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In this article, a simple self-assembly strategy for fabricating van der Waals heterostructures from isolated two-dimensional atomic crystals is presented. Specifically, dopamine (DOPA), an excellent self-assembly agent and carbon precursor, was adsorbed on exfoliated MoS2monolayers through electrostatic interaction, and the surface-modified monolayers self-assembled spontaneously into DOPA-intercalated MoS2. The subsequent in situ conversion of DOPA to highly conductive nitrogen-doped graphene (NDG) in the interlayer space of MoS2led to the formation of a novel NDG/MoS2nanocomposite with well-defined alternating structure. The NDG/MoS2was then studied as an anode for lithium-ion batteries (LIBs). The results show that alternating arrangement of NDG and MoS2triggers synergistic effect between the two components. The kinetics and cycle life of the anode are greatly improved due to the enhanced electron and Li+transport as well as the effective immobilization of soluble polysulfide by NDG. A reversible capacity of more than 460 mAh/g could be delivered even at 5 A/g. Moreover, the abundant voids created at the MoS2–NDG interface also accommodate the volume change during cycling and provide additional active sites for Li+storage. These endow the NDG/MoS2heterostructure with low charge-transfer resistance, high sulfur reservation, and structural robustness, rendering it an advanced anode material for LIBs.

In this work, solid, hollow, and porous carbon nanofibers (SNFs, HNFs, and PNFs) were used as hosts to grow MoS2nanosheets hydrothermally. The results show that the nanosheets on the surface of SNFs and HNFs are comprised of a few grains stacked together, giving direct carbon–MoS2contact for the first grain and indirect contact for the rest. In contrast, the nanosheets inside of PNFs are of single-grain size and are distributed evenly in the mesopores of PNFs, providing efficient MoS2–carbon contact. Furthermore, the nanosheets grown on the polydopamine-derived carbon surface of HNFs and PNFs have larger interlayer spacing than those grown on polyacrylonitrile-derived carbon surface. As a result, the MoS2nanosheets in PNFs possess the lowest charge-transfer resistance, the most accessible active sites for lithiation/delithiation, and can effectively buffer the volume variation of MoS2, leading to its best electrochemical performance as a lithium-ion battery anode among the three. The normalized reversible capacity of the MoS2nanosheets in PNFs is about 1210 mAh g–1at 100 mA g–1, showing the effective utilization of the electrochemical activity of MoS2.

In this work, highly flexible MoS2-based lithium-ion battery anodes composed of disordered thin MoS2nanoflakes encapsulated in amorphous carbon nanofibrous mats were fabricated for the first time through hydrothermal synthesis of graphene-like MoS2, followed by electrospinning and carbonization. X-ray diffraction as well as scanning and transmission electron microscopic studies show that the as-synthesized MoS2nanoflakes have a thickness of about 5 nm with an expanded interlayer spacing, and their structure and morphology are well-retained after the electrospinning and carbonization. At relatively low MoS2contents, the nanoflakes are dispersed and well-embedded in the carbon nanofibers. Consequently, excellent electrochemical performance, including good cyclability and high rate capacity, was achieved with the hybrid nanofibrous mat at the MoS2content of 47%, which may be attributed to the fine thickness and multilayered structure of the MoS2sheets with an expanded interlayer spacing, the good charge conduction provided by the high-aspect-ratio carbon nanofibers, and the robustness of the nanofibrous mat.

1D hierarchical tubular MnO2nanostructures have been prepared through a facile hydrothermal method using carbon nanofibres (CNFs) as sacrificial template. The morphology of MnO2nanostructures can be adjusted by changing the reaction time or annealing process. Polycrystalline MnO2nanotubes are formed with a short reaction time (e.g., 10 min) while hierarchical tubular MnO2nanostructures composed of assembled nanosheets are obtained at longer reaction times (>45 min). The polycrystalline MnO2nanotubes can be further converted to porous nanobelts and sponge-like nanowires by annealing in air. Among all the types of MnO2nanostructures prepared, tubular MnO2nanostructures composed of assembled nanosheets show optimized charge storage performance when tested as supercapacitor electrodes, for example, delivering an power density of 13.33 kW·kg–1and a energy density of 21.1 Wh·kg–1with a long cycling life over 3000 cycles, which is mainly related to their features of large specific surface area and optimized charge transfer pathway.