A5038819100- Graphene research and applications
- Carbon Nanotubes in Composites
- Fullerene Chemistry and Applications
- 2D Materials and Applications
- Boron and Carbon Nanomaterials Research
- MXene and MAX Phase Materials
- Advancements in Battery Materials
- Quantum and electron transport phenomena
- Molecular Junctions and Nanostructures
- Topological Materials and Phenomena
- Surface and Thin Film Phenomena
- Chemical and Physical Properties of Materials
- Perovskite Materials and Applications
- Diamond and Carbon-based Materials Research
- Advanced Chemical Physics Studies
- Mechanical and Optical Resonators
- Chalcogenide Semiconductor Thin Films
- Graphene and Nanomaterials Applications
- Nanowire Synthesis and Applications
- Synthesis and Properties of Aromatic Compounds
- Thermal properties of materials
- Nanotechnology research and applications
- Fiber-reinforced polymer composites
- Semiconductor materials and devices
- Graphite, nuclear technology, radiation studies
University of Tsukuba
2016-2025
Universidad de Sevilla
2023
Catholic University of Eichstätt-Ingolstadt
2023
The University of Tokyo
2008-2019
National Institute for Materials Science
2019
Tokyo University of Science
2019
Japan Science and Technology Agency
2007-2018
Ibaraki University
2018
National Institute of Advanced Industrial Science and Technology
2003-2010
Tokyo Institute of Technology
1995-2010
Two-dimensional (2D) materials are promising for applications in a wide range of fields because their unique properties. Hydrogen boride sheets, new 2D material recently predicted from theory, exhibit intriguing electronic and mechanical properties as well hydrogen storage capacity. Here, we report the experimental realization sheets with an empirical formula H1B1, produced by exfoliation complete ion-exchange between protons magnesium cations diboride (MgB2) average yield 42.3% at room...
Monolayers of transition metal dichalcogenides (TMDCs) have attracted a great interest for post-silicon electronics and photonics due to their high carrier mobility, tunable bandgap, atom-thick 2D structure. With the analogy conventional silicon electronics, establishing method convert TMDC p- n-type semiconductors is essential various device applications, such as complementary metal-oxide-semiconductor (CMOS) circuits photovoltaics. Here, successful control electrical polarity monolayer...
Tubular structures of transition metal dichalcogenides (TMDCs) have attracted attention in recent years due to their emergent physical properties, such as the giant bulk photovoltaic effect and chirality-dependent superconductivity. To understand control these it is highly desirable develop a sophisticated method fabricate TMDC tubular with smaller diameters more uniform crystalline orientation. For this purpose, rolling up monolayers into nanoscrolls an attractive approach fabricating...
We report total-energy electronic structure calculations that provide energetics of encapsulation C60 in the carbon nanotube and structures resulting peapods. find encapsulating process is exothermic for (10,10) nanotube, whereas processes are endothermic (8,8) (9,9) nanotubes, indicative minimum radius 6.4 A. also C(60)@(10,10) a metal with multicarriers each which distributes either along or on chain. This unusual feature due to nearly free electron state inherent hierarchical solids...
We report first-principles total-energy electronic-structure calculations in the density-functional theory performed for hexagonally bonded honeycomb sheets consisting of B, N, and C atoms. find that ground state BNC with particular stoichiometry is ferromagnetic. Detailed analyses energy bands spin densities unequivocally reveal nature ferromagnetic ordering, leading to an argument sheet a manifestation flat-band ferromagnetism.
We report the polarized optical absorption spectra of single-walled 4 A carbon nanotubes arrayed in channels an AlPO (4)-5 single crystal. When light electric field (E) is parallel to tube direction (c), display a sharp peak at 1.37 eV, with two broadbands 2.1 and 3.1 eV. In E perpendicular c configuration, nearly transparent measured energy region 0.5-4.1 The dipole selection rules are discussed, bands assigned transitions between Van Hove singularities. agreed well ab initio calculations...
First-principles total energy calculations are performed to investigate the energetics and electronic structures of graphene adsorbed on both an oxygen-terminated SiO2 (0001) surface a fully hydroxylated surface. We find that there several stable adsorption sites for O-terminated surfaces. The binding in most geometry is found be 15 meV per C atom, indicating weak interaction between also semiconductor irrespective arrangement due variation on-site induced by substrate.
Control over chemical reactivity is essential in the field of nanotechnology. Graphene a two-dimensional atomic sheet sp(2) hybridized carbon with exceptional properties that can be altered by functionalization. Here, we transferred single-layer graphene onto flexible substrate and investigated functionalization using different aryl diazonium molecules while applying mechanical strain. We found strain alter structure graphene, dramatically increase reaction rate, factor up to 10, as well...
Growing coaxial nanotubes Heterostructures of highly crystalline two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS 2 ) are now routinely assembled from films or grown layers. Xiang et al. report the growth one-dimensional analogs these heterostructures on single-walled carbon (SWCNTs) through a chemical vapor deposition (see Perspective by Gogotsi Yakobson). Single-crystalline monolayers multilayers hBN MoS were that maintained...
Here we report the thermal conversion of one-dimensional (1D) fullerene (C60) single-crystal nanorods and nanotubes to nanoporous carbon materials with retention initial 1D morphology. The C60 crystals are heated directly at very high temperature (up 2000 °C) in vacuum, yielding a new family carbons having π-electron conjugation within sp(2)-carbon robust frameworks. These show excellent electrochemical capacitance superior sensing properties for aromatic compounds compared commercial...
Band gap opening in bilayer graphene (BLG) under a vertical electric field is important for the realization of high performance graphene-based semiconductor devices, and thus, synthesis uniform large-area BLG required. Here we demonstrate highly film by chemical vapor deposition (CVD) over epitaxial Cu−Ni (111) binary alloy catalysts. The relative concentration Ni Cu as well growth temperature cooling profile was found to strongly influence uniformity BLG. In particular, slow process after...
Abstract Hydrogen boride nanosheets (HB sheets) are facilely synthesized via ion-exchange treatment on magnesium diboride (MgB 2 ) in an acetonitrile solution. Optical absorption and fluorescence spectra of HB sheets indicate that their bandgap energy is 2.8 eV. According to first-principles calculations, optical seen at eV assigned the electron transition between σ-bonding states B H orbitals. In addition, density functional theory (DFT) calculations suggest other allowed from state...
Transition metal dichalcogenides (TMDs) exhibit unique properties and potential applications when reduced to one-dimensional (1D) nanoribbons (NRs), owing quantum confinement high edge densities. However, effective growth methods for self-aligned TMD NRs are still lacking. We demonstrate a versatile approach lattice-guided of dense, aligned MoS 2 NR arrays via chemical vapor deposition (CVD) on anisotropic sapphire substrates, without tailored surface steps. This method enables the synthesis...
The energetics of nanometer-scale ribbon edges a monolayer graphite sheet (graphene) is studied by using the local spin density approximation in functional theory. formation energy an armchair edge found to be smaller $1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ per atom than that zigzag clean graphene edges. For hydrogenated edges, we also find more stable $0.2\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ edge. Atomic configurations at and electronic structures near Fermi level ribbons are crucial...
Electron transport in bilayer graphene placed under a perpendicular electric field is revealed experimentally. Steep increase of the resistance observed high field; however, does not diverge even at low temperatures. The temperature dependence conductance consists two contributions: thermally activated (TA) conduction and variable range hopping (VRH) conduction. We find that for measured (0-1.3 V/nm) mobility gap extracted from TA behavior agrees well with theoretical prediction band opening...
The zigzag graphene nanoribbon (ZGNR) has an antiferromagnetic property, that is, the relative spin angle theta between two edges is 180 degrees . By using noncollinear first-principles calculations, we find magnetic phase of ZGNR can be controlled by injecting either electrons or holes: as carrier density increases, continuously decreases from to 0 , which indicates net magnetization possible. Either FET doping chemical found
Pancakes in tubes: Coronenes, a class of planar π-conjugated molecules, organize 1D structures when using single-walled carbon nanotubes (SWCNTs) as templates (see picture). Coronene columns with coaxial stacking SWCNTs exhibit characteristic fluorescence spectra that significantly differ from those isolated coronene molecules and three-dimensional crystals are related to their well-ordered structure. Detailed facts importance specialist readers published ”Supporting Information”. Such...
The crystal and electronic structures, electrochemical properties diffusion mechanism of NASICON-type Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> have been investigated based on the hybrid density functional Heyd–Scuseria–Ernzerhof (HSE06).
The carrier-density-dependent conductance and thermoelectric properties of large-area $\mathrm{Mo}{\mathrm{S}}_{2}$ $\mathrm{WS}{\mathrm{e}}_{2}$ monolayers are simultaneously investigated using the electrolyte gating method. sign power changes across transistor off-state in ambipolar as majority carrier density switches from electron to hole. thermopower factor monolayer samples one order magnitude larger than that bulk materials, their carrier-density dependences exhibit a quantitative...
Abstract Artificial van der Waals heterostructures of 2D layered materials are attractive from the viewpoint possible discovery new physics together with improved functionalities. Stacking various combinations atomically thin semiconducting transition metal dichalcogenides, MX 2 (M = Mo, W; X S, Se, Te) a hexagonal crystal structure, typically leads to formation staggered Type II band alignment in heterostructure, where electrons and holes confined different layers. Here, comprehensive...
Aligned growth of transition metal dichalcogenides and related two-dimensional (2D) materials is essential for the synthesis high-quality 2D films due to effective stitching merging grains. Here, we demonstrate controlled highly aligned molybdenum disulfide (MoS2) on c-plane sapphire with two distinct orientations, which are by tuning sulfur concentration. We found that size MoS2 grains smaller their photoluminescence weaker as compared those randomly oriented grains, signifying enhanced...
Recently, research on transition metal dichalcogenides (TMDCs) has been accelerated by the development of large-scale synthesis based chemical vapor deposition (CVD). However, in most cases, CVD-grown TMDC sheets are composed randomly oriented grains, and thus contain many distorted grain boundaries (GBs) which deteriorate physical properties TMDC. Here, we demonstrate epitaxial growth monolayer tungsten disulfide (WS2) sapphire introducing a high concentration hydrogen during CVD process....