No abstract

As a typical two‐dimensional (2D) layered material, (vanadium disulfide) VS2 has huge potentials for application in SIBs due to its large interlayer spacing and high conductivity compared to metal oxide or other 2D materials. Reduced graphene oxide (RGO) possesses exceptional electronic properties and large specific area favoring fast electron transport and rich redox sites. In this work, VS2 hollow flower spheres and RGO nanocomposites were developed for the first time, it was synthesized using a facile solvothermal method. Benefiting from the exceptional layered structure, when used as the anode material for SIBs at room temperature, the as‐prepared electrode material of VS2 hollow flower spheres @RGO (named as VS2 HFS/RGO) nanocomposites delivers a high reversible discharge specific capacity of around 430 mAh/g at current density of 100 mA/g, superior rate performance (2 A/g) and excellent cycling properties with the discharge capacity remained 350 mAh/g at 100 mA/g after 500 cycles. Results show that the kinetics of VS2 HFS/RGO nanocomposites were mainly a capacitive‐controlled storage process and the high capacity contribution were beneficial for good rate performance. This work could provide new approaches and potentials for exploring and searching high performances anode materials for the practical applications of SIBs.

Recent advances in 2D transition metal dichalcogenides (TMDs) have led to a variety of promising technologies for nanoelectronics, photonics, sensing, energy storage, and optoelectronics. Among these dichalcogenides, tin sulfide (SnS2) has received great attention due to its high optical absorption coefficient, high theoretical capacitance, high natural abundance of precursor chemicals, and minimal impact of these on the environment (green chemistry). It is crucial to obtain materials with varied morphologies because the chemical and physical properties are dependent on the morphology. The controlled synthesis of SnS2 with a specific morphology, a hollow sphere, is of significant interest. Herein, a facile, template‐free, one‐step solvothermal method to prepare SnS2 spheres with a hollow structure is demonstrated. The size of the SnS2 hollow spheres is uniform, at 2 μm in diameter, and the walls of the sphere are only 300 nm thick. The hollow structure forms due to the different specific surface energies of the SnS2 sheets and the fluorine‐doped tin oxide (FTO) substrate. Furthermore, the possible growth mechanism of these SnS2 hollow spheres is proposed, which may be applied to other 2D TMD systems.

Tin sulphide (SnS2) shows great potential in photo‐/electrochemical applications including hydrogen evolution due to its unique layered structure, intrinsic semiconducting nature and high optical absorption capacity. Hollow structured SnS2 was synthesized by Xuexia He, Peng Hu and co‐workers (article no. http://doi.wiley.com/10.1002/pssr.201900185) on FTO glass by template‐free solvothermal routine. The studies of morphology evolution and phase changing indicate that SnS2 experienced the steps of tilted sheets aggregation, extensional growth with cross‐linking, formation of sphere wall starters, and then hollow structure completion. Specific surface energies difference between SnS2 material and FTO substrate is believed to be the origin to trigger the conformation of the special hollow structure. – The cover article belongs to the Focus Section “TMD Synthesis”, a compilation of 7 articles in this issue, guest‐edited by Zheng Liu (cf. Preface, article no. http://doi.wiley.com/10.1002/pssr.201900634).

Sodium-ion batteries (SIBs) have attracted increasing interest as promising candidates for large-scale energy storage due to their low cost, natural abundance and similar chemical intercalation mechanism with lithium-ion batteries. However, achieving superior rate capability and long-life for SIBs remains a major challenge owing to the limitation of favorable anode materials selection. Herein, an elegant one-step solvothermal method was used to synthesize VS4 nanorods and VS4 nanorods/reduced graphene oxide (RGO) nanocomposites. The effects of ethylene carbonate/diethyl carbonate(EC/DEC), ethylene carbonate/dimethyl carbonate(EC/DMC), and tetraethylene glycol dimethyl ether (TEGDME) electrolytes on the electrochemical properties of VS4 nanorods were investigated. The VS4 nanorods electrodes exhibit high specific capacity in EC/DMC electrolytes. A theoretical calculation confirms the advance of EC/DMC electrolytes for VS4 nanorods. Significantly, the discharge capacity of VS4/RGO nanocomposites remains 100 mAh/g after 2000 cycles at a large current density of 2 A/g, indicating their excellent cycling stability. The nanocomposites can improve the electronic conductivity and reduce the Na+ diffusion energy barrier, thereby effectively improving the sodium storage performance of the hybrid material. This work offers great potential for exploring promising anode materials for electrochemical applications.