Graphene has aroused intensive interest because of its unique structure, superior properties, and various promising applications. Graphene nanostructures with significant disorder and defects have been considered to be poor materials because disorder and defects lower their electrical conductivity. In this paper, we report that highly disordered graphene nanosheets can find promising applications in high-capacity Li ion batteries because of their exceptionally high reversible capacities (794−1054 mA h/g) and good cyclic stability. To understand the Li storage mechanism of graphene nanosheets, we have prepared graphene nanosheets with structural parameters tunable via different reduction methods including hydrazine reduction, low-temperature pyrolysis, and electron beam irradiation. The effects of these parameters on Li storage properties were investigated systematically. A key structural parameter, Raman intensity ratio of D bands to G bands, has been identified to evaluate the reversible capacity. The greatly enhanced capacity in disordered graphene nanosheets is suggested to be mainly ascribed to additional reversible storage sites such as edges and other defects.

SnS2 materials have attracted broad attention in the field of electrochemical energy storage due to their layered structure with high specific capacity. However, the easy restacking property during charge/discharge cycling leads to electrode structure instability and a severe capacity decrease. In this paper, we report a simple one-step hydrothermal synthesis of SnS2/graphene/SnS2 (SnS2/rGO/SnS2) composite with ultrathin SnS2 nanosheets covalently decorated on both sides of reduced graphene oxide sheets via C–S bonds. Owing to the graphene sandwiched between two SnS2 sheets, the composite presents an enlarged interlayer spacing of ∼8.03 Å for SnS2, which could facilitate the insertion/extraction of Li+/Na+ ions with rapid transport kinetics as well as inhibit the restacking of SnS2 nanosheets during the charge/discharge cycling. The density functional theory calculation reveals the most stable state of the moderate interlayer spacing for the sandwich-like composite. The diffusion coefficients of Li/Na ions from both molecular simulation and experimental observation also demonstrate that this state is the most suitable for fast ion transport. In addition, numerous ultratiny SnS2 nanoparticles anchored on the graphene sheets can generate dominant pseudocapacitive contribution to the composite especially at large current density, guaranteeing its excellent high-rate performance with 844 and 765 mAh g–1 for Li/Na-ion batteries even at 10 A g–1. No distinct morphology changes occur after 200 cycles, and the SnS2 nanoparticles still recover to a pristine phase without distinct agglomeration, demonstrating that this composite with high-rate capabilities and excellent cycle stability are promising candidates for lithium/sodium storage.

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R-Fe 2 O 3 nanoparticulate films could be formed on the surface of R-Fe 2 O 3 hydrosol after aging of the hydrosol or by compressing of the nanoparticles on the sol surface, in which a three-dimensional ordered structure was constructed by the Langmuir-Blodgett technique and colloid chemical methods. The structure of the LB film was characterized by AFM, TEM, XPS, and UV-vis spectra and small-angle X-ray diffraction. Gas-sensing measurement shows that the LB film has good sensitivity to alcohols at room temperature.

As one type of advanced alternative batteries, zinc-ion batteries (ZIBs) have attracted increasing attention because of their advantages of cost-effectiveness, high safety and environmentally benign features. However, the performance of cathode materials has become a bottleneck for the future application of ZIBs. In recent years, manganese dioxide (MnO2)-based materials as cathodes for ZIBs have been intensively explored. In this review, recent advances in MnO2-based cathode materials for ZIBs are comprehensively reviewed with a discussion about the reaction mechanisms for the fundamental understanding of the electrochemical processes. Furthermore, several challenges hindering the technology maturity are also analyzed with corresponding strategies to further improve the electrochemical performance of such Zn–MnO2 batteries.

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Tin oxide is a unique material of widespread technological applications, particularly in the field of environmental functional materials. New strategies of fractal assessment for tin dioxide thin films formed at different substrate temperatures are of fundamental importance in the development of microdevices, such as gas sensors for the detection of environmental pollutants. Here, tin dioxide thin films with interesting fractal features were successfully prepared by pulsed laser deposition techniques under different substrate temperatures. Fractal method has been first applied to the evaluation of this material. The measurements of carbon monoxide gas sensitivity confirmed that the gas sensing behavior is sensitively dependent on fractal dimensions, fractal densities, and average sizes of the fractal clusters. The random tunneling junction network mechanism was proposed to provide a rational explanation for this gas sensing behavior. The formation process of tin dioxide nanocrystals and fractal clusters could be reasonably described by a novel model.