Using Fe doped titania powders as the precursor, Fe doped TiO2 nanotubes with small diameter of 10nm were obtained by hydrothermal method. The doped titania powders have two different crystalline phases, anatase and r...Using Fe doped titania powders as the precursor, Fe doped TiO2 nanotubes with small diameter of 10nm were obtained by hydrothermal method. The doped titania powders have two different crystalline phases, anatase and rutile of which the average particle diameters are 30.3nm and 41.7nm, receptively. The products were characterized by TEM, XRD and EDS. The results showed that Fe doped TiO2 nanotubes of 200nm in length could be obtained from Fe doped rutile powder, and have higher yields. The formation mechanism of long titania nanotubes was suggested in the light of the relative stability of crystalline phase.展开更多
Understanding energy dissipation and transport in nanoscale structures is of great importance for the design of energy-efficient circuits and energy-conversion systems.This is also a rich domain for fundamental discov...Understanding energy dissipation and transport in nanoscale structures is of great importance for the design of energy-efficient circuits and energy-conversion systems.This is also a rich domain for fundamental discoveries at the intersection of electron,lattice(phonon),and optical(photon)interactions.This review presents recent progress in understanding and manipulation of energy dissipation and transport in nanoscale solid-state structures.First,the landscape of power usage from nanoscale transistors(~10^(-8) W)to massive data centers(~10^(-9) W)is surveyed.Then,focus is given to energy dissipation in nanoscale circuits,silicon transistors,carbon nanostructures,and semiconductor nanowires.Concepts of steady-state and transient thermal transport are also reviewed in the context of nanoscale devices with sub-nanosecond switching times.Finally,recent directions regarding energy transport are reviewed,including electrical and thermal conductivity of nanostructures,thermal rectification,and the role of ubiquitous material interfaces.展开更多
Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero...Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.展开更多
Lithium metal is considered the ideal anode material for Li-ion-based batteries because it exhibits the highest specific capacity and lowest redox potential for this type of cells. However, growth of Li dendrites, uns...Lithium metal is considered the ideal anode material for Li-ion-based batteries because it exhibits the highest specific capacity and lowest redox potential for this type of cells. However, growth of Li dendrites, unstable solid electrolyte interphases, low Coulombic efficiencies, and safety hazards have significantly hindered the practical application of metallic Li anodes. Herein, we propose a three-dimensional （3D） carbon nanotube sponge （CNTS） as a Li deposition host. The high specific surface area of the CNTS enables homogenous charge distribution for Li nucleation and minimizes the effective current density to overcome dendrite growth. An additional conformal A1203 layer on the CNTS coated by atomic layer deposition （ALD） robustly protects the Li metal electrode/electrolyte interface due to the good chemical stability and high mechanical strength of the layer. The Li@ALD-CNTS electrode exhibits stable voltage profiles with a small overpotential ranging from 16 to 30 mV over 100 h of cycling at 1.0 mA·cm^-2. Moreover, the electrodes display a dendrite-free morphology after cycling and a Coulombic efficiency of 92.4% over 80 cycles at 1.0 mA·cm^-2 in an organic carbonate electrolyte, thus demonstrating electrochemical stability superior to that of planar current collectors. Our results provide an important strategy for the rational design of current collectors to obtain stable Li metal anodes.展开更多
Water treatment is the key to coping with the conflict between people＇s increasing demand for water and the world-wide water shortage. Owing to their unique and tunable structural, physical, and chemical properties, ...Water treatment is the key to coping with the conflict between people＇s increasing demand for water and the world-wide water shortage. Owing to their unique and tunable structural, physical, and chemical properties, carbon nanotubes （CNTs） have exhibited great potentials in water treatment. This review makes an attempt to provide an overview of potential solutions to various environmental challenges by using CNTs as adsorbents, catalysts or catalyst support, membranes, and electrodes. The merits of incorporating CNT to conventional water-treatment material are emphasized, and the remaining challenges are discussed.展开更多
文摘Using Fe doped titania powders as the precursor, Fe doped TiO2 nanotubes with small diameter of 10nm were obtained by hydrothermal method. The doped titania powders have two different crystalline phases, anatase and rutile of which the average particle diameters are 30.3nm and 41.7nm, receptively. The products were characterized by TEM, XRD and EDS. The results showed that Fe doped TiO2 nanotubes of 200nm in length could be obtained from Fe doped rutile powder, and have higher yields. The formation mechanism of long titania nanotubes was suggested in the light of the relative stability of crystalline phase.
基金This review was in part supported by the Nanoelectronics Research Initiative(NRI)the DARPA Young Faculty Award(No.HR0011-08-1-0035)+2 种基金the Office of Naval Research(No.N00014-09-1-0180)the National Science Foundation(No.CCF 08-29907)Intel Corp.,and Northrop Grumman.
文摘Understanding energy dissipation and transport in nanoscale structures is of great importance for the design of energy-efficient circuits and energy-conversion systems.This is also a rich domain for fundamental discoveries at the intersection of electron,lattice(phonon),and optical(photon)interactions.This review presents recent progress in understanding and manipulation of energy dissipation and transport in nanoscale solid-state structures.First,the landscape of power usage from nanoscale transistors(~10^(-8) W)to massive data centers(~10^(-9) W)is surveyed.Then,focus is given to energy dissipation in nanoscale circuits,silicon transistors,carbon nanostructures,and semiconductor nanowires.Concepts of steady-state and transient thermal transport are also reviewed in the context of nanoscale devices with sub-nanosecond switching times.Finally,recent directions regarding energy transport are reviewed,including electrical and thermal conductivity of nanostructures,thermal rectification,and the role of ubiquitous material interfaces.
基金financial support of International Center for Young Scientists(ICYS)World Premier International Center for Materials Nanoarchitectonics(WPI-MANA) in National Institute for Materials Science(NIMS)financial support from KAKENHI project(Grant-in-Aid for Young Scientists,26820322) of Japan Society for the Promotion of Science(JSPS)
文摘Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.
文摘Lithium metal is considered the ideal anode material for Li-ion-based batteries because it exhibits the highest specific capacity and lowest redox potential for this type of cells. However, growth of Li dendrites, unstable solid electrolyte interphases, low Coulombic efficiencies, and safety hazards have significantly hindered the practical application of metallic Li anodes. Herein, we propose a three-dimensional （3D） carbon nanotube sponge （CNTS） as a Li deposition host. The high specific surface area of the CNTS enables homogenous charge distribution for Li nucleation and minimizes the effective current density to overcome dendrite growth. An additional conformal A1203 layer on the CNTS coated by atomic layer deposition （ALD） robustly protects the Li metal electrode/electrolyte interface due to the good chemical stability and high mechanical strength of the layer. The Li@ALD-CNTS electrode exhibits stable voltage profiles with a small overpotential ranging from 16 to 30 mV over 100 h of cycling at 1.0 mA·cm^-2. Moreover, the electrodes display a dendrite-free morphology after cycling and a Coulombic efficiency of 92.4% over 80 cycles at 1.0 mA·cm^-2 in an organic carbonate electrolyte, thus demonstrating electrochemical stability superior to that of planar current collectors. Our results provide an important strategy for the rational design of current collectors to obtain stable Li metal anodes.
基金the financial support from the Program for the New Century Excellent Talents in Universities of China(No.NCET-10-0489)the Natural Science Foundation of China(No.21107045) the Natural Science Foundation of Jiangsu Province of China(No.BK2011575)
文摘Water treatment is the key to coping with the conflict between people＇s increasing demand for water and the world-wide water shortage. Owing to their unique and tunable structural, physical, and chemical properties, carbon nanotubes （CNTs） have exhibited great potentials in water treatment. This review makes an attempt to provide an overview of potential solutions to various environmental challenges by using CNTs as adsorbents, catalysts or catalyst support, membranes, and electrodes. The merits of incorporating CNT to conventional water-treatment material are emphasized, and the remaining challenges are discussed.
