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Post cobalt doped NbSSe was synthesized by combining chemical vapor transport and the hydrothermal method, which exhibited excellent HER performance due to the synergistic effect of cobalt doping and S/Se vacancies.

The NM2.7Mg0.3PP@C cathode displays a considerable discharge capacity, an improved rate capability, superior cycling performance and stable structure.

Two interfaces formed after carbothermal reduction reaction was investigated by transmission electron microscopy and invariant line calculation. The crystallographic features of the two phase transition system have been successfully interpreted.

Four binary organic charge transfer cocrystals were grown by the slow cooling method. The competitive role of C–H⋯X (X = F, O) and π–π interactions in contributing to the degree of charge transfer in the cocrystals was investigated.

A defect-type AlOx nanointerface containing Al2+ has been constructed on the surface of NaMn0.6Al0.4O2 by surface segregation and reconstruction, which exhibits excellent Na-storage performance as the cathode of SIBs over a wide temperature range.

Few-layer Mg-deficient borophene nanosheets with a stoichiometric ratio Mg0.22B2 are prepared by oxidizing with I2 and delaminating from MgB2. The flakes have Mg atom deintercalation rate of 78% while maintaining the hexagonal structure of boron.

SnS2 nanowall-based PEC-type photodetectors show the highest photoresponsivity of 1460 μA W−1 prepared by a facile hydrothermal approach, which also have a fast response time and excellent stability.

The Ti

Organic semiconductors have been receiving intensive attention due to the specific advantages of low‐temperature processing ability, low‐fabrication cost, flexibility, and so forth. The charge carrier mobility of higher than 10 cm2 V−1 s−1 for organic semiconductors is of great importance to be studied since it presents a future promising research direction toward commercial microelectronic applications. With the significant progress of the discovery of novel organic molecules and the further improvements of device fabrication technology, some organic molecules can break the limit of our knowledge and show very high mobilities. In this review, organic polymers and small molecules with mobilities above 10 cm2 V−1 s−1 are first introduced to provide the readers with a general understanding of the features and characteristics of high‐performance organic semiconductors. Then, some important parameters, including the molecular structures, the device configurations, and the performance, are discussed in detail. Finally, the clues to obtain high mobility are summarized, and the perspective toward the future possible research directions are also provided.

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O2 batteries. Herein, a novel bifunctional photo-assisted Li-O2 system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O2 batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O2 batteries exhibits a high rate (129 % round-trip efficiency at 1 mA cm-2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g-1 at 0.75 mA cm-2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.

As a conductive polymer with great potential, poly(3,4-ethylenedioxythiophene) (PEDOT) has been developed as a high-rate supercapacitor electrode but stores less energy due to its limited theoretic...

By employing a carbon nanotube (CNT) sponge with a 3D porous network as a compressible substrate and NiCo2S4 nanoparticles as active materials, a NiCo2S4/CNT sponge electrode with high compression ...

Surface modification is an effective strategy to promote charge transport and extraction, reduce the carrier recombination probability, and ultimately improve the performance of perovskite solar cells (PSCs). Borophene is the lightest two-dimensional (2D) layered material, with high carrier mobility and high hardness. In this work, a sonication-assisted liquid-phase preparation technique was developed to prepare borophene quantum dots (BQDs) with uniform size, good dispersion, and high stability. The use of BQDs as a surface passivation agent on the TiO2 layer in an inorganic CsPbI2Br solar cell was presented. It is found that the boron atoms undergo strong interactions with TiO2 and the perovskite, reducing interfacial recombination and forming a cascade energy alignment for effective charge transport. A CsPbI2Br solar cell with a thin BQD interlayer shows high efficiency of 15.31%, whereas the efficiency was 14.24% for the device with no BQDs. The enhancement in efficiency is mainly due to carrier recombination suppression and a decrease in the defect density at the TiO2/CsPbI2Br interface after BDQ treatment. This work demonstrates that high-quality BQDs have great potential to be applied in perovskite solar cells and other optoelectronic devices.

In order to increase the capacity and improve the sluggish Na+-reaction kinetics of anodes as sodium ion capacitors (SICs), a Ti2Nb2O9/CNF self-standing film electrode comprised of Ti2Nb2O9 nanosheets and carbon nanofibers has been fabricated via electrospinning HTiNbO5 nanosheets with PAN and subsequent carbonization treatment. The as-prepared Ti2Nb2O9/CNF film electrode possesses fast Na-ion intercalation kinetics and high conductivity during Na-ion storage, and it displays a high reversible capacity of 324 mA h g−1 at 0.1 A g−1. Additionally, it also delivers a superior rate capability of 204 mA h g−1 at a high current density of 4 A g−1, as well as an excellent cycling stability of 97% retention after 2000 cycles at 1 A g−1 in a half-cell test. A prototype Ti2Nb2O9/CNF//AC SIC full device was assembled by employing the presodiated Ti2Nb2O9/CNF anode and AC cathode, and it exhibits an high energy density of 129 W h kg−1 at a power density of 75 W kg−1 and a high power density (7560 W kg−1 with 63 W h kg−1), a good cycling performance of 85% capacitance retention after 10 000 cycles at 1 A g−1, suggesting that the Ti2Nb2O9/CNF electrode with excellent performance would be a very promising candidate as the anode for high-performance SICs.

For the disadvantages of both the slow reaction kinetics and the poor conductivity for Nb2O5 electrode materials as sodium-ion capacitors (SICs), Nb2O5 NRs/NMMCNF film electrode with good flexibility and high electrochemical property has been fabricated by electrospinning PAN/PMMA/H2Nb2O6·H2O homogeneous viscous suspension and followed by an annealing treatment, in which the precursor H2Nb2O6·H2O nanorods are obtained by grinding H2Nb2O6·H2O nanowires, and Nb2O5 nanorods are uniformly embedded in nitrogen doped microporous multichannel carbon nanofiber. Benefiting from the multichannel network structure, Nb2O5 NRs/NMMCNF film electrode delivers the fast kinetics of Na+-storage and the superior Na-ion storage performance, it delivers outstanding rate capability (101 mAh g−1 at 4 A g−1) and ultralong lifespan (91% capacity retention after 10,000 cycles at 2 A g−1). A Nb2O5 NRs/NMMCNF//AC SIC based on the Nb2O5 NRs@NMMCNF fiber film anode and the AC cathode is assembled. The energy density of the as-assembled device is as high as 91 Wh kg−1 and its maximum power density is 7499 W kg−1. This work offers a new structure design strategy toward intercalation-type metal oxide electrodes for application in SICs.

Integration of conductive polymers with flexible substrate to construct an electronically conductive and mechanically flexible electrode is of great significance for a flexible energy storage devic...

By using Ti3C2Tx quantum dots as interlayer spacers, Ti3C2Tx nanosheets/Ti3C2Tx quantum dots/RGO (reduced graphene oxide) fiber (M6M3RG1) is prepared by a wet-spinning method; it shows good capacit...

Lithium sulfur batteries are expected to be one of the most promising energy storage systems due to their high energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides severely hampers their practical application. The design of the sulfur cathode is one of the most important approaches to overcome the problem. In this work, MoS2 nanosheets have been successfully grown on the surface of hollow carbon spheres (HCS) to obtain MoS2@HCS nanocomposites with uniform morphology. The growth behavior of MoS2 nanosheets was also proved by adjusting the pore structure of HCS. With a sulfur loading of 74%, the MoS2@HCS/S cathode exhibits a high initial reversible capacity of 1419 mA h g-1 at a current density of 0.1 C and remains at 1010 mA h g-1 after 100 cycles. Even at 0.5 C, a capacity of 795 mA h g-1 can be retained after 600 cycles, corresponding to a capacity retention rate of 63.1%. By adjusting the concentration of the sulfur source, the relationship between different growth quantities of MoS2 and the cycling performance of the battery was also investigated. The excellent electrochemical performance of the MoS2@HCS/S cathode can be fully attributed to its physical and chemical double adsorption effect on lithium polysulfides, which has been confirmed through the visible adsorption and X-ray Photoelectron Spectroscopy (XPS) experiments. This work provides a simple design concept and method to synthesize a nanocomposite-based sulfur host for high performance lithium sulfur batteries.

The intercalation and delamination processes of Ti3C2Tx are systematically investigated by using alkylammonium hydroxides (TAAOH) with different chain lengths. TAA+ cations have a key function for the intercalation reaction of Ti3C2Tx nanosheets, and the basal spacing and the crystal phase of TAA+-intercalated Ti3C2Tx at different stages are closely related to the size of the intercalated TAA+ ions, and they are hardly changed with the addition of molar equivalents of TAAOH per mole of Ti3C2Tx and the drying conditions. Moreover, the intercalation process is very rapid and it can be carried out by just 4 h treatment. TAA+-intercalated Ti3C2Tx can be delaminated into Ti3C2Tx nanosheets by hand shaking or repeated washing. By introducing a graphene oxide nanosheet suspension into the Ti3C2Tx nanosheet suspension, Ti3C2Tx/RGO fibers are firstly prepared by a wet-spinning method followed by reducing Ti3C2Tx/GO fibers in HI/CH3COOH solution. Then the Ti3C2Tx/RGO fiber is soaked in KMnO4 solution with different concentrations at room temperature, and a MnO2/Ti3C2Tx/RGO ternary hybrid fiber with good flexibility and capacitance is prepared. The MnO2/Ti3C2Tx/RGO ternary hybrid fiber electrode shows the largest volumetric capacitance of 851 F cm−3 in 1 M Na2SO4 electrolyte and good flexibility. By twisting two of these fiber electrodes together, an all-solid-state symmetric MnO2/Ti3C2Tx/RGO//MnO2/Ti3C2Tx/RGO fiber supercapacitor with PVA–LiCl gel electrolyte is assembled. It not only exhibits a volumetric capacitance of 24 F cm−3 and superior cycle stability of 92% after 10 000 cycles, but also shows outstanding flexibility and mechanical properties in which the volumetric capacitance has no obvious change after bending the supercapacitor at 90° 1000 times. Furthermore, the assembled symmetric supercapacitor shows the maximum volumetric energy density of 2.13 mW h cm−3 at a volumetric power density of 8.16 mW cm−3. This work will open a new application field of Ti3C2Tx-based fibers for new wearable energy storage devices with good energy density and flexibility.

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O

Lithium sulfur batteries are expected to be one of the most promising energy storage systems due to their high energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides severely hampers their practical application. The design of the sulfur cathode is one of the most important approaches to overcome the problem. In this work, MoS2 nanosheets have been successfully grown on the surface of hollow carbon spheres (HCS) to obtain MoS2@HCS nanocomposites with uniform morphology. The growth behavior of MoS2 nanosheets was also proved by adjusting the pore structure of HCS. With a sulfur loading of 74%, the MoS2@HCS/S cathode exhibits a high initial reversible capacity of 1419 mA h g-1 at a current density of 0.1 C and remains at 1010 mA h g-1 after 100 cycles. Even at 0.5 C, a capacity of 795 mA h g-1 can be retained after 600 cycles, corresponding to a capacity retention rate of 63.1%. By adjusting the concentration of the sulfur source, the relationship between different growth quantities of MoS2 and the cycling performance of the battery was also investigated. The excellent electrochemical performance of the MoS2@HCS/S cathode can be fully attributed to its physical and chemical double adsorption effect on lithium polysulfides, which has been confirmed through the visible adsorption and X-ray Photoelectron Spectroscopy (XPS) experiments. This work provides a simple design concept and method to synthesize a nanocomposite-based sulfur host for high performance lithium sulfur batteries.

Development of highly stabilized and reversible cathode materials has become a great challenge for sodium-ion batteries. O'3-type layered Mn-based oxides have deserved much attention as one of largely reversible-capacity cathodes featured by the resource-rich and low-toxic elements. However, the fragile slabs structure of typical layered oxides, low Mn-ion migration barriers, and Jahn-Teller distortion of Mn3+ have easily resulted in the severe degradation of cyclability and rate performances. Herein, a new queue-ordered superstructure is built up in the O'3-NaMn0.6 Al0.4 O2 cathode material. Through the light-metal Al substitution in O'3-NaMnO2 , the MnO6 and AlO6 octahedrons display the queue-ordered arrangements in the transition metal (TM) slabs. Interestingly, the presence of this superstructure can strengthen the layered structure, reduce the influence from Jahn-Teller effect, and suppress the TM-ions migrations during long-terms cycles. These characteristics results in O'3-NaMn0.6 Al0.4 O2 cathode deliver a high capacity of 160 mAh g-1 , an enhanced rate capability and the excellent cycling performance. This research strategy can provide the broaden insight for future electrode materials with high-performance sodium-ions storage.

The preparation of two-dimensional boron (B) nanosheets, especially for borophene, is still a challenge because of its unique structure and complex B–B bonds in bulk boron. In the present work, a novel preparation technology for borophene with only a few layers and large flake sizes is developed by a solvothermal-assisted liquid phase exfoliation process, consisting of ball milling-thinning, solvothermal swelling, and probe ultrasonic delamination. The exfoliation effect of the bulk B precursors is related to the surface tension and Hildebrand parameter of the selected solvents such as acetone, N,N-dimethyl formamide (DMF), acetonitrile, ethanol, and N-methyl pyrrolidone (NMP), and a relative small surface tension when using solvents is favorable for the exfoliation of bulk B. Four-layer thick borophene and an average lateral size of 5.05 μm can be obtained in acetone as the exfoliating solvent. The surface composition of the exfoliated few-layer borophene with large flake size hardly changes, while the chemical state of B changes to some extent because they are partly oxidized on the surface by contaminates before and after exfoliation. This acetone solvothermal-assisted liquid phase exfoliation technique can be used to prepare high quality borophene with large horizontal sizes, and it will provide the basis to study few-layer borophene with large sizes further.

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