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Heterostructures have broad potential application in energy conversion material and optoelectronic device since of novel interface effect and enhanced electron transport dynamics at heterointerfaces. Herein, we report a heterostructured SnS/SnO2/spherical graphene composite, in which ultrafine SnS/SnO2 nanoparticles with heterostructures are sandwiched between multi-layers of graphene sheets, exhibiting a hollow spherical architecture as a whole. Detailed electrochemical studies indicate that the molar ratio of SnS to SnO2 has great influence on the charge transport efficiency. Theoretical calculation reveals that SnS and SnO2 exhibit different work functions and the Fermi level shift is affected by the SnS/SnO2 molar ratio, thus the hybrid with the ratio close to 1.0 owns the most adsorbed lithium ions, which leads to the highest specific charge-transfer kinetics and lowest ion-diffusion resistance than other samples. Electrochemical tests show that the composite with appropriate composition delivers the best lithium storage rate performance (620 and 312.7 mAh g−1 at 1 C and 10 C). A much stable and high reversible specific capacity of 850 mAh g−1 is obtained after 200 cycles at 0.1 C. The appropriate molar ratio of nano-heterostructures and the novel sandwich hollow spherical composite structure are attributed to the excellent electrochemical performances.

Efficient electrocatalysts for hydrogen evolution reaction (HER) are critical to reduce energy losses in alkaline water electrolysis. Herein, CoNiSe2 heteronanorods decorated with layered-double-hydroxides (LDHs) nanosheets are designed, in which the selenide-LDHs interfaces can boost H2O chemisorption to produce reactive H intermediate, resulting in fast HER kinetics. Such promotion in HER is further interpreted by theoretical calculation and in-situ Raman investigation. By contrast, it’s negligible for anodic oxygen evolution. Assembled as an electrolyzer for overall water splitting, the heteronanorods afford a quite low cell voltage of 1.44 V at a geometric current density of 10 mA cm−2 and remarkable stability for more than 48 h in 1.0 M KOH, performing among the best of non-precious electrocatalysts. Identifying efficient electrocatalysis on engineered heterointerfaces, this work is anticipated to open up new opportunities for catalyst design in energy chemistry.

The reunion of Sn is always a troublesome issue when it’s used as the energy storage materials, on the one hand it comes from the preparation process due to its low melting point, and on the other hand it comes from the Li-Sn alloying process because of its natural tendency of migration. The Sn/SnO2/spherical graphene composite prepared by one-step low temperature hydrothermal reduction method can effectively solve this problem. In the composite, Sn/SnO2 tiny nanoparticles with average diameter of 5 nm distribute evenly between multilayers of graphene sheets presenting a hollow spherical structure. The introduction of SnO2 can effectively restrain the agglomeration of Sn nanoparticles during alloying process since an amorphous Li2O matrix is formed to separate the adjacent active particles. The sandwich graphene hollow sphere skeleton effectively buffers the volume expansion of Sn/SnO2 and further restricts their migration and agglomeration. Due to the above advantages, the nano-Li2O generating from the decomposition of SnO2 can contact closely with excessive nano-Sn in restricted area, promoting facile conversed conversion reaction. Therefore, the composite exhibits high reversible capacity and excellent cycle performance. A stable and high specific capacity of 843.8 mAh g−1 is obtained after 100 cycles at 0.1 C.

SnS is widely studied as anode materials since of its superior structural stability and physicochemical property comparing with other Sn-based composites. Nevertheless, the inconvenience of phase morphology control and excessive consumption of sulfur sources during synthesis hinder the scalable application of SnS nanocomposites. Herein, we report a facile in-situ sulfuration strategy to synthesize sandwiched spherical SnS/sulfur-doped graphene (SnS/S-SG) composite. An ultra-low sulfur content with approximately stoichiometric ratio of Sn:S can effectively promote the sulfuration reaction of SnO2 to SnS and simultaneous sulfur-doping of graphene. The as-prepared SnS/S-SG composite shows a three-dimensional interconnected spherical structure as a whole, in which SnS nanoparticles are sandwiched between the multilayers of graphene sheets forming a hollow sphere. The sandwiched sphere structure and high S doping amount can improve the binding force between SnS and graphene, as well as the structural stability and electrical conductivity of the composite. Thus, a high reversibility of conversion reaction, promising specific capacity (772 mAh g−1 after 100 cycles at 0.1 C) and excellent rate performance (705 and 411 mAh g−1 at 1 C and 10 C, respectively) are exhibited in the SnS/S-SG electrode, which are much higher than that of the SnS/spherical graphene synthesized by traditional post-sulfuration method.

Lithium sulfide as a promising cathode material not only have a high theoretical specific capacity, but also can be paired with Li-free anode material to avoid potential safety issues. However, how to prepare high electrochemical performance material is still challenge. Herein, we present a facile way to obtain high crystal quality Li 2 S nanomaterials with average particle size of about 55 nm and coated with Li 3 PS 4 to form the nano-scaled core-shell Li 2 S@Li 3 PS 4 composite. Then nano-Li 2 S@Li 3 PS 4 /graphene aerogel is prepared by a simple liquid infiltration-evaporation coating process and used directly as a composite cathode without metal substrate for lithium-sulfur batteries. Electrochemical tests demonstrate that the composite delivers a high discharge capacity of 934.4 mAh g −1 in the initial cycle and retains 485.5 mAh g −1 after 100 cycles at 0.1 C rate. In addition, the composite exhibits much lower potential barrier (∼2.40 V) and overpotential compared with previous reports, indicating that Li 2 S needs only a little energy to be activated. The excellent electrochemical performances could be attributed to the tiny particle size of Li 2 S and the superionic conducting Li 3 PS 4 coating layer, which can shorten Li-ion and electron diffusion paths, improve the ionic conductivity, as well as retarding polysulfides dissolution into the electrolyte to some extent.

Exploring noble-metal-free electrocatalysts with high efficiency for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) holds promise for advancing the production of H2 fuel through water splitting. Herein, one-pot synthesis was introduced for MoS2–Ni3S2 heteronanorods supported by Ni foam (MoS2–Ni3S2 HNRs/NF), in which the Ni3S2 nanorods were hierarchically integrated with MoS2 nanosheets. The hierarchical MoS2–Ni3S2 heteronanorods allow not only the good exposure of highly active heterointerfaces but also the facilitated charge transport along Ni3S2 nanorods anchored on conducting nickel foam, accomplishing the promoted kinetics and activity for HER, OER, and overall water splitting. The optimal MoS2–Ni3S2 HNRs/NF presents low overpotentials (η10) of 98 and 249 mV to reach a current density of 10 mA cm–2 in 1.0 M KOH for HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, such heteronanorods show a quite low cell voltage of 1.50 V at 10 mA...

Three-dimensional (3D) interconnected spherical graphene framework-decorated SnS nanoparticles (3D SnS@SG) is synthesized by self-assembly of graphene oxide nanosheets and positively charged polystyrene/SnO2 nanospheres, followed by a controllable in situ sulfidation reaction during calcination. The SnS nanoparticles with diameters of ∼10–30 nm are anchored to the surface of the spherical graphene wall tightly and uniformly. Benefiting from the 3D interconnected spherical graphene framework and subtle SnS nanoparticles, the generated Li2S could keep in close contact with Sn to make possible the in situ conversion reaction SnS + 2Li+ + 2e– ↔ Sn + Li2S. As a result, the 3D SnS@SG as the anode material for lithium ion batteries shows a high initial Coulombic efficiency of 75.3%. Apart from the irreversible capacity loss of 3D spherical graphene, the initial Coulombic efficiency of SnS in the 3D SnS@SG composite is as high as 99.7%, demonstrating the almost complete reversibility of Li2S in this system. Furth...

As one of the key components of Sector Focusing Cyclotron at the Institute of Modern Physics, Chinese Academy of Sciences, the electrostatic deflector can be activated by primary and secondary particles, because of a mismatch between the actual value and the design value of the emittance and emergence angle. In addition, it will be struck by more particles, since there is a stray magnetic field and outgas from the surface of the electrostatic deflector. The residual radioactivity in the electrostatic deflector has been studied in two aspects: specific activity and residual dose rate, based on the gamma-ray spectrometry and Fluke 451p ionization chamber, respectively. The specific activity of radionuclides in the main components and the dust on the enclosure have been investigated by using gamma-ray spectrometry. The residual dose rate around the electrostatic deflector has been obtained by Fluke 451p ionization chamber. The results of the study show that there is a non-negligible radiological risk to the staff. This result can be provided as guidance for making a maintenance schedule, so that the dose received by staff can be kept as low as reasonably achievable. Based on the results, advice for "hands-on" maintenance and decommissioning of the SFC have been provided.

The evolution of products of tire powders, with special attention to the yields and composition over time under microwave pyrolysis, was studied. The solid, liquid, and gaseous products generated were all collected separately during the pyrolysis process and characterized. In addition, temperature was measured using a thin thermocouple intermittently. The sample temperature first rose, then fell, and finally stabilized at approximately 500 °C. The major components of the pyrolysis gases were H2, CH4, and C2H4. The liquid products were complex mixtures of organic compounds with large proportions of aromatics and limonene. The solid residues, with high contents of carbon black and S, pyrolyzed almost completely at 20 min, and the samples in the center of the reactor were pyrolyzed earlier than those in the surrounding areas were. At the end of the pyrolysis, 43% of the solid residues, 45% of the oils, and 12% of the pyrolysis gases were obtained.

Heavy ion medical machine (HIMM) is built by the Institute of Modern Physics, Chinese Academy of Sciences, with a high-energy beam transport line with a height of 18 m, and its complex space mounting structure increases the difficulty of installation and alignment. The aim of this paper is to provide methods to install all accelerator components efficiently and to ensure that the alignment accuracies of all installed components are within the designed values. We accomplished the fiducialization and pre-alignment of complex modules by combining the laser tracker and the alignment telescope. By analyzing various elements that affect the accuracy of alignment, a method of alignment for high-energy beam transport line was proposed based on high-precision three-dimensional control network. All components have been installed and aligned in a short time, alignment position accuracy of magnets is less than 0.1 mm, and the treatment components alignment accuracy is no more than 0.4 mm. On the basis of error analysis, all alignment results are better than the required precisions, and all of these guaranteed the successful operation of HIMM.

Ultrathin, undersized MoS2/graphene composites are fabricated by a facile acetic acid assisted hydrothermal route and post-annealing. The structure and morphology characterization reveals that the MoS2 nanosheets with ∼5 layers and 130–160 nm in size are decorated on the surface of graphene nanosheets homogeneously and tightly. The effects of acetic acid and N-methyl-pyrrolidone solvent on the microstructures and electrochemical performances of the MoS2/graphene composites are investigated. It is found that the acetic acid could maintain a constant pH and promote hydrolysis of thiourea, and thus many more MoS2 crystals nucleus were formed, while the N-methyl-pyrrolidone could inhibit the aggregation of the as-prepared MoS2 sheets, and therefore few-layered MoS2 sheets with a small size are obtained. Electrochemical tests confirmed that the lithium storage performance of ultrathin, undersized MoS2/graphene is greatly improved compared to that without addition of acetic acid or N-methyl-pyrrolidone solvent. A high reversible capacity of 1229 mA h g−1 is achieved in the initial cycle and is maintained at 942.6 mA h g−1 after 50 cycles at a current density of 100 mA g−1. Even at a current density of 1000 mA g−1, the reversible capacity could be maintained as high as 747 mA h g−1.

Rational design of composite with other electroactive materials can effectively improve the supercapacitive performances through the modulation of electronic structure and conductivity of the hybrid material. In this work, core-shell structured Ni3S2@VO2 nanorods on the nickel foam are prepared through a one-pot hydrothermal method. The addition of VO2 effectively reduces the charge transfer resistance and thus enhances the electrochemical conductivity. The nickel foam provides a platform for the in situ dispersive growth of Ni3S2@VO2 as well as a “superhighway” for the transformation of electrons. The Ni3S2@VO2 shows a high areal specific capacity of 1.09 C cm−2 at 1 mA cm−2. After a slight decrease in the initial 200 cycles, the discharge capacity remains almost constant at about 1.00 C cm−2 during the following cycles. At a high current of 50 mA cm−2, the areal specific capacitance is 0.09 C cm−2. A symmetric supercapacitor is assembled using Ni3S2@VO2 as both the anode and cathode. The specific capacity of it is 0.864 C cm−2 at a current of 1 mA cm−2. Good cycling stability and rate capability are also obtained. All these features promise it a high performance supercapacitor electrode.

The new injector SSC-LINAC is under design and construction to improve the efficiency and intensity of beams for the Separated-Sector Cyclotron (SSC). This will be accomplished with a normal conducting radio-frequency quadrupole (RFQ) accelerator. To match with the SSC, the RFQ must be operated on Continuous Wave (CW) mode with a frequency of 53.667 MHz. A four-rod structure was adopted for small dimensions of the cavity. While, it was a huge challenge on CW mode. A multi-physics theoretical analysis, including RF, thermal, structural and frequency shift coupling analysis, have been completed in response to the safe and stable operation of the RFQ. The experimental measurement of frequency shift has been also completed, which is consistent with the simulation. In this paper, the results of theoretical analysis and experiment are reported in detail.

The SSC-LINAC project is launched at Institute of Modern Physics in China to develop one new linear accelerator (LINAC) injector for separated sector cyclotron (SSC). It includes a high charge state ion source, a CW RFQ and a DTL section, and is designed to accelerate ions up to 580 keV/u. Now the ion source and the RFQ cavity have been installed in the main hall and the beam commissioning has been carried out. Two kinds of ions have been tested, 16 O 5+ and 40 Ar 8+ . The experiment result of 16 O 5+ is: the measured beam current is 180 μA at entrance of RFQ and 150 μA at exit of RFQ. The output energy of 16 O 5+ is 141.89 keV/u. The measured beam current is 210 μA at entrance of RFQ and 198 μA at exit of RFQ for 40 Ar 8+ . The output energy of 40 Ar 8+ is 142.78 keV/u. The experiment results agree with the design parameters of RFQ very well. This paper presents: the design consideration of beam dynamics, RF and cooling structure design; measurement of the cold model; high power test of RFQ and beam commissioning result.

The new linac injector SSC-LINAC has been proposed to replace the existing Separator Sector Cyclotron (SSC). This effort is to improve the beam efficiency of the Heavy Ion Research Facility of Lanzhou (HIRFL). As a key component of the linac, a continuous-wave (CW) mode high charge state heavy ion radio-frequency quadrupole (RFQ) accelerator has been designed. It accelerates ions with the ratio of mass to charge up to 7 from 3.728 keV/u to 143 keV/u. The requirements of CW mode operation and the transportation of intense beam have been considered as the greatest challenges. The design is based on 238U34+ beams, whose current is 0.5 pmA (0.5 particle mili-ampere, which is the measured 17 emA electric current divided by charge state of heavy ions). It achieves the transmission efficiency of 94% with 2508.46 mm long vanes in simulation. To improve the transmission efficiency and quality of the beams, the phase advance has been taken into account to analyze the reasons of beam loss and emittance growth. Parametric resonance and beam mismatch have been carefully avoided by adjusting the structure parameters. The parameter-sensitivity of the design is checked by transportation simulations of various input beams. To verify the applicability of machining, the effects of different vane manufacturing methods on beam dynamics are presented in this paper.