Na-ion cathode materials with a fast charge and discharge behavior are needed to develop future high-energy sodium-ion batteries (SIBs). However, inevitably complicated phase transitions and sluggish kinetics during insertion and removal of Na+ in P2-type layered transition metal oxides generate structural instability and severe capacity decay. To get rid of such a dilemma, we report a structural optimization strategy to promote P2-type layered transition metal oxides with more (010) active planes as an efficient cathode for SIBs. As a result, as-prepared hexagonal-prism P2-type layered Na0.71Li0.09Mn0.6Co0.16Ni0.16O2 cathode with more (010) active planes delivers a reversible capacity of 120.1 mAh/g at 0.1 C, impressive rate capability of 52.7 mAh/g at 10 C, and long-term cycling stability (capacity retention of 95.6% over 200 cycles). The outstanding electrochemical performance benefited from the unique hexagonal-prism with more (010) active facets, which can effectively shorten the diffusion distances of Na+, increase the Na-ion migration dynamics and nanostructural stability during cycling verified by morphology characterization, Rietveld refinement, GITT, density functional theory calculations and operando XRD.

Efficient multifunction materials with strong electromagnetic wave (EMW) absorption and high thermal conductance play a pivotal role in addressing the heat accumulation and EM interference problems in miniaturized and integrated electronics. However, incompatibility between EMW absorption and heat conductance makes their simultaneous improvement a major challenging issue. In this work, flower-like porous gamma-Al2O3@Ni@C composites are successfully formulated via a hydrothermal-soaking-calcining route. The original findings of the concerted improvement in EMW absorption and heat conductance are reported. By controlling [Ni2+] and sintering temperature (T-s), the interfaces, components, and defects are modified to achieve synergistic enhancement in the performance of the target composites. Results show that the gamma-Al2O3@Ni@C composites formed at [Ni2+] = 2.0 M and T-s = 700 degrees C present an optimal thermal conductance of 2.84 W/(m center dot K) at a low filling ratio of 30 % due to the phonon/electron relay transmiss on in the 3D network of unique flower-like porous structures, clearly superior to gamma-Al2O3 and most of the other gamma-Al2O3-based composites. Meanwhile, the composites synchronously present a broad absorption band (4.24 GHz, beyond 90 % damping over 15.75 similar to 18.00 GHz) and strong absorption (-42.43 dB) relative to a 1.7 mm-thick specimen owing to the enhanced damping coefficient and EM parameters. The outstanding properties exhibited by the flower-like porous gamma-Al2O3@Ni@C composites suggest that they have promising prospects for application in EMW absorption and thermal management.

The sub-group element with low valence state and larger radius doping of a hybrid P2-layered Na0.5Li0.07Mn0.61Co0.16Ni0.16O2 were systematically investigated. The refined XRD results and operando XRD data revealed the improved Na-storage capability.

The surface state of all-inorganic cesium lead halide (CsPbX3) perovskite quantum dots (QDs) is a crucial factor for the performance of CsPbX3 QD-based optoelectronic devices. In this research, we demonstrate a rational and efficient approach for regulating the surface state of CsPbBr3 QDs by diluting surface ligands. With a systematic investigation of the optical properties of CsPbBr3 QDs from ensemble to a single particle by decreasing the surface ligands, we proposed that two competitive exciton decay pathways of single exciton deactivation, short-lived band-edge emission (similar to 3 ns) and long-lived surface trap-state emission (similar to 6-12 ns), are closely related to the emission behavior and optical properties of CsPbBr3 QDs. These findings are of significance in understanding the nature of surface ligand density, trap states, and their roles in the photoluminescence quantum yield and in improving the optical property, efficiency, and stability of CsPbX3 QD-based devices.

Because of their high reversible capacity and wide operation voltage window, P2-type layered transition metal oxides are considered as one type of potential cathode candidate for sodium-ion batteries. However, they still suffer from low kinetics, phase degeneration, and ambiguous mechanism of Na+ diffusion. Here, we synthesized a P2-type Na0.6Li0.07Mn0.66Co0.17Ni0.17O2 with a high Na+ diffusion performance by sintering a nanoplate-structural precursor with alkali metal salt and proposed a possible mechanism for improving Na+ diffusion. The as-prepared P2-type layered oxide presents a quasi-hexagon shape and demonstrates a discharge capacity of 87 mAh g-1 at a current density of 875 mA g-1 (5 C rate), twice that of the sample synthesized from a non-nanoplate particle precursor. Rietveld refinement and results of X-ray photoelectron spectroscopy reveal the probable mechanism that the expanded interplanar spacing along the c-axis orientation would facilitate Na+ diffusion during Na+ intercalation/deintercalation processes, and the expanded interplanar spacing may arise from a high oxidation state of transition metal ions.

It should be a promising paradigm for graphene application in semiconductor industry by incorporating graphene into silicon to improve the behavior of silicon-based devices or develop high-performance devices with a new physical mechanism. Here we report on a large positive magnetoresistance (MR) over 80% at a magnetic field of 2.2 T and a temperature of 80 K in graphene/Si Schottky junctions by stacking chemical vapor deposition derived monolayer graphene on silicon. The produced MR is anisotropic and dependent on the angle between the direction of the magnetic field and the configuration plane, and can be modulated by the electrical bias across the configuration due to the built-in electric field. The MR effect should be ascribed to the charge carriers scattering and the released silicon magnetic moments in the graphene/Si interface that is suggested by first principles calculations. The study here should be helpful to understand the interface between the graphene and silicon, develop high-performance silicon based devices, complement the extraordinary properties of graphene and open one possible way to exploit their application for magneto-electronics. (C) 2017 Elsevier Ltd. All rights reserved.

Graphene/silicon heterostructures present a Schottky characteristic and have potential applications for solar cells and photodetectors. Here, we fabricated graphene/silicon heterostructures by using chemical vapor deposition derived graphene and n-type silicon, and studied the electronic and optoelectronic properties through varying their interface and silicon resistivity. The results exhibit that the properties of the fabricated configurations can be effectively modulated. The graphene/silicon heterostructures with a Si (111) interface and high resistivity show a better photovoltaic behavior and should be applied for high-performance photodetectors. With the combined atomic force microscopy and theoretical analysis, the possible origination is discussed. The work here should be helpful on exploring high-performance graphene/silicon photoelectronics.

In human being’s history, both the Iron Age and Silicon Age thrived after a matured massive processing technology was developed. Graphene is the most recent superior material which could potentially initialize another new material Age. However, while being exploited to its full extent, conventional processing methods fail to provide a link to today’s personalization tide. New technology should be ushered in. Three-dimensional (3D) printing fills the missing linkage between graphene materials and the digital mainstream. Their alliance could generate additional stream to push the graphene revolution into a new phase. Here we demonstrate for the first time, a graphene composite, with a graphene loading up to 5.6 wt%, can be 3D printable into computer-designed models. The composite’s linear thermal coefficient is below 75 ppm·°C−1 from room temperature to its glass transition temperature (Tg), which is crucial to build minute thermal stress during the printing process.

Research on van der Waals heterostructures based on stacked 2D atomic crystals is intense due to their prominent properties and potential applications for flexible transparent electronics and optoelectronics. Here, nonvolatile memory devices based on floating‐gate field‐effect transistors that are stacked with 2D materials are reported, where few‐layer black phosphorus acts as channel layer, hexagonal boron nitride as tunnel barrier layer, and MoS2 as charge trapping layer. Because of the ambipolar behavior of black phosphorus, electrons and holes can be stored in the MoS2 charge trapping layer. The heterostructures exhibit remarkable erase/program ratio and endurance performance, and can be developed for high‐performance type‐switching memories and reconfigurable inverter logic circuits, indicating that it is promising for application in memory devices completely based on 2D atomic crystals.

Photoinduced doping in graphene and its related heterostructures has drawn much interest as one of the possible ways to control the electronic properties of graphene. In this paper, we report that graphene/silicon (Gr/Si) heterostructures are an effective configuration for photoinduced doping in graphene. Raman spectroscopy, electrical and photoelectrical measurements are used to characterize the photoinduced doping effect. The results demonstrate that the graphene in the Gr/Si heterostructure is p-doped by light irradiation, and the doping effect can be controlled by varying the irradiation time. For the electrical properties of the Gr/Si Schottky junction, the photoinduced doping effect reduces the barrier height and series resistance but enhances the ideality factor. For the photovoltaic properties, the doping strengthens the open-circuit voltage, short-circuit current, fill factor, and conversion efficiency. The work should be helpful on developing effective ways for graphene doping and in depth understanding and better use of Gr/Si Schottky junctions for electronics and optoelectronics.

Heavy metal ( HM ) toxicity is a worldwide concern because it damages plants by altering their major physiological and metabolic processes. The heavy metal cadmium ( Cd) is a nonessential element, and is a valid inhibitor of plant growth. The toxic effect of cadmium is closely related to its transfer from the soil to the plant above ground parts. Understanding the transport pathway and regulatory mechanism of cadmium in plants may improve plant resistance to this heavy metal, in addition to providing a theoretical basis for the phytoremediation soils contaminated by cadmium. In this paper, we reviewed the transport pathways of Cd2+ in plants and what limits its mobility based on the cytological structural and molecular regulation mechanism of plants. As the main organ for transporting water and nutrients to the plant body, the plant root is also the main organ that absorbs toxic metals, such as cadmium. During the process of Cd2+ transfer from the root cortex to the xylem, most Cd2+is deposited between the cells of the root cortex, with some reaching stele, before being transferred to the plant organs, such as the leaves in the above ground part of the plant. The transport pathway of Cd2+through the root cortex is mainly apoplastic, with the cytoplasmic accumulation of Cd2+possibly causing apoplastic transport towards the vascular cylinder to decline. The transport pathway of Cd2+ in the vascular cylinder is also mostly apoplastic, with cytoplasmic accumulation reducing Cd2+ transfer to the xylem. Since the aboveground parts of plants are more susceptible to Cd2+ poisoning, two cellular strategies to restrict the absorption and transfer of cadmium have evolved. First, the Casparian strip surrounding radial wall and the endodermis wall prevents Cd2+ from entering the root xylem via the apoplastic pathway. In addition, the Casparian strip promotes Cd2+ transport via the endodermis, leading to vacuolar isolation and cytoplasmic precipitation. Second, heavy metal detoxification occurs by chelating Cd2+ to form stable compounds, which are then deposited inside the vacuole. Third, excess cadmium also activates oxidative stress defense mechanisms and the synthesis of heavy metal stress related proteins to minimize metal toxicity, which includes the use of metallothiones and ion channels, such as H+/Cd2+binding or sequestrating Cd2+into vacuoles. For systematic improvements in the phytoremediation of heavy metal pollution, a more comprehensive understanding of cellular mechanisms involved in Cd avoidance, uptake, transport, and accumulation is required. Furthermore, the excluder strategy by extensive sequestration and retranslocation of cadmium through symplastic and apoplastic pathways should be confirmed and explored in future studies.

The combination of semiconductor quantum dots (QDs) and graphene or graphene oxide is attracting much attention due to its unique properties and potential applications for optoelectronics or photocatalysts. Here a solution process is reported to firmly anchor zinc oxide QDs on the surface of graphene oxide by a covalent method. The graphene oxide is obtained with a modified Hummers method and slightly reduced and modified with hydrosulfide groups. Zinc oxide QDs are ultrasonically mixed with the modified graphene oxide and then anchored on the surface due to the strong interaction of Zn–S bond. The mixture is analyzed with transmission electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy in details. Further photoluminescence spectroscopy and photoelectrical characterizations exhibit that charge transfer happens between zinc oxide QDs and graphene oxide, indicating it should have potential applications for optoelectronics and photocatalysts.

Graphene/silicon (Gr/Si) configurations form Schottky junctions and should be a promising structure for high-performance electronics and optoelectronics. Here we presented a study on the properties of Gr/Si Schottky junctions by thermal annealing and air exposing. It was found that the ideal factor and the Schottky barrier height were lowered after vacuum annealing and increased after exposing in air for several days. The modulation of the Schottky junctions was further used to tune their optoelectronic properties. The results exhibit that the open-circuit voltage of the junctions under light illumination was varied with the ideal factor. The work here should be helpful on developing high-performance Gr/Si electronics and optoelectronics.

Graphene‐silicon based configurations are attracting great attention for their potential application as electronics and optoelectronics. For their practical use, it is still limited by the configuration fabrication process. In this paper, a catalyst‐free method is reported to directly grow nanographene on silicon covered with a thin oxide layer to form nanographene‐oxide‐silicon configurations. Compared with previously reported nanographene‐silicon Schottky junctions, the nanographene‐oxide‐silicon structures exhibit a high performance on electronic and photovoltaic properties. The reverse leakage current of the nanographene‐oxide‐silicon is suppressed from over 10−5 A down to 10−8 A and the rectifier ratio is greatly enhanced from less than 5 up to 103. The photovoltage is enhanced over 50 times. The nanographene‐oxide‐silicon structures exhibit especially ultrasensitive to weak light at a photovoltage working mode, which exceeds up to 106 V/W at the light power of 0.025 μW. Due to the source material for nanographene is photoresist and the fabrication process is mainly based on the current‐used photolithography and silicon technique, the developed nanographene‐oxide‐silicon structures are very easy for device fabrication, integration, and miniaturization, and could be a promising way to produce metal‐free graphene‐silicon based electronics and optoelectronics for commercial use.

Conventional methods to produce graphene/silicon Schottky junctions inevitably involve graphene transfer and metal deposition, which leads to the techniques being complicated, high‐cost, and environmentally unfriendly. It is possible to directly grow hybrid nanocrystalline graphene/graphite transparent electrodes from photoresist on quartz without any catalyst. Due to the source material being photoresist, nanographene/graphite patterns can easily be made on Si/SiO2 structures to form nanographene/silicon Schottky junctions via commercial photolithography and silicon techniques. The obtained Schottky junctions exhibit excellent properties with respect to photodetection, with photovoltage responsivity of 300 V W‐1 at a light power of 0.2 μW and photovoltage response time of less than 0.5 s. The devices also exhibit an excellent reliability with the photovoltage deviating less than 1% when cycled over 200 times.

Graphene nanoribbons have been widely studied for their potential applications in nanoelectronics. Recently, the discovery of producing graphene nanoribbons from chemically longitude-unzipped carbon nanotubes proposed one possible way to obtain graphene nanoribbons on large scale. Graphene oxide nanoribbons, as an intermediate product in this process, have interesting properties and are necessary to be studied. In this paper, we reported on the study of field-effect transistors based on single sheet of graphene oxide nanoribbons obtained from chemically longitude-unzipped carbon nanotubes. We found that the devices with different thicknesses from monolayer to over 20 layers all show semiconducting behaviors and ambipolar field-effect transistor properties. Combining X-ray photoelectron spectroscopy and Raman spectroscopy, the origination of the semiconducting behavior of the graphene oxide nanoribbons was discussed.

Catalyst-free growth of a nanocrystalline few-layer graphene (or graphite) film from photoresist on variable substrates was demonstrated. The thickness of the film can be easily controlled from 1 nm to hundreds of nanometers. With this method, graphene/graphite patterns with different thicknesses have been designed for integrated electronics.

In the thin-lens focal length measurement experiment,after using the improved LED flashlights as the new experimental optical sources,the effect is not only better than that of using the original incandescent light source,but also consistent with energy conservation,environmental protection,and low-carbon economy.

By analysis on clear image sections of screen and micrometer eyepiece in experiment to measure focal length of thin lens,replaced screen with micrometer eyepiece,improved measuring method,and reduced errors of experiments considerably.