografted film and biocompatible Au nanoparticles. Our results demonstrate that the combination of electrografting and Au nanoparticles provides a promising platform for the immobilization of biomolecules and analysis of redox enzymes for their sensing applications.
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An excellent enzyme biosensor based on Sb-doped SnO2 nanowires.
Biosens Bioelectron
PUBLISHED: 01-29-2010
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Sb-doped SnO(2) nanowires were synthesized via thermal evaporation. Scanning electron microscopic, transmission electron microscopic, X-ray diffraction, current-voltage, and electrochemical impedance spectroscopy experiments have been used to characterize the structural and electrical behaviors of the nanowires. A mediator-free horseradish peroxidase-based H(2)O(2) biosensor was constructed through the Sb-doped SnO(2) nanowires used as the immobilization matrix for the enzymes. In comparison with the undoped SnO(2) nanowires, Sb-doped SnO(2) nanowires exhibited excellent electron transfer properties for the enzymes and higher electroactivity toward H(2)O(2). The biosensors displayed good performance along with high sensitivity, wide linear range, and long-term stability. Those can be attributed to the enhanced carrier density arising from Sb doping and biocompatible microenvironment provided by the Sb-doped SnO(2) nanowires. This study demonstrated that Sb-doped SnO(2) nanowires were promising platform for the construction of mediator-free biosensors and provided new further fundamental insights into the study of nanoscience and nanodevices.
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A novel non-enzymatic hydrogen peroxide sensor based on Mn-nitrilotriacetate acid (Mn-NTA) nanowires.
Talanta
PUBLISHED: 01-11-2010
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A novel non-enzymatic hydrogen peroxide sensor was realized from Mn-nitrilotriacetate acid (Mn-NTA) nanowires, which were successfully fabricated via a facile hydrothermal route. Cyclic voltammetry (CV) revealed that the Mn-NTA nanowires exhibited direct electrocatalytic activity for the oxidation of H(2)O(2) in phosphate buffer solution. The sensor showed linear response to H(2)O(2) at the concentrations range from 5 x 10(-6)M to 2.5 x 10(-3)M with a detection limit of 2 x 10(-7)M. The sensitivity was up to 78.9 microA mM(-1)cm(-2). These results indicated that the Mn-NTA nanowires were promising in realizing non-enzymatic H(2)O(2) detection.
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The large-scale synthesis of one-dimensional TiO2 nanostructures using palladium as catalyst at low temperature.
Nanotechnology
PUBLISHED: 01-12-2009
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The synthesis of TiO(2) nanostructures including nanowires and nanobelts has been demonstrated experimentally by anodization of Ti foil in an electrolyte, and by treatment in a PdCl(2) ethanol solution together with UV light irradiation and annealing at a temperature below 800 degrees C. The TiO(2) nanotube arrays resulting from the anodization were used as source precursor and transformed into nanowires and nanobelts respectively with high efficiency during the subsequent processes. The resulting TiO(2) nanowires and nanobelts, characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman and surface photovoltage (SPV) spectroscopy, are single rutile crystals of high quality. In addition to the synthesis of the nanostructure at low temperature, this method also shows great advantages for the selectable morphology of the final TiO(2) nanostructures via adjustment of the UV light irradiation time and annealing temperature.
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?-Fe2O3 nanochains: ammonium acetate-based ionothermal synthesis and ultrasensitive sensors for low-ppm-level H2S gas.
Nanoscale
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?-Fe(2)O(3) nanochains have been successfully synthesized via an ammonium acetate-based ionothermal synthetic route. When detecting low-ppm-level H(2)S gas, the nanochain sensor displayes high sensitivity due to its unique structure and smaller size.
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?-Cobalt sulfide nanoparticles decorated graphene composite electrodes for high capacity and power supercapacitors.
Nanoscale
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Electrochemical supercapacitors have drawn much attention because of their high power and reasonably high energy densities. However, their performances still do not reach the demand of energy storage. In this paper ?-cobalt sulfide nanoparticles were homogeneously distributed on a highly conductive graphene (CS-G) nanocomposite, which was confirmed by transmission electron microscopy analysis, and exhibit excellent electrochemical performances including extremely high values of specific capacitance (~1535 F g(-1)) at a current density of 2 A g(-1), high-power density (11.98 kW kg(-1)) at a discharge current density of 40 A g(-1) and excellent cyclic stability. The excellent electrochemical performances could be attributed to the graphene nanosheets (GNSs) which could maintain the mechanical integrity. Also the CS-G nanocomposite electrodes have high electrical conductivity. These results indicate that high electronic conductivity of graphene nanocomposite materials is crucial to achieving high power and energy density for supercapacitors.
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Facet-induced formation of hematite mesocrystals with improved lithium storage properties.
Chem. Commun. (Camb.)
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In this study, we prepared high-stability hematite mesocrystals by a facile route without polymer additives. In particular, the rhombic hematite mesocrystals exhibit excellent lithium insertion behavior compared to the hematite single-crystals.
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An evolution from 3D face-centered-cubic ZnSnO3 nanocubes to 2D orthorhombic ZnSnO3 nanosheets with excellent gas sensing performance.
Nanotechnology
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We have successfully observed the development of three-dimensional (3D) face-centered-cubic ZnSnO(3) into two-dimensional (2D) orthorhombic ZnSnO(3) nanosheets, which is the first observation of 2D ZnSnO(3) nanostructures to date. The synthesis from 3D to 2D nanostructures is realized by the dual-hydrolysis-assisted liquid precipitation reaction and subsequent hydrothermal treatment. The time-dependent morphology indicates the transformation via a dissolution-recrystallization mechanism, accompanied by a further growth process. Furthermore, the 2D ZnSnO(3) nanosheets consist of smaller sized nanoflakes. This further increases the special specific surface area and facilitates their application in gas sensing. The 2D ZnSnO(3) nanosheets exhibit excellent gas sensing properties, especially through their ultra-fast response and recovery. When exposed to ethanol and acetone, the response rate is as fast as 0.26 s and 0.18 s, respectively, and the concentration limit can reach as low as 50 ppb of ethanol. All these results are much better than those reported so far. Our experimental results indicate an efficient approach to realize high-performance gas sensors.
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Effects of Epstein-Barr virus infection on the development of multiple myeloma after liver transplantation.
Sci China Life Sci
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Reduced cellular immune function in patients after liver transplantation easily results in many types of viral infections, such as Epstein-Barr virus. Epstein-Barr virus is a ?-herpesvirus and is related to many malignant diseases, especially epithelial and lymph tumors. The abnormal interaction of cluster of differentiation 40 with cluster of differentiation 40 ligand and expression of cluster of differentiation 40 ligand are considered closely related to the development of myeloma cells. This study explored the influence and mechanism of Epstein-Barr virus infection on the phenotype and biological behavior of myeloma cells after liver transplantation. Flow cytometry was used to detect coexpression of cluster of differentiation 40 and cluster of differentiation 40 ligand in 10 samples of freshly isolated multiple myeloma cells. Cluster of differentiation 40 and cluster of differentiation 40 ligand were coexpressed in sample Nos. 5, 8, 9, and 10, particularly in sample No. 5. Western blot analysis was used to detect the expression of the Epstein-Barr virus antigens latent membrane protein 1 and Epstein-Barr virus nuclear antigen 2 in the multiple myeloma cell line RPMI 8226 infected with Epstein-Barr virus. The antigen expression indicated that Epstein-Barr virus can infect multiple myeloma virus cells in vitro. Reverse transcription-polymerase chain reaction revealed upregulated expression of cluster of differentiation 40 ligand on the infected RPMI 8226 cells, which may be involved in the anti-apoptosis activity of the infected cells. Confocal microscopy showed that pairs of molecules of cluster of differentiation 40, cluster of differentiation 40 ligand, and latent membrane protein 1 were colocalized on the surface of the infected cells. CXC chemokine receptor 4 was upregulated on the RPMI 8226 cells after Epstein-Barr virus infection. The migratory ability of the infected cells improved in the presence of the chemokine stromal cell-derived factor-1?. Anti-apoptosis and migration are known important biological characteristics of malignant cells. Our results indicate the involvement of Epstein-Barr virus in the origin and development of multiple myeloma. The risk of multiple myeloma increases when Epstein-Barr virus infects B cells in the germinal center, which may result in an anti-apoptosis effect of B cells and an improved ability to migrate from the germinal center to peripheral blood.
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Small quantities of cobalt deposited on tin oxide as anode material to improve performance of lithium-ion batteries.
Nanoscale
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In this report, we present a hybrid structure involving a small quantity of Co element uniformly deposited on porous SnO(2) spheres as stable and high capacity anode materials for lithium-ion batteries. Specifically, Co element deposited on SnO(2) nanomaterials exhibited an exceptional reversible capacity of 810 mA h g(-1) after 50 cycles which is higher than the pure SnO(2) electrode. Based on the experiments results, a possible mechanism for the change of this structure during lithium ion insertion/extraction was proposed. The minute quantity of Co element uniformly deposited on SnO(2) spherical structure could prevent Sn aggregation during charging-discharging, and high porosity of the spherical structure allowed the volume expansion during lithium ion alloying/dealloying. The SnO(2) deposited with small quantities of Co element as electrode facilitated improved performance of lithium ion batteries with higher energy densities.
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?-Fe2O3 nanowall arrays: hydrothermal preparation, growth mechanism and excellent rate performances for lithium ion batteries.
Nanoscale
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?-Fe(2)O(3) nanowall arrays (NWAs) were grown directly on Ni foam by a facile hydrothermal method. Based on time-dependent experiment results, a possible formation mechanism for this structure was proposed. The as-prepared ?-Fe(2)O(3) samples have an open network structure constituted of interconnected nanowalls and can be directly used as integrated electrodes for lithium-ion batteries (LIBs). The unique nanostructural feature is advantageous in electron transport and electrolyte diffusion efficiency, which can accelerate the electrochemical reaction. Thus, compared to a traditional electrode, the unique assembly reduces polarization of the electrode and results in excellent rate performances (440 mA h g(-1) at 5 C).
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