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Herein we develop a facile strategy for fabricating nickel particle encapsulated in few-layer nitrogen-doped graphene supported by graphite carbon sheets as a high-performance electromagnetic wave (EMW) absorbing material. The obtained material exhibits sheetlike morphology with a lateral length ranging from a hundred nanometers to 2 μm and a thickness of about 23 nm. Nickel nanoparticles with a diameter of approximately 20 nm were encapsulated in about six layers of nitrogen-doped graphene. As applied for electromagnetic absorbing material, the heteronanostructures exhibit excellent electromagnetic wave absorption property, comparable to most EMW absorbing materials previously reported. Typically, the effective absorption bandwidth (the frequency region falls within the reflection loss below -10 dB) is up to 8.5 GHz at the thicknesses of 3.0 mm for the heteronanostructures with the optimized Ni content. Furthermore, two processes, carbonization at a high temperature and subsequent treatment in hot acid solution, were involved in the preparation of the heteronanostructures, and thus, mass production was achieved easily, facilitating their practical applications.

MoSe2 nanosheets with ultrathin thickness and rich defects were grown on the surface of carbon fiber cloth by a facile solvent-thermal method. The active area and conductivity of the MoSe2 catalyst were increased simultaneously because of the NH4F etching effect and its incorporation with carbon fiber cloth. As a result, the MoSe2-based catalysts exhibited excellent HER activity including small onset potential, large exchange current density and small Tafel slope, which is superior to most of MoSe2-based catalysts reported previously.

A novel three-dimensional graphene aerogel–ZnO spheres composite has been synthesized via a simple solvothermal method. The three-dimensional graphene exhibits interconnected macroporous networks and the ZnO spheres featured a size of 0.5–1 μm are anchored homogeneously on the surface of graphene layers. When being used as gas sensors for detection of NO2, the porous graphene–ZnO composite achieves a higher response and fast response/recovery behavior at room temperature effectively (RT). The enhancement of the sensing response is mainly attributed to the improved conductivity, the 3D porous structure of graphene and the interaction between p-type graphene and n-type zinc oxide. The sensing mechanism of the composite is also discussed.

In this paper, decorating Ag3PO4/Bi2MoO6 heterostructures with uniformly dispersed ultrafine Ag nanoparticles are obtained by a combination of solvothermal technique, deposition–precipitation method and in situ photoreduction process. Two visible-light active components (Ag3PO4, Bi2MoO6) and the electron-transfer system (Ag) are spatially fixed in this heterostructures system. The photocatalytic studies revealed that the heterostructures system exhibits enhanced photocatalytic activity than the Bi2MoO6 and Ag3PO4/Bi2MoO6 heterostructures under visible light. The enhanced photocatalytic activity can be attributed to the effective separation of photogenerated carriers driven by the matching band potentials between Ag3PO4 and Bi2MoO6, as well as the good electron trapping role of Ag nanoparticles in situ formed on the surfaces of Ag3PO4 particles during the photocatalytic reaction.

One-dimensional Bi 4 Ti 3 O 12 nanofibers were synthesized by an electrospinning method. Subsequently, through a simple in situ ion-exchange reaction between the Bi 4 Ti 3 O 12 nanofibers and thioacetamide, Bi 4 Ti 3 O 12 /Bi 2 S 3 hierarchical heterostructures were successfully fabricated. Controlled partial ion exchange brings about the close interconnection between the semiconductors to benefit the separation of carriers. The Bi 4 Ti 3 O 12 /Bi 2 S 3 heterostructures exhibited enhanced photocatalytic performance under visible light. The improved photocatalytic activities are attributed to the visible light absorption enhanced by Bi 2 S 3 and the formation of a heterojunction between Bi 4 Ti 3 O 12 and Bi 2 S 3 , which can effectively accelerate the charge separation and transfer.

In this paper, Cd(OH)2 1D three-side nanobelt architectures have been fabricated through a facile two-phase reaction system. Considering their electropositive character proven by zeta potential measurement, the as-obtained Cd(OH)2 nanomaterials have been applied to capture negatively charged DNA. On the basis of the above results, the Cd(OH)2 nanomaterials have been employed for trapping negatively charged double-stranded DNA molecules (salmon sperm DNA). Assisted by the detailed observation of their DNA interaction results as well as through UV–vis spectroscopy, infrared imaging automatic target recognition (IRATR) and inductive coupled plasma atomic emission spectrometer (ICP-AES) measurements, it has been clearly shown that this 1D nanoarchitecture can effectively trap and release DNA molecules without use of any other organic reagents. In addition, a miniaturized electrochemical DNA-releasing device based on the Cd(OH)2 1D three-side nanobelt architectures has been fabricated. Using this device, it is...

Ni3−xCoxS4 (x = 1.5, 2, 2.25, 2.5) nanotube arrays were prepared on carbon cloth by a two-step hydrothermal route and their electrochemical performance was studied. The aspect ratios and electrochemical performance of the Ni–Co sulfide nanotube arrays can be well controlled by manipulating the Co/Ni molar ratio. With the cooperation of the appropriate morphology and compositions, the specific capacitance of Ni0.75Co2.25S4 can reach as high as 1856 F g−1 at 1 A g−1. The rate capability is 88% at a high current density of 50 A g−1. The superior electrochemistry performance demonstrates that Ni–Co sulfide nanotube arrays with an appropriate molar ratio of Co/Ni would be promising for high-performance supercapacitor materials.

Three-dimensional graphene aerogel-supported Fe3O4 nanoparticles for efficient detection of NO2 at room temperature are reported. The graphene composite exhibits an interconnected macroporous framework of graphene sheets with uniform dispersion of Fe3O4 nanoparticles. Such a hybrid nanostructure would effectively facilitate target gas diffusion and exhibit significantly higher response and faster recovery speed than pure reduced graphene oxide, highlighting the importance of the 3D macropores and high specific surface area of the graphene aerogel support for improving sensing performance. We also propose a hybrid sensing mechanism for the drastic improvement in the sensing behavior which combines the resistance modulation of Fe3O4 nanoparticles/graphene heterointerfaces in addition to the radial modulation of the surface depletion layer of the Fe3O4 nanocomposite.

The potential applications of quantum dots on wide band gap semiconductor structures in flexible and large-scale optoelectronics demand fundamental analysis of their tunable growth. Herein, PbS quantum dots (

Recently, significant progress has been achieved in paper electronics due to their potential technological applications in rollup displays, wearable devices and smart cards. However, it is still a challenge to efficiently form suitable structured materials on paper substrates due to their porous and rough surface. In this research, ZnO pomegranates composed of 8 nm ZnO nanodots, have been successively fabricated on a pencil drawn graphite-on-paper substrate by an eco-friendly and cost effective solvothermal method. Most significantly, this solution grown photoconductive photodetector shows good device performances with spectrum responsivity to ultraviolet light of 0.06 A W−1 and a quick response time of 4.3 s. Systematic analysis shows that the interface-related energy boundary modulation within ZnO pomegranates may facilitate the separation of photo-induced carriers, eventually resulting in its low dark current and quick response. Meanwhile, this structure designing strategy can be utilized for the future fabrication of high performance paper electronics with other materials. Besides, due to the firm attachment of ZnO pomegranates on the substrate, caused by the introduction of ethanol during the solvothermal growth process and ultrasonic vibration during the formation of the ZnO seed layer, this device is also a highly flexible and rolled-up photodetector with good reversible characteristics and steady performance towards bending deformations and irradiation degradation.

One-dimensional TiO2 nanofibers were synthesized using an electrospinning method. Subsequently, Ag3PO4/TiO2 heterostructures were successfully fabricated through a simple deposition–precipitation reaction. The Ag3PO4/TiO2 heterostructures exhibited enhanced photocatalytic performance under visible light. The improved photocatalytic activities are attributed to the visible light absorption enhanced by Ag3PO4 and the formation of a heterojunction between TiO2 and Ag3PO4, which can effectively accelerate the charge separation and transfer. The heterostructures can be reclaimed easily by sedimentation without a decrease in the photocatalytic activity due to the large length to diameter ratio of the nanofiber framework.

Novel hierarchical SnO2 hollow nanospindles self-assembled from nanorods have been successfully synthesized via a templating approach under hydrothermal conditions. The influence of the reactant concentration on SnO2 products is investigated in detail. It is found that the interplay of the acidic etching of Fe2O3 templates and controlled hydrolysis of SnCl2 is significant for the formation of the hierarchical SnO2 hollow nanostructures. The evolution process and formation mechanism of the hollow structures with nanorods are analyzed from the angle of nucleation and morphology. Moreover, the electrochemical properties of the hollow structures are also studied by charge–discharge cycling, the result displays that the hierarchical SnO2 hollow nanostructure exhibits much better lithium storage properties with higher reversible capacities and enhanced cyclic capacity retention than the commercial SnO2 nanoparticles.

Hollow structures with hierarchical architecture and multi-composition have attracted extensive interest because of their fascinating physicochemical properties as well as wide applications. Herein we report the designed synthesis of hierarchical nanosheet-based CoMoO4–NiMoO4 nanotubes by a hydrothermal treatment and a subsequent calcination method. The walls of the hierarchical nanotubes are composed of interconnected NiMoO4 nanosheets and CoMoO4 nanoparticles anchored on the surface of the nanosheets. The diameter of the hollow interior, the thickness of NiMoO4 nanosheets and the diameter of CoMoO4 nanoparticles are around 180 nm, less than 6 nm and 3 nm, respectively, providing the hierarchical nanotubes with a high surface area and a large pore volume. When evaluated as electrodes for pseudocapacitors, the hierarchical nanotubes with an appropriate amount of CoMoO4 show a high specific capacitance of 1079 F g−1 at a current density of 5 A g−1 and excellent stability with 98.4% capacitance retention after 1000 cycles. Furthermore, an asymmetric capacitor, consisting of active carbon and hierarchical nanosheet-based CoMoO4–NiMoO4 nanotubes as negative and positive electrodes, respectively, delivers an energy density of 33 W h kg−1 at a power density of 375 W kg−1, and 16.3 W h kg−1 even at a high power density of 6000 W kg−1. The supercapacitive properties are much higher than those of single-phase NiMoO4 nanotubes, and most of the other metal molybdates and metal oxides reported previously. Besides, the hierarchical nanotubes also exhibit much better electrocatalytic activity for the oxygen evolution reaction than single-phase NiMoO4 nanotubes, and most of the other metal molybdates and metal oxides. Our results demonstrate the importance of rational design of complex hollow structures with enhanced properties for a wide range of practical applications.

Aurivillius oxide semiconductors are important photocatalyst because of their unique electronic structure and layered crystal. In this paper, two kinds of Aurivillius oxide semiconductors heterostructures based on Bi 4 Ti 3 O 12 nanofibers frameworks and BiOCl nanosheets are successfully synthesized by combining the electrospinning technique and solvothermal method. The high-resolution transmission electron microscopy results reveal that an intimate interface between Bi 4 Ti 3 O 12 nanofibers and BiOCl nanosheets forms in the heterojunctions. Photocatalytic tests show that the BiOCl/Bi 4 Ti 3 O 12 heterostructures exhibit enhanced photocatalytic activity than bare Bi 4 Ti 3 O 12 and BiOCl, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the BiOCl/Bi 4 Ti 3 O 12 heterojunction. At the end, the photocatalytic mechanism with O 2 − production was studied.

One-dimensional ternary hierarchical heterostructures based on BiOCl nanosheets and bicrystalline TiO2 nanofiber frameworks that consist of anatase-rutile (AR) mixed phase TiO2 nanoparticles were successfully designed by combining the electrospinning technique and solvothermal method. The BiOCl nanosheets were uniformly grown onto the electrospun TiO2 nanofibers, and the density of the secondary BiOCl nanosheets could be controlled by adjusting the precursor concentration. Photocatalytic tests displayed that the ternary BiOCl/TiO2 (AR) hierarchical heterostructures possessed a much higher degradation rate than the bare bicrystalline TiO2 (AR) nanofibers, BiOCl/TiO2 (A) or BiOCl/TiO2 (R) composite. It is mainly attributed to the photogenerated interfacial charge transfer based on the photosynergistic effect of the heterojunctions, which results in the high separation efficiency of photogenerated electron-hole pairs.

Two-dimensional titanium carbide has gained considerable attention in recent years as an electrode material for supercapacitors due to its high melting point, good electrical conductivity, hydrophilicity and large electrochemically active surfaces. However, the irreversible restacking during synthesis restricts its development and practical applications. Here, Ti

Three-dimensional (3D) MoS

A porous hybrid g-C3N4/RGO (CNRG) material has been fabricated through a facile hydrothermal process with the help of glucose molecules, and serves as an efficient immobilization substrate to support ultrathin Ni(OH)2 nanosheets under an easy precipitation process. It was found that the g-C3N4 flakes can uniformly coat on both sides of the RGO, forming sandwich-type composites with a hierarchical structure. It is worth noting that the introduction of the g-C3N4 can effectively achieve the high dispersion and avoid the agglomeration of the nickel hydroxide, and significantly enhance the synthetically capacitive performance. Owning to this unique combination and structure, the CNRG/Ni(OH)2 composite possesses large surface area with suitable pore size distribution, which can effectively accommodate the electrolyte ions migration and accelerate efficient electron transport. When used as electrode for supercapacitor, the hybrid material exhibits high supercapacitive performance, such as an admirable specific capacitance (1785 F/g at a current density of 2 A/g), desirable rate stability (retain 910 F/g at 20 A/g) and favorable cycling durability (maintaining 71.3% capacity after 5000 cycles at 3 A/g). Such desirable properties signify that the CNRG/Ni(OH)2 composites can be a promising electrode material in the application of the supercapacitor.

A facile strategy has been adopted for the preparation of ZnFe2O4/NRG composite by anchoring ultrasmall ZnFe2O4 nanoparticles on nitrogen-doped reduced graphene (denoted as NRG) for high-performance supercapacitor electrode. Remarkably, the growth of ZnFe2O4 nanocrystals, the reduction of graphitic oxide and the doping of nitrogen to graphene have been simultaneously achieved in one process. It is found that the NRG employed as substrate can not only control the formation of nano-sized ZnFe2O4, but also guarantee the high dispersion without any agglomeration. Benefiting from this novel combination and construction, the hybrid material has large surface area which can provide high exposure of active sites for easy access of electrolyte and fast electron transport. When served as supercapacitor electrode, the ZnFe2O4/NRG composite exhibits a favorable specific capacitance of 244 F/g at 0.5 A/g within the potential range from −1 to 0 V, desirable rate stability (retain 131.5 F/g at 10 A/g) and an admirable cycling durability of 83.8% at a scan rate of 100 mV/s after 5000 cycles. When employed as symmetric supercapacitor, the device demonstrates favorable performance. These satisfactory properties of the ZnFe2O4/NRG composite can make it be of great promise in the supercapacitor application.

Coupling ultrasmall Fe2O3 particles (~4.0 nm) with the MoS2 nanosheets is achieved by a facile method for high-performance anode material for Li-ion battery. MoS2 nanosheets in the composite can serve as scaffolds, efficiently buffering the large volume change of Fe2O3 during charge/discharge process, whereas the ultrasmall Fe2O3 nanoparticles mainly provide the specific capacity. Due to bigger surface area and larger pore volume as well as strong coupling between Fe2O3 particles and MoS2 nanosheets, the composite exhibits superior electrochemical properties to MoS2, Fe2O3 and the physical mixture Fe2O3+MoS2. Typically, after 140 cycles the reversible capacity of the composite does not decay, but increases from 829 mA h g−1 to 864 mA h g−1 at a high current density of 2 A g−1. Thus, the present facile strategy could open a way for development of cost-efficient anode material with high-performance for large-scale energy conversion and storage systems.

Aurivillius oxide semiconductors are important photocatalysts because of their unique electronic structure and layered crystal. In this paper, two kinds of Aurivillius oxide semiconductor heterostructures based on Bi 4 Ti 3 O 12 nanofiber frameworks and Bi 2 XO 6 (X = Mo, W) nanosheets are successfully synthesized by combining the electrospinning technique and solvothermal method. The high-resolution transmission electron microscopy results reveal that an intimate interface between Bi 4 Ti 3 O 12 nanofibers and Bi 2 MoO 6 or Bi 2 WO 6 nanosheets forms in the heterojunctions. Photocatalytic tests show that the Bi 4 Ti 3 O 12 /Bi 2 XO 6 (X = Mo, W) heterostructures exhibit enhanced photocatalytic activity than bare Bi 4 Ti 3 O 12 and Bi 2 XO 6 (X = Mo, W) under visible light, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the Bi 4 Ti 3 O 12 /Bi 2 XO 6 heterojunction. The heterostructures can be reclaimed easily by sedimentation without a decrease of the photocatalytic activity due to the large length to diameter ratio of nanofiber frameworks. Moreover, such simple and versatile strategy can provide a general way to fabricate other heterostructures of Bi(III)-containing oxides, such as Bi 4 Ti 3 O 12 /BiVO 4 and Bi 4 Ti 3 O 12 /BiOCl.

A special core/shell/shell structured NaYF4/NaYF4:Yb3+,Er3+/NaYF4 (CSS) nanocrystal was designed to ensure each luminescence center in the emitting shell had the same surroundings. The nanocrystal includes a support core NaYF4 nanoparticle in the center coated by a thin emitting shell NaYF4:Yb3+,Er3+ and another NaYF4 shell with adjustable thickness as the outer shielding shell. The green upconversion fluorescence intensity Ig(d) of the CSS nanoparticles shows an exponential relationship with the thickness d of the shielding shell. When d decreased to 0, Ig(0) was ~356 times smaller than Ig(∞) due to the drastic fluorescence quenching of the rare earth luminescence centers by the surroundings. Our experimental results indicate that ~90% of the severe effect of the surroundings can be eliminated by coating with a ~4 nm-thick NaYF4 shielding shell.

“ZnO/ZnS superlattice” nanostructures were synthesized via a chemical vapor deposition process. The lattice mismatch between ZnO and ZnS induced defects within the thin superlattice as well as defo...

In this work, periodic arrays of various ZnO nanostructures were fabricated on both Si and GaN substrates via a facile hydrothermal process. To realize the site-specific growth, two kinds of masks were introduced. The polystyrene (PS) microsphere self-assembled monolayer (SAM) was employed as the mask to create a patterned seed layer to guide the growth of ZnO nanostructures. However, the resulting ZnO nanostructures are non-equidistant, and the diameter of the ZnO nanostructures is uncontrollable. As an alternative, TiO2 sol was used to replicate the PS microsphere SAM, and the inverted SAM (ISAM) mask was obtained by extracting the PS microspheres with toluene. By using the ISAM mask, the hexagonal periodic array of ZnO nanostructures with high uniformity were readily produced. Furthermore, the effect of the underlying substrates on the morphology of ZnO nanostructures has been investigated. It is found that the highly ordered and vertically aligned ZnO nanorods epitaxially grow on the GaN substrate, while the ZnO nanoflowers on Si substrates are random oriented.

To improve the efficiency of overall water splitting, highly active and stable bifunctional electrocatalysts are highly desirable. Herein, we fabricated mixed Ni–Co phosphides (Ni1−xCox–P) as bifunctional catalysts for overall water splitting. Structural characterizations indicated that the Ni1−xCox–P catalysts (0 > x > 1) exhibited hierarchical yolk-shelled morphologies, with a total diameter of 1–2 μm. Interestingly, the shell was assembled by numerous nanosheets with a thickness less than 10 nm. The electrochemical measurements indicated that the Ni1−xCox–P catalysts (0 < x < 1) showed significantly enhanced OER and HER activities in comparison to the pure Ni–P and Co–P catalysts, and the highest OER and HER activities were achieved as x = 0.31. To drive a current density of 10 mA cm−2, the Ni0.69Co0.31–P catalyst required an overpotential of 266 mV for OER and 96 mV for HER, respectively. The alkaline water electrolyzer with the Ni0.69Co0.31–P catalysts as the cathode and anode catalysts required a cell voltage of ca. 1.59 V to achieve a current density of 10 mA cm−2, which was comparable to the integrated performance of commercial Pt/C and IrO2. Furthermore, the electrolyzer assembled by the bufictional electrocatalysts showed a more stable performance than one assembled by commercial Pt/C and IrO2 operated at the simialr current density. The superior activity and long-term stability demonstrate that the hierarchical mixed Ni–Co phosphides have promising potential for application in large-scale water splitting.

MoSe

A facile strategy has been adopted for the preparation of ZnFe2O4/NRG composite by anchoring ultrasmall ZnFe2O4 nanoparticles on nitrogen-doped reduced graphene (denoted as NRG) for high-performance supercapacitor electrode. Remarkably, the growth of ZnFe2O4 nanocrystals, the reduction of graphitic oxide and the doping of nitrogen to graphene have been simultaneously achieved in one process. It is found that the NRG employed as substrate can not only control the formation of nano-sized ZnFe2O4, but also guarantee the high dispersion without any agglomeration. Benefiting from this novel combination and construction, the hybrid material has large surface area which can provide high exposure of active sites for easy access of electrolyte and fast electron transport. When served as supercapacitor electrode, the ZnFe2O4/NRG composite exhibits a favorable specific capacitance of 244 F/g at 0.5 A/g within the potential range from −1 to 0 V, desirable rate stability (retain 131.5 F/g at 10 A/g) and an admirable cycling durability of 83.8% at a scan rate of 100 mV/s after 5000 cycles. When employed as symmetric supercapacitor, the device demonstrates favorable performance. These satisfactory properties of the ZnFe2O4/NRG composite can make it be of great promise in the supercapacitor application.

An alkaline electrolyzer fabricated by employing hollow CoP nanoparticles/N-doped graphene as bifunctional catalysts exhibits remarkable activity with a current density of 10 mA cm(-2) at a cell voltage of 1.58 V and considerable stability over 65 h of continuous electrolysis operation, favorably comparable to the integrated performance of commercial Pt/C and IrO2.

Vertically aligned rutile TiO2 nanowire arrays (NWAs) with lengths of ∼44 μm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2 NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2 NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2 NWA based DSCs so far.

Novel hierarchical ZnO hexagonal towers were fabricated via chemical vapor deposition for the first time by adding trace Fe power in the precursor as a catalyst. The scanning electron microscopy images showed that the outside surface of novel hierarchical ZnO hexagonal towers was layer-by-layer assembly. X-ray diffraction pattern indicated that the hierarchical ZnO hexagonal towers grew preferentially along the [0 0 0 1] direction. Intense UV emission centered at 380 nm was observed at room temperature. Moreover, their field-emission properties were studied. A low turn-on electric field of 2.37 V μm−1 and high field enhancement factor of about 2691 were obtained, due to the novel layer structure and high crystalline quality. This kind of hierarchical ZnO microstructures could be a good candidate for high performance field emission devices.

Using Monte Carlo simulation method, we studied the influence of the disorder, eigenenergy and bandwidth on the localization length in disordered system. The results reveal that electronic states of system exhibited localization phenomena with the increase of degree of disorder and the localization length can be reduced by the increasing of disorder degree. Moreover the incremental range of localization length had a trend to descend with increase of bandwidth.

Ga-doped In2O3(ZnO)3 nanobelts were successfully fabricated via a simple chemical vapor deposition (CVD) process. The morphology, microstructure, and composition of the nanobelts were characterized by scanning electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy. The results confirm the formation of In2O3(ZnO)3 superlattice nanobelts doped with Ga. The field-emission studies show a low turn-on electrical field, high field enhancement factor, and a good stability of the emission current. These results are valuable for the design, fabrication, and optimization of field emitters.

Controlled synthesis of Al3+ doped ZnO hexagonal nanoplates was achieved via a facile one-step hydrothermal approach. The thicknesses of nanoplates, ranging from about 60 nm to 200 nm, can be controlled by variation of Al3+ concentration. A possible mechanism was proposed for the growth of a ZnO nanoplate and Al3+ cations played a crucial role for the shape-controlled synthesis. The photoluminescence spectra clearly showed a blue shift with the increasing Al3+ content.

High-quality ZnO nanocombs were synthesized on Si substrates coated with Au films by evaporating ZnO powders with a high yield. The morphology of the ZnO nanocombs was characterized by scanning electronic microscopy. In order to study the dynamic process of near-band edge emission, the temperature-dependent photoluminescence spectra were measured. The first excited state emission of A-free exciton centered at 3.403 eV was observed at 87 K.

N–In codoped ZnO nanobelts were successfully synthesized via high-temperature chemical vapor deposition for the first time, using the mixture of In/ZnO as a precursor. The EDX spectrum showed that In was introduced into ZnO nanobelts. In order to better understand the optical properties of N–In codoped ZnO nanobelts, the Raman and low-temperature PL spectra of the undoped, In-doped and N–In codoped ZnO nanostructures were measured. By contrasting, N is incorporated into the nanobelts. The temperature dependent photoluminescence (PL) spectra were investigated. Their PL spectra in the temperature from 9 K to room temperature were dominated by an AoX emission of excitons bound to 2No–InZn acceptor complexes. The dissociation energy of the acceptor complexes is estimated to be 89–112 meV.

We designed and successfully synthesized novel SiOx/ZnO heterostructures via one-step thermal reaction route. Orbicular SiOx dots regularly and alternately arrange in the middle of the up/down surfaces of a nanobelt to form a one-dimensional SiOx dot array, respectively, by their self-assembly. A high-resolution transmission electron microscopy study and a selected area electron diffraction pattern revealed that ZnO nanobelts are crystalline while SiOx dots are amorphous. The formation process of such heterostructure is discussed in terms of the Stranski–Krastanow growth mode of semiconductor quantum dots. Strong white luminescence was observed by bare eyes when the photoluminescence spectrum was measured.

Aligned ZnCdSe alloy nanostructures have been grown on GaAs (100) substrates using metalorganic chemical vapor deposition. Scanning electron microscopy observations find that they resemble nano-arr...

One-dimensional In2O3(ZnO)m superlattice wires were first synthesized on silicon substrates by evaporating a mixture of In and ZnO powders. The high-resolution transmission electron microscopy image indicates that the wires have a superlattice structure along their length, which consists of alternating stacks of an InO2− octahedral layer, as an inversion boundary, and an InO+(ZnO)m slab. Each slab is further separated by many triangular (zigzag) shape-contrast boundaries. They are secondary polarity inversion boundaries formed by 5-fold coordinated In and Zn atoms. The formation of such superlattice nanostructures is explained by the zigzag model. The PL properties of the superlattice nanostructures are discussed with regard to its temperature dependence for the first time.

Highly aligned nanowire bundles were controllably fabricated through the reaction of Si with oxygen, using molten Ga and Au as catalysts. Scanning electron microscopy reveals that the bundles have the ability to self-assemble into various morphologies, a few of which, including one that strikingly resembles a sunflower, were not reported before. Examinations of the bundles by transmission electron microscopy show that they contain fine, amorphous SiOx nanowires, with x ranging from 1.2 to 1.5. In the sunflower-like morphology, highly packed bundles form the disc florets and loosely packed bundles around the rim of the disc form the ray florets. We have studied the conditions under which the sunflower-like morphology could be obtained and suggest a possible mechanism for its growth. Room-temperature cathodoluminescence spectra of the nanowire bundles show that they emit an intense broad-band light covering the entire visible range.

We fabricated ZnCdSe alloy three-bladed nanoarrowheads (TBNAs) on GaAs (001) substrates by metalorganic chemical vapor deposition. On the basis of crystallographic analyses of their structure, we found that they are closely related to nanotetrapods, despite the apparent difference in morphology. A new quadra-twin core model is proposed to understand the growth of TBNAs. This model also agrees with reported results of a subclass of nanotetrapods that cannot be explained by conventional zinc blende and octa-twin core models. Furthermore, a simple method to distinguish the core structures by TEM is suggested.

Gallium oxide nanowires were synthesized on Si (001) substrate by chemical vapor deposition, using a Ga/Ga2O3 mixture as a precursor and Au as a catalyst. The structure of the as-synthesized products was examined by X-ray powder diffraction and high-resolution transmission electron microscopy, and found to be monoclinic β-Ga2O3. The morphologies of the β-Ga2O3 nanowires were characterized by scanning electron microscopy. The majority of the nanowires contain holes along their length, but a few were also found without holes. The holes are believed to be formed by the reaction of adsorbed Ga droplets on reactive terminating surfaces of the nanowires. For nanowires where these reactive surfaces are not exposed, the reaction of Ga is retarded. Cathodoluminescence (CL) of the nanowires was measured. Three emission bands centered at 376, 454, and 666 nm, respectively, were observed.

Uniform and smooth AlN nanosheets were fabricated on Si substrates by a vapour-phase transport method, using Al powder and ammonia as the source materials. Their morphology and structure were examined by scanning and transmission electron microscopy, and X-ray diffraction. They have a perfect rectangular shape. The growth is favoured along the 〈 1 1 00 〉 and 〈 0001 〉 crystallographic directions within the 〈 11 2 0 〉 plane. Their growth mechanism is discussed on the basis of data gathered. The linewidth of E 2 (high) longitudinal optical phonon mode is about 7 cm−1, indicating their high quality. Their photoluminescence property is also investigated.

Synthesis of Er-doped silicon-rich silicon oxide (SRSO) nanofibers bundled into yarns was successfully achieved. Photoluminescence (PL) studies of the yarns detected a strong and sharp band at 1.530 μm at room temperature, which is attributed to Er ions excited by energy transfer from photogenerated carriers in Si nanoclusters (nc-Si). The effective absorption cross-section of the first excited state of the Er ions is estimated to be 1.86 x 10 -16 cm -2 , higher by several orders of magnitude than that in an Er-doped SiO 2 host, due to the presence of nc-Si that serves as a sensitizer in the SRSO nanofibers. In order to investigate the luminescence mechanism of the Er ions, PL spectra excited by incident light of different wavelengths were measured. We found that both the peak position and line shape of the Er ion emissions are unaffected by the incident wavelength. The results indicate that the Er ion luminescence in the SRSO nanofibers is completely dominated by ions located at sites that are strongly coupled to the carriers in the nc-Si. We also found that the intensity of luminescence decreases by less than 30% as the temperature is raised from 10 K to room temperature, indicating that thermal quenching is significantly reduced.

Super-uniform single crystal ZnO nanohelices synthesized by Sb induced thermal evaporation is reported. The ZnO nanohelices as a whole have an axial direction of 〈 0001 〉 , perfect hexagonal cross section and length of tens of micrometres. There are six blocks in each period of the helices, and they grow along six equivalent directions 〈 0 1 11 〉 . The typical pitch distance, mean diameter and thickness of the nanowire is about 600, 400 and 100 nm. Calculation according to a simple model shows that the helical structure is energetically favourable. It could be used as photonic crystals or construct blocks in nanoscale optoelectronic and electromechanical systems. In addition to ZnO nanohelices, zigzag ZnO nanostructures were also obtained.

GaN nanorods were synthesized from the reaction of a Ga/Ga2O3 mixture with NH3 on Si substrates by chemical vapor deposition. The synthesized products were characterized by scanning and transmission electron microscopy, X-ray diffraction, photoluminescence and Raman spectroscopy. The nanorods are highly single crystalline and possess uniform smooth surfaces. PL revealed only a strong emission at 3.268 eV, ascribed to free exciton (FX) transitions, at room temperature; while the well-known yellow luminescence band centered at 2.2–2.3 eV was not detected. Four first-order phonon modes, corresponding to the A1(TO), E1(TO), E2(high), and A1(LO) at ∼531, 554, 564, and 721 cm−1, respectively, were observed by Raman backscattering. The red-shift of the FX emission peak and the down-shifts of the Raman modes by a few wave numbers are attributed to the presence of tensile strain inside GaN nanorods.

Well-aligned ZnSe nanowires and nanorods can be grown on ZnSe epilayers on different GaAs substrates, with and without catalyst, by metal-organic chemical vapor deposition. Gold particles affect the number density, growth direction, and the morphology of the resulting nanostructures. In the absence of the gold catalyst, hexagonal nanorods grow along the111directions. Growth defects on the epilayers may be the nucleation sites of the nanorods.

Nitrogenated tetrahedral amorphous carbon (ta-C:N) thin films have been prepared by a pulsed filtered vacuum arc deposition system at various conditions. The chemical composition and structure of the ta-C:N films were investigated by Non-Rutherford backscattering spectroscopy, Auger electron spectroscopy, Raman, and Fourier transform infrared transmission measurements. It was observed that the amount of N atoms incorporated into the ta-C:N films, as well as the fraction and size of the sp2 clusters, increased with increasing nitrogen pressure during deposition. On the other hand, the substrate negative bias voltage has different effects on the composition and structure of the films. The N content initially rises with increasing substrate negative bias voltage and then starts to decrease as it is further increased, while the sp2 fraction increases monotonically with the increase of negative bias voltage. No or very few CN bond exists in the films. With increasing N content the components of the single CN and disorder activated CC diminish. The compressive stress in the films is found to decrease sharply with the increase of nitrogen content, and then keep almost constant when the N content is increased further.