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Hard carbon is promising anode for potassium-ion batteries (PIBs), however, the poor rate capability hinders its development as potential anode. To address this question, we design a sulfur-doped porous hard carbon (S-HC) for PIBs through the combination of structural design and composition adjustment. The as-designed S-HC exhibits a long cycling life with ∼191 mA h/g after 300 cycles at 1 A/g, and an excellent rate capability with ∼100 mA h/g at 5 A/g, which was attributed to its structural characteristics and compositions. The S-HC demonstrates to be promising anode in the future.

Low open-circuit photovoltage and poor hole transfer character of semiconductors have limited the development of p-type dye-sensitized solar cells (p-DSSCs) owing to the minor energy-gap between the conduction band of NiO and the Nernstian potential of the I3−/I− electrolyte, as well as the low intrinsic hole-conductivity of NiO semiconductor. Hereby, a novel NiO/CuO nanocomposite was well-designed and successfully fabricated as photocathode material of p-DSSCs. Combined with Co2+/Co3+ electrolyte, the devices showed noticeable enhancement of both open-circuit photovoltage and short-circuit photocurrent. Compared to NiO, a deeper valence-band of NiO/CuO resulted in a 140 mV improvement of photovoltage of p-DSSCs. Electrochemical impedance spectroscopy indiates an improved hole transport of NiO/CuO nanocomposite due to modified effect by CuO. Charge recombinations are also suppressed to achieve increased charge collection efficiencies and improved photoelectrochemical performance.

One-dimensional nano-structured materials have attracted attention due to its unique properties afforded such as the across-linked structures and large aspect ratios. In this work, one-dimensional CoSe@N-doped carbon nanofibers (CoSe@NC NFs) are successfully by combining the techniques of electrospinning and annealing. Selenium powder are directly dispersed in the polyacrylonitrile /N,N-Dimethylformamide (DMF) solution containing cobalt salt to form the product. The performance of these materials was investigated in Li-ion batteries after the annealing at different temperatures. The CoSe@NC nanofibers annealed at 550 °C (CoSe@NC-550) and displayed excellent storage properties, affording a high capacity of 796 mAh·g−1 at a current density of 1 A·g−1 for 100 cycles. Moreover, it is confirmed that the pseudocapacitive contribution of CoSe@NC-550 is up to 72.8% at the scan rate of 1 mV/s through the cyclic voltammetry analysis.

As a promising material for sodium-ion batteries, molybdenum disulphide (MoS2) affords excellent electrochemical performance owing to its large surface area and the accelerated electron transport within individual layers. However, it suffers from slow reaction kinetics and agglomeration owing to low conductivity and high surface energy. In this work, nitrogen-doped carbon nanofiber@MoS2 nanosheets arrays with S-vacancies (NC@MoS2-VS) are developed via a process involving electrospining, hydrothermal and annealing. When served as an anode material for SIBs, this material displays a superior capacity of 495 mAh g−1 over 100 charge/discharge cycles at a current density of 100 mA g−1, and the pseudocapacitive contribution is up to 74.4% as revealed by the cyclic voltammogram (CV) at 1 mV s−1. The theoretical calculations show that the presence of sulfur vacancies facilitates the adsorption of Na+ and enhances the conductivity of MoS2. This work may pave a new avenue to develop other types of metal sulfides for high-performance SIBs.

The NASICON-type NaTi2(PO4)3 has drawn much attention as anode material for sodium-ion batteries owing to its stable structural characteristics and low cost. Nevertheless, the insulating property of NaTi2(PO4)3 and the high working potential of about 2.1 V vs. Na+/Na lead to its poor cycling stability, low rate performance as well as inferior capacity. In this work, we synthesize the porous NaTi2(PO4)3@C nanocubes by hydrothermal method and a subsequent coating process with using oleic acid as the carbon source. When utilized as the anode for sodium-ion battery in the voltage range between 0.01 V and 3.0 V, The as-synthesized porous NaTi2(PO4)3@C nanocubes deliver a discharge capacity of 201 mAh·g−1 at the current density of 100 mA g−1 after 100 cycles. Additionally, the reserved capacity of 140 mAh·g−1 could be achieved at the current density of 1 A g−1 after 1000 cycles.

MoO2@N-doped C nanofibers (MoO2@NC NFs) were synthesized by electrospinning with polyacrylonitrile as carbon source. The in situ formed MoO2 nanocrystals are completely embedded in the carbon nanofibers, which can not only accelerate ion transition, but also act as a buffer to avoid the mechanical degradation of active material due to the volume changes during charge/discharge cycling. When used as the anode material for both Li/Na-ion batteries, the as-synthesized MoO2@NC NFs displayed excellent Li+/Na+ storage properties. As the anode for Li-ion battery, the MoO2@NC NFs display a high discharge capacity of 930 mA h g−1 at a current density of 200 mA g−1 for 100 cycles, and 720 mA h g−1 at a current density of 1 A g−1 for 600 cycles. Moreover, the discharge capacity of 350 mA h g−1 could be realized at a current density of 100 mA g−1 for 200 cycles for Na-ion battery.

MnO@C nanocomposites are synthesized by annealing MnO microspheres treated with oleic acid as carbon source. The obtained MnO@C nanocomposites exhibit a discharge capacity of 1075 mAh/g for the initial cycle, and show the excellent cycling performance with a discharge capacity of 421 mAh/g after 100 cycles at a current density of 100 mA/g. The total specific capacity of MnO@C nanocomposites is higher than those of pure MnO microspheres in our experiments. Owing to the superior electrochemical behavior, the as-obtained MnO@C nanocomposites are potentially applied as next-generation anode material for lithium-ion batteries.

A Weyl semimetal can be considered as a system composed of two Weyl cones breaking time-reversal symmetry, which exhibits strong anisotropic hyperbolic characteristics. The off diagonal components of the permittivity tensor of a Weyl semimetal produce the Faraday and Kerr effects. In this paper, we investigate the Goos–Hanchen (GH) shifts when a light is reflected from the interface of air and a Weyl semimetal. It is demonstrated that the angular GH shift is still tiny; however, the spatial GH shift can be huge and is very sensitive to change in the incident angle. The spatial GH shift can change from positive to negative with an increase in the incident angle. The spatial GH shifts vary at different distances of two Weyl cones and thicknesses of a Weyl semimetal film. Furthermore, the tunable GH shift can be realized by changing the tilting parameter and Fermi energy. These adjustable and giant GH shifts may find practical applications in optical shift devices and optical sensors.

Uniform Co3O4–SnO2 nanoboxes have been synthesized successfully by a facile annealing treatment. Their hollow and cubic structure can be retained successfully during calcination. Due to their hollow structure and PN junction, these Co3O4–SnO2 nanobox sensors can detect H2S with high sensitivity at a low temperature of 180 °C. In addition, it was found that the Co3O4–SnO2 nanobox sensors obtained at a higher annealing temperature displayed a higher sensitivity and lower recovery time to H2S in a temperature range of 500 to 700 °C. X-ray photoelectron spectroscopy (XPS) was employed to confirm that the changes in resistance and the high sensitivities of the sensors are significantly attributable to the transformation of Co3O4 to CoSx with high conductivity under an H2S atmosphere.

A three-dimensional flower-shaped iron molybdate microsphere (3D-FIMMS) and a zero-dimensional iron molybdate nanoparticle (0D-IMNP) were successfully synthesized by a rapid and environment friendly microwave irradiation method. The 3D-FIMMS crystal growth was investigated by changing the microwave heating time. The gas sensing performances of various morphologies of iron molybdate were studied. The results showed that 3D-FIMMS sensors exhibited excellent gas sensing properties compared with the 0D-IMNP sensors, in which response value reached 13.5 for 50 ppm H 2 S gas. Meanwhile, the 3D-FIMMS sensors displayed high selectivity to H 2 S. The experimental results indicated an efficient and eco-friendly approach to realize promising sensing performance to H 2 S gas.

NaTi2(PO4)3 has attracted great interest as anode material for sodium ion batteries owing to its open three-dimensional framework structure and almost unchanged volume during the charge and discharge process. However, the poor intrinsic electronic conductivity of NaTi2(PO4)3 still needs to be improved. In this work, porous NaTi2(PO4)3 nanocubes anchored on porous carbon nanosheets (NaTi2(PO4)3/C) are designed to improve the electrical conductivity. This material exhibit a large discharge capacity and good rate capacity: The first discharge capacity can reach 485 mAh g-1 at a current density of 0.1 A g-1; A capacity of 98 mAh g-1 can be retained at a high rate of 4 A g-1 even after 2,000 cycles. These results suggest that NaTi2(PO4)3/C is a promising anode material for sodium-ion batteries.

It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO2 nanoflowers (NC@SnO2) to overcome it in this work. The hybrid NC@SnO2 is synthesized through the hydrothermal growth of SnO2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO2 was served as anode, it exhibits a high discharge capacity of 750 mAh g−1 at 1 A g−1 after 100 cycles in Li-ion battery and 270 mAh g−1 at 100 mA g−1 for 100 cycles in Na-ion battery, respectively. Electronic supplementary material The online version of this article (10.1007/s40820-017-0172-2) contains supplementary material, which is available to authorized users.