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1.
Nanoscale ; 2020 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-32618325

RESUMO

Layered metal sulphides are promising anode materials for sodium-ion batteries (SIBs) and capacitors owing to their distinctive crystal structures and large interlayer spacings, which are suitable for Na+ insertion/extraction. However, low electronic conductivity, sluggish ion transfer and large volume variation of metal sulphides during sodiation/desodiation processes have hindered their practical application. In this work, we report the construction of a walnut-like core-shell MoS2@SnS heterostructure composite as an anode for SIBs with high capacity, remarkable rate and superior cycling stability. Experimental observations and first-principles density functional theory (DFT) calculations reveal that the enhanced electrochemical performances can be mainly ascribed to the boosted charge transfer and ion diffusion capabilities at the heterostructure interface driven by a self-building internal electric field. Our findings herein may pave the way for the development of novel heterostructure composite materials for beyond lithium-ion batteries and capacitors.

2.
Nanoscale ; 11(14): 6970-6981, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30916057

RESUMO

The lithium-selenium (Li-Se) battery has attracted growing interest recently due to its high energy density and theoretical capacity. However, the shuttle effect and volume change during cycling severely hinder its further application. In this work, we report a metal-organic framework (MOF)-derived nitrogen-doped core-shell hierarchical porous carbon (N-CSHPC) with interconnected meso/micropores to effectively confine Se for high-performance Li-Se batteries. The micropores were located at the ZIF-8-derived core and the ZIF-67-derived shell, while mesopores appeared at the core-shell interface after the pyrolysis of the core-shell ZIF-8@ZIF-67 precursor. Such a special hierarchical porous structure effectively confined selenium and polyselenides to prevent their dissolution from the pores and also alleviated the volume change. In particular, in situ nitrogen doping, which afforded N-CSHPC, not only improved the electrical conductivity of Se but also provided strong chemical adsorption on Li2Se, as confirmed by density functional theory calculations. On the basis of dual-physical confinement and strong chemisorption, Se/N-CSHPC-II (molar ratio of Co source to Zn source of 1.0 in the core-shell ZIF-8@ZIF-67 precursor) exhibited reversible capacities of up to 555 mA h g-1 after 150 cycles at 0.2 C and 462 mA h g-1 after 200 cycles at 0.5 C and even a discharge capacity of 432 mA h g-1 after 200 cycles at 1 C. Our demonstration here suggests that the carefully designed Se/C composite can improve the reversible capacity and cycling stability of Se cathodes for Li-Se batteries.

3.
Chem Commun (Camb) ; 54(86): 12250-12253, 2018 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-30318529

RESUMO

A porous TiO2/BaTiO3 heterostructure composite has been developed as a polysulfide mediator for lithium-sulfur batteries. Superior electrochemical performance has been achieved, mainly attributed to the synergy of TiO2 and BaTiO3 with dual affinity to polysulfides from chemical and ferroelectric-induced polarization effects, and enhanced redox kinetics propelled by the TiO2/BaTiO3 heterojunctions.

4.
Front Chem ; 6: 428, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30320061

RESUMO

CuO is a promising anode material for lithium-ion batteries due to its high theoretical capacity, low cost, and non-toxicity. However, its practical application has been plagued by low conductivity and poor cyclability. Herein, we report the facile synthesis of porous defective CuO nanosheets by a simple wet-chemical route paired with controlled annealing. The sample obtained after mild heat treatment (300°C) exhibits an improved crystallinity with low dislocation density and preserved porous structure, manifesting superior Li-ion storage capability with high capacity (~500 mAh/g at 0.2 C), excellent rate (175 mAh/g at 2 C), and cyclability (258 mAh/g after 500 cycles at 0.5 C). The enhanced electrochemical performance can be ascribed to the synergy of porous nanosheet morphology and improved crystallinity: (1) porous morphology endows the material a large contact interface for electrolyte impregnation, enriched active sites for Li-ion uptake/release, more room for accommodation of repeated volume variation during lithiation/de-lithiation. (2) the improved crystallinity with reduced edge dislocations can boost the electrical conduction, reducing polarization during charge/discharge. The proposed strategy based on synergic pore and defect engineering can pave the way for development of advanced metal oxides-based electrodes for (beyond) Li-ion batteries.

5.
Nanoscale ; 10(33): 15505-15512, 2018 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-30090890

RESUMO

Despite their high-energy density, low cost and environmental friendliness, the commercial application of lithium-sulfur batteries (LSBs) has been plagued by their severe capacity decay during long-term cycling caused by polysulfide shuttling. Herein, we demonstrate a synergetic vacancy and heterostructure engineering strategy using a nitrogen-doped graphene/SnS2/TiO2 (denoted as NG/SnS2/TiO2) nanocomposite to enhance the electrochemical performance of LSBs. It is noted that plentiful sulfur vacancy (Vs) defects and nanosized heterojunctions are created on the NG/SnS2/TiO2 composite as proved using electron paramagnetic resonance, transmission electron microscopy and X-ray photoelectron spectroscopy, which can serve as strong adsorption and activation sites for polar polysulfide intermediates, prevent their dissolution/shuttling, and accelerate their redox reaction. The novel NG/SnS2/TiO2-S cathode delivers a high initial capacity of 1064 mA h g-1 at 0.5 C and a high capacity retention rate of 68% after 500 cycles at 0.5 C.

6.
ACS Appl Mater Interfaces ; 9(50): 43665-43673, 2017 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-29192754

RESUMO

Vanadium oxides are promising anode materials for lithium-ion batteries (LIBs) due to their high capacity, good safety, and low cost. However, their practical application has been deferred by the poor rate capability and cycling stability. In this work, we report the designed synthesis of porous V2O3/VO2@carbon heterostructure electrode for high-performance LIBs. The synergic effects of porous nanostructures, phase hybridization with self-building electric field at heterointerface, and conductive carbon implantation effectively enhance the electronic/ionic conduction and buffer the volume variation in the composite material. Electrochemical tests reveal that the composite electrode exhibits high Li-ion storage capacities of 503 and 453 mAh/g at 100 and 500 mA/g, as well as good cycling stability with a retained capacity of 569 mAh/g over 105 cycles at 100 mA/g. In-depth kinetics analysis discloses that pseudocapacitive Li-ion storage process dominates in the composite electrode, which is probably enabled by efficient coupling of the heterostructure components. The strategy of in situ carbon implantation and phase hybridization presented herein may be extended to other electrode materials for rechargeable batteries with superior electrochemical properties.

7.
Chem Commun (Camb) ; 53(77): 10723-10726, 2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28914945

RESUMO

A carbon-free MoO2 nanosheet with amorphous/crystalline hybrid domain was synthesized, and demonstrated to be an efficient host material for lithium-ion capacitors. Discrepant crystallinity in MoO2 shows unique boundaries, which can improve Li-ion diffusion through the electrode. Improved rate capacities and cycling stability open the door to design of high-performance lithium ion capacitor bridging batteries and supercapacitors.

8.
ACS Appl Mater Interfaces ; 9(12): 10652-10663, 2017 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-28266839

RESUMO

TiO2 is a promising and safe anode material for lithium ion batteries (LIBs). However, its practical application has been plagued by its poor rate capability and cycling properties. Herein, we successfully demonstrate a novel structured TiO2 anode with excellent rate capability and ultralong cycle life. The TiO2 material reported here shows a walnut-like porous core/shell structure with hybridized anatase/amorphous phases. The effective synergy of the unique walnut-like porous core/shell structure, the phase hybridization with nanoscale coherent heterointerfaces, and the presence of minor carbon species endows the TiO2 material with superior lithium storage properties in terms of high capacity (∼177 mA h g-1 at 1 C, 1 C = 170 mA g-1), good rate capability (62 mA h g-1 at 100 C), and excellent cycling stability (∼83 mA h g-1 was retained over 10 000 cycles at 10 C with a capacity decay of 0.002% per cycle).

9.
Exp Mol Pathol ; 101(1): 150-6, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27460275

RESUMO

Genome-wide association study in diffusely infiltrating type cholangiocarcinoma (CC) can be limited due to the difficulty of obtaining tumor tissue. We aimed to evaluate the genomic alterations of diffusely infiltrating type CC using next-generation sequencing (NGS) of bile and to compare the variations with those of mass-forming type CC. A total of 24 bile samples obtained during endoscopic retrograde cholangiopancreatography (ERCP) and 17 surgically obtained tumor tissue samples were evaluated. Buffy coat and normal tissue samples were used as controls for a somatic mutation analysis. After extraction of genomic DNA, NGS analysis was performed for 48 cancer related genes. There were 27 men and 14 women with a mean age of 65.0±11.8years. The amount of extracted genomic DNA from 3cm(3) of bile was 66.0±84.7µg and revealed a high depth of sequencing coverage. All of the patients had genomic variations, with an average number of 19.4±2.8 and 22.3±3.3 alterations per patient from the bile and tumor tissue, respectively. After filtering process, damaging SNPs (8 sites for each type of CC) were predicted by analyzing tools, and their target genes showed relevant differences between the diffusely infiltrating and mass-forming type CC. Finally, in somatic mutation analysis, tumor-normal paired 14 tissue and 6 bile samples were analyzed, genomic alterations of EGFR, FGFR1, ABL1, PIK3CA, and CDKN2A gene were seen in the diffusely infiltrating type CC, and TP53, KRAS, APC, GNA11, ERBB4, ATM, SMAD4, BRAF, and IDH1 were altered in the mass-forming type CC group. STK11, GNAQ, RB1, KDR, and SMO genes were revealed in both groups. The NGS analysis was feasible with bile sample and diffusely infiltrating type CC revealed genetic differences compared with mass-forming type CC. Genome-wide association study could be performed using bile sample in the patients with CC undergoing ERCP and a different genetic approach for accurate diagnosis, pathogenesis study, and targeted therapy will be needed in diffusely infiltrating type CC.


Assuntos
Bile/metabolismo , Colangiocarcinoma/genética , Genes Neoplásicos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , DNA de Neoplasias/análise , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação/genética , Polimorfismo de Nucleotídeo Único/genética , Software
10.
Sci Rep ; 6: 25942, 2016 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-27181195

RESUMO

A highly crystalline three dimensional (3D) bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite constructed by nanoparticles in the range of 50~100 nm via a rapid microwave assisted solvothermal process followed by carbon coating have been synthesized as cathode material for high performance lithium-ion batteries. The abundant 3D macropores allow better penetration of electrolyte to promote Li(+) diffusion, the mesopores provide more electrochemical reaction sites and the carbon layers outside LiFePO4 nanoparticles increase the electrical conductivity, thus ultimately facilitating reverse reaction of Fe(3+) to Fe(2+) and alleviating electrode polarization. In addition, the particle size in nanoscale can provide short diffusion lengths for the Li(+) intercalation-deintercalation. As a result, the 3D macro-mesoporous nanosized LiFePO4/C electrode exhibits excellent rate capability (129.1 mA h/g at 2 C; 110.9 mA h/g at 10 C) and cycling stability (87.2% capacity retention at 2 C after 1000 cycles, 76.3% at 5 C after 500 cycles and 87.8% at 10 C after 500 cycles, respectively), which are much better than many reported LiFePO4/C structures. Our demonstration here offers the opportunity to develop nanoscaled hierarchically porous LiFePO4/C structures for high performance lithium-ion batteries through microwave assisted solvothermal method.

11.
Sci Rep ; 6: 20826, 2016 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-26860692

RESUMO

Development of three-dimensional nano-architectures on current collectors has emerged as an effective strategy for enhancing rate capability and cycling stability of the electrodes. Herein, a novel type of Ni3V2O8 nanowires, organized by ultrathin hierarchical nanosheets (less than 5 nm) on Ti foil, has been obtained by a two-step hydrothermal synthesis method. Studies on structural and thermal properties of the as-prepared Ni3V2O8 nanowire arrays are carried out and their morphology has changed obviously in the following heat treatment at 300 and 500 °C. As an electrode material for lithium ion batteries, the unique configuration of Ni3V2O8 nanowires presents enhanced capacitance, satisfying rate capability and good cycling stability. The reversible capacity of the as-prepared Ni3V2O8 nanowire arrays reaches 969.72 mAh · g(-1) with a coulombic efficiency over 99% at 500 mA · g(-1) after 500 cycles.

12.
Sci Rep ; 5: 11557, 2015 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-26170081

RESUMO

Hierarchically structured porous TiO2-B spheres have been synthesized via a hydrothermal process using amorphous titania/oleylamine composites as a self-sacrificing template. The TiO2-B spheres are constructed by interconnected nanotubes and possess a high specific surface area of 295 m(2) g(-1). When evaluated as an anode material in lithium-half cells, the as-obtained TiO2-B material exhibits high and reversible lithium storage capacity of 270 mA h g(-1) at 1 C (340 mA g(-1)), excellent rate capability of 221 mA h g(-1) at 10 C, and long cycle life with over 70% capacity retention after 1000 cycles at 10 C. The superior electrochemical performance of TiO2-B material strongly correlates to the synergetic superiorities with a combination of TiO2-B polymorph, hierarchically porous structure, interconnected nanotubes and spherical morphology. Post-mortem structural analyses reveal some discrete cubic LiTiO2 nanodots formed on the outer surfaces of TiO2-B nanotubes, which might account for the slight capacity loss upon prolonged electrochemical cycling.

13.
Nanoscale ; 7(30): 12979-89, 2015 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-26168989

RESUMO

A hierarchical nanosheet-constructed yolk-shell TiO2 (NYTiO2) porous microsphere is synthesized through a well-designed, one-pot, template-free solvothermal alcoholysis process using tetraethylenepentamine (TEPA) as the structure directing reagent. Such a yolk-shell structure with a highly porous shell and dense mesoporous core is quite advantageous as an anode material for lithium ion batteries (LIBs). The outer, 2D nanosheet-based porous (15 nm) shell and the nanocrystal-based inner mesoporous (3 nm) core provide a stable, porous framework, effective grain boundaries and a short diffusion pathway for Li(+) and electron transport, facilitating lithium insertion/extraction. The voids between the core and the shell can not only store the electrolyte due to capillary and facilitate charge transfer across the electrode/electrolyte interface but also buffer the volume change during the Li(+) insertion/extraction. As a result, NYTiO2 demonstrates excellent Li(+) capacity with outstanding cycle performance and superior rate capability at different rates for >700 cycles, retaining a 225 mA h g(-1) reversible capacity after 100 cycles at 1 C. In particular, the reversible capacity can still be maintained at 113 mA h g(-1) after 100 cycles at 10 C. We also observe the formation of homogeneously distributed 5-10 nm Li2Ti2O4 nanocrystallites on the surface of the nanosheets during the discharge-charge process. The synergy of the yolk-shell structure with dual mesopores in the shell and core and the Li2Ti2O4 nanocrystallites endow the hierarchical NYTiO2 with high reversible capacity, excellent rate capability and outstanding cycle performance.

14.
Nanoscale ; 7(9): 4163-70, 2015 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-25669161

RESUMO

Organolead halide perovskites are becoming intriguing materials applied in optoelectronics. In the present work, organolead iodide perovskite (OIP) nanowires (NWs) have been fabricated by a one step self-assembly method. The controllable NW distributions were implemented by a series of facile techniques: monolayer and small diameter NWs were prepared by precursor concentration tuning; NW patterning was achieved via selected area treatment assisted by a mask; NW alignment was implemented by modified evaporation-induced self-assembly (EISA). The synthesized multifunctional NWs were further applied in photodetectors (PDs) and solar cells as application demos. The PD performances have reached 1.32 AW(-1) for responsivity, 2.5 × 10(12) Jones for detectivity and 0.3 ms for response speed, superior to OIP films and other typical inorganic NW based PD performances. An energy conversion efficiency of ∼2.5% has been obtained for NW film based solar cells. The facile fabrication process, controllable distribution and optoelectronic applications make the OIP NWs promising building blocks for future optoelectronics, especially for low dimensional devices.

15.
Adv Sci (Weinh) ; 2(7): 1500070, 2015 07.
Artigo em Inglês | MEDLINE | ID: mdl-27708997

RESUMO

A hierarchical mesoporous TiO2 nanowire bundles (HM-TiO2-NB) superstructure with amorphous surface and straight nanochannels has been designed and synthesized through a templating method at a low temperature under acidic and wet conditions. The obtained HM-TiO2-NB superstructure demonstrates high reversible capacity, excellent cycling performance, and superior rate capability. Most importantly, a self-improving phenomenon of Li+ insertion capability based on two simultaneous effects, the crystallization of amorphous TiO2 and the formation of Li2Ti2O4 crystalline dots on the surface of TiO2 nanowires, has been clearly revealed through ex situ transmission electron microcopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) techniques during the Li+ insertion process. When discharged for 100 cycles at 1 C, the HM-TiO2-NB exhibits a reversible capacity of 174 mA h g-1. Even when the current density is increased to 50 C, a very stable and extraordinarily high reversible capacity of 96 mA h g-1 can be delivered after 50 cycles. Compared to the previously reported results, both the lithium storage capacity and rate capability of our pure TiO2 material without any additives are among the highest values reported. The advanced electrochemical performance of these HM-TiO2-NB superstructures is the result of the synergistic effect of hybriding of amorphous and crystalline (anatase/rutile) phases and hierarchically structuring of TiO2 nanowire bundles. Our material could be a very promising anodic material for lithium-ion batteries.

16.
Nanoscale ; 6(12): 6819-27, 2014 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-24828316

RESUMO

Well shaped single crystalline Mn3O4 nano-octahedra with exposed highly active {011} facets at different particle sizes have been synthesized and used as anode materials for lithium ion batteries. The electrochemical results show that the smallest sized Mn3O4 nano-octahedra show the best cycling performance with a high initial charge capacity of 907 mA h g(-1) and a 50th charge capacity of 500 mA h g(-1) at a current density of 50 mA g(-1) and the best rate capability with a charge capacity of 350 mA h g(-1) when cycled at 500 mA g(-1). In particular, the nano-octahedra samples demonstrate a much better electrochemical performance in comparison with irregular shaped Mn3O4 nanoparticles. The best electrochemical properties of the smallest Mn3O4 nano-octahedra are ascribed to the lower charge transfer resistance due to the exposed highly active {011} facets, which can facilitate the conversion reaction of Mn3O4 and Li owing to the alternating Mn and O atom layers, resulting in easy formation and decomposition of the amorphous Li2O and the multi-electron reaction. On the other hand, the best electrochemical properties of the smallest Mn3O4 nano-octahedra can also be attributed to the smallest size resulting in the highest specific surface area, which provides maximum contact with the electrolyte and facilitates the rapid Li-ion diffusion at the electrode/electrolyte interface and fast lithium-ion transportation within the particles. The synergy of the exposed {011} facets and the smallest size (and/or the highest surface area) led to the best performance for the Mn3O4 nano-octahedra. Furthermore, HRTEM observations verify the oxidation of MnO to Mn3O4 during the charging process and confirm that the Mn3O4 octahedral structure can still be partly maintained after 50 discharge-charge cycles. The high Li-ion storage capacity and excellent cycling performance suggest that Mn3O4 nano-octahedra with exposed highly active {011} facets could be excellent anode materials for high-performance lithium-ion batteries.

17.
J Colloid Interface Sci ; 418: 74-80, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-24461820

RESUMO

Hierarchical and porous V2O5 microspheres have been fabricated by a refluxing approach followed by annealing in air. The resulting porous V2O5 microspheres typically have diameters of 3-6 µm and are constructed of intertwined laminar nanocrystals or crosslinked nanobricks. It is found that the vanadyl glycolates rinsed with water have pronounced pore structures than that rinsed with ethanol alone. In addition, the configuration of the vanadyl glycolates microspheres can be tuned during the refluxing along with stirring. The possible formation processes of the vanadyl glycolates and V2O5 products have been discussed based on the experimental data. Electrochemical tests indicate that the hierarchical and porous V2O5 microspheres exhibit relatively high and stable Li(+) storage properties. The porous V2O5 microspheres assembled by intertwined nanoparticles maintain reversible Li(+) storage capacities of 102 and 80 mAh g(-1), respectively; whilst the porous V2O5 microspheres assembled by crosslinked nanobricks maintain reversible Li(+) storage capacities of 100 and 85 mAh g(-1) over 100 cycles at current rates of 0.5 and 1 C, respectively. The superior Li(+) storage performance of the hierarchical and porous V2O5 microspheres could mainly be ascribed to the improved electrode/electrolyte interface, reduced Li(+) diffusion paths, and relieved volume variation during lithiation and delithiation processes.

18.
J Colloid Interface Sci ; 417: 144-51, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24407670

RESUMO

Porous anatase TiO2 spheres have been synthesized by a microwave-assisted hydrothermal reaction of spherical particle precursors followed by annealing in air. The synthesized TiO2 spheres are formed by interconnected nanocrystals with size of 8.7 nm in average and have grain diameters of 250-400 nm. After annealing at 500°C, the TiO2 samples maintain spherical shape and develop highly mesoporous characteristics with a specific surface area of 151 m(2) g(-1). The TiO2 samples annealed at 750°C consist of larger aggregated particles with diameters of 500-900 nm and still retain mesoporous anatase structure, but with a reduced specific surface area of 25.6 m(2) g(-1). Electrochemical studies reveal that the porous TiO2 spheres annealed at 500°C own very high and stable lithium ion (Li(+)) storage capacities of 207, 184, 166, and 119 mA h g(-1) at 0.5, 1, 2, and 5C (850 mA g(-1)) rates, respectively, owing to their highly porous nanostructures and fine spherical morphology. In contrast, the TiO2 spheres annealed at 700°C exhibit modest electrochemical performance due to their reduced pore structures and larger crystallite size. The prepared porous TiO2 spherical particles show great promise for use as high performance anode materials for lithium ion batteries (LIBs).

19.
Nanoscale ; 5(14): 6338-43, 2013 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-23760208

RESUMO

Graphene-wrapped FeF3 nanocrystals (FeF3/G) have been successfully fabricated for the first time by a vapour-solid method, which can be generalized to synthesize other metal fluorides. The as-synthesized FeF3/G delivers a charge capacity of 155, 113, and 73 mA h g(-1) at 104, 502, and 1040 mA g(-1) in turn, displaying superior rate capability to bare FeF3. Moreover, it exhibits stable cyclability over 100 cycles with a charge capacity of 185.6 and 119.8 mA h g(-1) at 20.8 and 208 mA g(-1), respectively, which could be ascribed to the buffering effect and lowered resistance from the graphene. This versatile vapour-solid method and the improved cyclability provide a promising avenue for the application of metal fluorides as cathode materials.


Assuntos
Compostos Férricos/química , Fluoretos/química , Lítio/química , Fontes de Energia Elétrica , Técnicas Eletroquímicas , Eletrodos , Íons/química , Nanopartículas/química
20.
ACS Nano ; 6(3): 1970-8, 2012 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-22352710

RESUMO

We report tunable band gaps and transport properties of B-doped graphenes that were achieved via controllable doping through reaction with the ion atmosphere of trimethylboron decomposed by microwave plasma. Both electron energy loss spectroscopy and X-ray photoemission spectroscopy analyses of the graphene reacted with ion atmosphere showed that B atoms are substitutionally incorporated into graphenes without segregation of B domains. The B content was adjusted over a range of 0-13.85 atom % by controlling the ion reaction time, from which the doping effects on transport properties were quantitatively evaluated. Electrical measurements from graphene field-effect transistors show that the B-doped graphenes have a distinct p-type conductivity with a current on/off ratio higher than 10(2). Especially, the band gap of graphenes is tuned from 0 to ~0.54 eV with increasing B content, leading to a series of modulated transport properties. We believe the controllable doping for graphenes with predictable transport properties may pave a way for the development of graphene-based devices.

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