Functionalized MoS(2) nanosheet-based field-effect biosensor for label-free sensitive detection of cancer marker proteins in solution.

Label-free MoS(2) nanosheet-based field-effect biosensor detects cancer marker protein Prostate Specific Antigen in real time with high sensitivity and selectivity, exhibiting great potential in point-of-care diagnostics application.

Printed all-solid flexible microsupercapacitors: towards the general route for high energy storage devices.

A novel method for fabricating all-solid flexible microsupercapacitors (MSCs) was proposed and developed by utilizing screen printing technology. A typical printed MSC is composed of a printed Ag electrode, MnO2/onion-like carbon (MnO2/OLC) as active material and a polyvinyl alcohol:H3PO4 (PVA:H3PO4) as solid electrolyte. A capacity of 7.04 mF cm(-2) was achieved for the screen printed MnO2/OLC MSCs at a current density of 20 µA cm(-2). It also showed an excellent cycling stability, with 80% retention of the specific capacity after 1000 cycles. The printed all-solid flexible MSCs exhibited remarkably high mechanical flexibility when the devices were bent to a radius of 3.5 mm. In addition, all-solid MSCs were successfully demonstrated by screen printing technique on various substrates, such as silicon, glass and conventional printing paper. Moreover, the screen printing technique can be extended to other active materials, such as OLC and carbon nanotubes. This method provides a general route for printable all-solid flexible MSCs, which is compatible with the roll-to-roll process for various high performance active materials.

Preparation of MoS2-MoO3 hybrid nanomaterials for light-emitting diodes.

A facile strategy to prepare MoS2 -MoO3 hybrid nanomaterials is developed, based on the heat-assisted partial oxidation of lithium-exfoliated MoS2  nanosheets in air followed by thermal-annealing-driven crystallization. The obtained MoS2 -MoO3 hybrid nanomaterial exhibits p-type conductivity. As a proof-of-concept application, an n-type SiC/p-type MoS2 -MoO3 heterojunction is used as the active layer for light-emitting diodes. The origins of the electroluminescence from the device are theoretically investigated. This facile synthesis and application of hybrid nanomaterials opens up avenues to develop new advanced materials for various functional applications, such as in electrics, optoelectronics, clean energy, and information storage.

MoS2 Surface Structure Tailoring via Carbonaceous Promoter.

Atomically thin semiconducting transition-metal dichalcogenides have been attracting lots of attentions, particularly, molybdenum disulfide (MoS2) monolayers show promising applications in field effect transistors, optoelectronics and valleytronics. However, the controlled synthesis of highly crystalline MoS2 remain a challenge especially the systematic approach to manipulate its structure and morphology. Herein, we report a method for controlled synthesis of highly crystalline MoS2 by using chemical vapor deposition method with carbonaceous materials as growth promoter. A uniform and highly crystalline MoS2 monolayer with the grain size close to 40 µm was achieved. Furthermore, we extend the method to the manipulation of MoS2 morphology, flower-shape vertical grown MoS2 layers were obtained on growth promoting substrates. This simple approach allows an easy access of highly crystalline MoS2 layers with morphology tuned in a controllable manner. Moreover, the flower-shape MoS2 grown on graphene oxide film used as an anode material for lithium-ion batteries showed excellent electrochemical performance.

Designed hybrid nanostructure with catalytic effect: beyond the theoretical capacity of SnO2 anode material for lithium ion batteries.

Transition metal cobalt (Co) nanoparticle was designed as catalyst to promote the conversion reaction of Sn to SnO2 during the delithiation process which is deemed as an irreversible reaction. The designed nanocomposite, named as SnO2/Co3O4/reduced-graphene-oxide (rGO), was synthesized by a simple two-step method composed of hydrothermal (1(st) step) and solvothermal (2(nd) step) synthesis processes. Compared to the pristine SnO2/rGO and SnO2/Co3O4 electrodes, SnO2/Co3O4/rGO nanocomposites exhibit significantly enhanced electrochemical performance as the anode material of lithium-ion batteries (LIBs). The SnO2/Co3O4/rGO nanocomposites can deliver high specific capacities of 1038 and 712 mAh g(-1) at the current densities of 100 and 1000 mA g(-1), respectively. In addition, the SnO2/Co3O4/rGO nanocomposites also exhibit 641 mAh g(-1) at a high current density of 1000 mA g(-1) after 900 cycles, indicating an ultra-long cycling stability under high current density. Through ex-situ TEM analysis, the excellent electrochemical performance was attributed to the catalytic effect of Co nanoparticles to promote the conversion of Sn to SnO2 and the decomposition of Li2O during the delithiation process. Based on the results, herein we propose a new method in employing the catalyst to increase the capacity of alloying-dealloying type anode material to beyond its theoretical value and enhance the electrochemical performance.

3D graphene supported MoO2 for high performance binder-free lithium ion battery.

In this work, we report the synthesis of MoO2 nanoparticles grown on three dimensional graphene (3DG) via the reduction of α-MoO3 nanobelts through a facile chemical vapor deposition (CVD) approach under argon protection gas environment. In this synthesis approach, the presence of hydrophobic 3DG promoted the Volmer-Weber growth of MoO2 nanoparticles (30-60 nm). The as-prepared MoO2-3DG nanocomposite was directly used as a binder-free anode electrode for lithium ion batteries (LIBs) without additives and exhibited excellent electrochemical performance. It delivered high reversible capacities of 975.4 mA h g(-1) and 537.3 mA h g(-1) at the current densities of 50 and 1000 mA g(-1), respectively. Moreover, the electrode also showed an increased capacity from 763.7 mA h g(-1) to 986.9 mA h g(-1) after 150 discharge and charge cycles at a current density of 200 mA g(-1). The enhanced electrochemical performance of MoO2-3DG nanocomposite electrode may be attributed to the synergistic effects of MoO2 nanoparticles and 3DG layers. This facile CVD synthesis process presents a feasible route for large-scale production of high performance, environmentally friendly electrode. In addition, this process also has the potential of being utilized in other materials for energy storage devices application.

Dual wavelength electroluminescence from CdSe/CdS tetrapods.

We fabricated a single active layer quantum dot light-emitting diode device based on colloidal CdSe (core)/CdS (arm) tetrapod nanostructures capable of simultaneously producing room temperature electroluminesence (EL) peaks at two spectrally distinct wavelengths, namely, at ∼500 and ∼660 nm. This remarkable dual EL was found to originate from the CdS arms and CdSe core of the tetrapod architecture, which implies that the radiative recombination of injected charge carriers can independently take place at spatially distinct regions of the tetrapod. In contrast, control experiments employing CdSe-core-seeded CdS nanorods showed near-exclusive EL from the CdSe core. Time-resolved spectroscopy measurements on tetrapods revealed the presence of hole traps, which facilitated the localization and subsequent radiative recombination of excitons in the CdS arm regions, whereas excitonic recombination in nanorods took place predominantly within the vicinity of the CdSe core. These observations collectively highlight the role of morphology in the achievement of light emission from the different material components in heterostructured semiconductor nanoparticles, thus showing a way in developing a class of materials which are capable of exhibiting multiwavelength electroluminescence.

Catalyst engineering for lithium ion batteries: the catalytic role of Ge in enhancing the electrochemical performance of SnO2(GeO2)0.13/G anodes.

The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO(2)/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO(20) and SnO(2) nanoparticles (<10 nm) were uniformly anchored on the graphene sheets via a simple single-step hydrothermal method. The synthesized SnO(2)(GeO(2))0.13/G nanocomposites can deliver a capacity of 1200 mA h g(-1) at a current density of 100 mA g(-1), which is much higher than the traditional theoretical specific capacity of such nanocomposites (∼ 702 mA h g(-1)). More importantly, the SnO(2)(GeO(2))0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g(-1) at a discharge current of 2000 mA g(-1)) and excellent long cycling stability (almost 100% retention after 600 cycles). The enhanced electrochemical performance was attributed to the catalytic effect of Ge, which enabled the reversible reaction of metals (Sn and Ge) to metals oxide (SnO(2) and GeO(2)) during the charge/discharge processes. Our demonstrated approach towards nanocomposite catalyst engineering opens new avenues for next-generation high-performance rechargeable Li-ion batteries anode materials.

Pre-lithiation of onion-like carbon/MoS2 nano-urchin anodes for high-performance rechargeable lithium ion batteries.

Hybrid urchin-like nanostructures composed of a spherical onion-like carbon (OLC) core and MoS2 nanoleaves were synthesized by a simple solvothermal method followed by thermal annealing treatment. Compared to commercial MoS2 powder, MoS2/OLC nanocomposites exhibit enhanced electrochemical performance as anode materials of lithium-ion batteries (LIBs) with a specific capacity of 853 mA h g(-1) at a current density of 50 mA g(-1) after 60 cycles, and a moderate initial coulombic efficiency of 71.1%. Furthermore, a simple pre-lithiation method based on direct contact of lithium foil with MoS2/OLC nano-urchins was used to achieve a very high coulombic efficiency of 97.6% in the first discharge/charge cycle, which is at least 26% higher compared to that of pristine MoS2/OLC nano-urchins. This pre-lithiation method can be generalized to develop other carbon-metal sulfide nanohybrids for LIB anode materials. These results may open up a new avenue for the development of the next-generation high-performance LIBs.

Synthesis, physical properties, and self-assembly of a novel asymmetric aroyleneimidazophenazine.

The synthesis, physical properties, and self-assembly of a novel asymmetric aroyleneimidazophenazine (IZ1) is reported. The as-prepared IZ1 nanowires display an obvious red fluorescence. A heterojunction light-emitting diode (LED) device with the structure ITO/IZ1 nanowires/p-SiC/Al (10 nm)/Ti (80 nm)/Al (380 nm)/ITO was fabricated, and electroluminescence emission with two peaks at about 412 nm and 613 nm was detected with a forward bias ranging from 5 to 10 V.

Self-assembly of hierarchical MoSx/CNT nanocomposites (2

Two dimension (2D) layered molybdenum disulfide (MoS2) has emerged as a promising candidate for the anode material in lithium ion batteries (LIBs). Herein, 2D MoSx (2 ≤ x ≤ 3) nanosheet-coated 1D multiwall carbon nanotubes (MWNTs) nanocomposites with hierarchical architecture were synthesized via a high-throughput solvent thermal method under low temperature at 200°C. The unique hierarchical nanostructures with MWNTs backbone and nanosheets of MoSx have significantly promoted the electrode performance in LIBs. Every single MoSx nanosheet interconnect to MWNTs centers with maximized exposed electrochemical active sites, which significantly enhance ion diffusion efficiency and accommodate volume expansion during the electrochemical reaction. A remarkably high specific capacity (i.e., > 1000 mAh/g) was achieved at the current density of 50 mA g(-1), which is much higher than theoretical numbers for either MWNTs or MoS2 along (~372 and ~670 mAh/g, respectively). We anticipate 2D nanosheets/1D MWNTs nanocomposites will be promising materials in new generation practical LIBs.

Wavelength tunable electroluminescence from randomly assembled n-CdS(x)Se(1-x) nanowires/p+-SiC heterojunction.

Visible electroluminescence (EL) with tunable wavelength has been observed at room temperature from randomly assembled n-CdS(x)Se(1-x) nanowires grown on a p(+)-SiC substrate by the vapor transport technique. The dominant emission peaks can be tuned from ∼720 to ∼520 nm by varying the composition of the alloy nanowires.

Synthesis, characterization, self-assembly, and physical properties of 11-methylbenzo[d]pyreno[4,5-b]furan.

Synthesis, structure, and physical properties of a novel 11-methylbenzo[d]pyreno[4,5-b]furan (BPF) and its self-assembly in water have been reported. The performance of nanowire-based films in organic light-emitting diodes is much better than that of the thin film deposited by directly drop-coating BPF molecules in THF solution. SEM study indicates that the well-organized structure (nanowires) is an important factor in enhancing the performance of OLED devices.