The synthesis of vertical ReS2 nanowalls on 3D graphene foam (V-ReS2 /3DGF) is demonstrated by a chemical vapor deposition route. The vertical nanowall structure leads to an effective exposure of active sites and enhances the lithium interaction with all of the layers. When serving as the anode material for lithium-ion batteries, the V-ReS2 /3DGF composite demonstrates excellent cycling stability at high-current-density.

The development of two‐dimensional (2D) materials is experiencing a renaissance since the adventure of graphene. 2D materials typically exhibit strong in‐plane covalent bonding and weak out‐of‐plane van der Waals interactions through the interlayer gap. Opening 2D materials is an effective way to alter the physical and chemical properties, such as band gap, conductivity, optical property, thermoelectric property, photovoltaic property and superconductivity. A larger interlayer distance means more accessible active sites for catalysis, an ion‐accessible surface in the interlayer space, which may greatly enhance the performance of 2D materials for energy conversion and storage. Moreover, opening 2D materials by intercalation can change the band filling state and the Fermi level. This review mainly focuses on the opening of 2D materials and their subsequent applications in energy conversion and storage fields, expecting to promote the development of such a new class of materials, namely expanded 2D materials. The exciting progresses of these expanded materials made in both energy conversion and storage devices including solar cells, thermoelectric devices, electrocatalyst, supercapacitors and rechargeable batteries, is presented and discussed in depth. Furthermore, prospects and further developments in these exciting fields of the expanded 2D materials are also commented.

Magnetite (Fe3O4) is an attractive electrode material due to its high theoretical capacity, eco-friendliness, and natural abundance. However, its commercial application in lithium-ion batteries is still hindered by its poor cycling stability and low rate capacity resulting from large volume expansion and low conductivity. We present a new approach which makes use of supercritical carbon dioxide to efficiently anchor Fe3O4 nanoparticles (NPs) on graphene foam (GF), which was obtained by chemical vapor deposition in a single step. Without the use of any surfactants, we obtain moderately spaced Fe3O4 NPs arrays on the surface of GF. The particle size of the Fe3O4 NPs exhibits a narrow distribution (11 ± 4 nm in diameter). As a result, the composites deliver a high capacity of about 1200 mAh g(-1) up to 500 cycles at 1 C (924 mAh g(-1)) and about 300 mAh g(-1) at 20 C, which reaches a record high using Fe3O4 as anode material for lithium-ion batteries.

Newborntwo-dimensional materials (NB2DMs) beyond graphene such as transition metal dichalcogenides (TMDs) exhibit excellent optoelectronic and mechanical properties as well as high theoretical specific capacity, which make them become the promising building blocks of flexible energy devices related to energy conversion and storage. Compared to graphene with zero band gap or traditional friable materials such as Si, these NB2DMs are more suitable to construct flexible devices as active layers of optoelectronic devices or as active materials for batteries. The present review focuses on the recent advances in bendable energy devices based on NB2DMs, including batteries, supercapacitors (SCs), solar cells, photodetectors and nanogenerators (NGs). The NB2DMs pave a new way to construct next-generation flexible energy devices with improved performance and we believe that those devices will be seen in our daily life and change our lifestyle in the immediate future.

The self-assembly of two-dimensional (2D) nanomaterials, an emerging research area, still remains largely unexplored. The strong interlayer attraction between 2D nanosheets leads to face-to-face stacking rather than edge-to-edge coupling. We demonstrate, for the first time, how one can induce and control an edge-to-edge self-assembly process for 2D nanomaterials. The extremely weak van der Waals coupling and strong anisotropy of ReS2 allow us to realize an oriented self-assembly (OSA) process. The aspect ratio of the resulting ReS2 nanoscrolls can be well controlled. In addition, we perform simulations to further explain and confirm the OSA process, demonstrating its great potential to be expanded as a general edge-to-edge self-assembly process suitable for other 2D nanomaterials.