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Graphical abstract Highlights • Mesoporous NiO/GNS composites were fabricated by in-situ thermal deposition. • Graphene matrix serves as an efficient conductive network for supercapacitor electrodes. • Graphene matrix offered accessible electroactive sites for electrochemical reactions. • The nanocomposites exhibited high performance as supercapacitor electrodes. Abstract Scholars have attached increasing attention to Graphene nanosheet (hereinafter referred to as GNS)-loaded transition metal oxide composites owing to the ability of attaching inorganic nanoparticles with better capacity and capacitance and better capacity than GNS of conductive polymer materials. A novel mesoporous structure of NiO nanoplates encapsulated in graphene matrix was synthesized and designed rationally. The composite composed of GNS and mesoporous NiO nanoplates can expand the approximate specific surface area of electrolyte. It has various advantages, such as good charge transport and short ion diffusion path. In addition, the interconnected graphene conducting network, as an adhesive, can maintain structural stability and promote charge transport by encapsulating mesoporous NiO nanoplates. The specific capacity is increased to 1050 F g−1 through the improved optimized NiO/GNS hybrid electrodes. This study provides a new idea for the design and manufacture of high performance transition metal oxide energy storage devices. [ABSTRACT FROM AUTHOR]

Graphical abstract Using graphene as a conductive matrix, the homogeneous distribution of Co 3 O 4 nanoparticles was accomplished and volume changes in the nanoplates during charge–discharge process were effectively accommodated, resulting in the excellent electrochemical performance of the composites. The mesoporous structure of the Co 3 O 4 nanoparticles was suitable for the transfer of Ionic electrolyte by the electrochemical reaction. Co 3 O 4 /graphene nanocomposites are a candidate material for high-capacity, low-cost, and nontoxic electrode for supercapacitors. Highlights • Co 3 O 4 /graphene composites were prepared via an in situ thermal deposition method. • Graphene serves as an efficient conductive network for electrochemical reactions. • The nanocomposites exhibited high performance as supercapacitor electrodes. Abstract In situ synthesis of mesoporous Co 3 O 4 nanoparticles embedded in reduced graphene oxide nanosheets (GNSs) was implemented through coprecipitation method and pyrolytic process. In the charge-discharge process, electrolyte ions can fill with three-dimensional GNS matrix with connected pore network structures and mesoporous Co 3 O 4 nanoparticles with uniform nanoscale structures as double ion buffer reservoirs. The capacitance value of Co 3 O 4 /GNS nanocomposites is 1085.6 F g−1 at the current density of 2 A g−1 in 2 M KOH solution. The composite has good cyclic stability, and the maximum capacitance loss is only 17.3% in 10,000 successive cycles. [ABSTRACT FROM AUTHOR]

Mesoporous silicon microspheres were fabricated via in situ magnesiothermic reduction of silicon oxide. Scanning and transmission electron microscopy images indicate that the diameter of the mesoporous silicon microspheres is approximately 500 nm. Mesopores with diameters ranging from 10 to 30 nm are homogeneously distributed in the silicon microspheres. The as-prepared mesoporous silicon microspheres show a reversible capacity of 3000 mAh g at 100 mA g discharge current density. After 60 cycles, the mesoporous silicon microspheres can still deliver a 1500 mAh g capacity at 1000 mA g discharge current density. The high reversible capacity, excellent cycling, and good rate capability of the fabricated material can be attributed to its mesoporous morphology and ultrafine particle size. [ABSTRACT FROM AUTHOR]

Abstract: Co3O4/graphene nanosheet (GNS) composites were synthesized via the in situ growth of mesoporous Co3O4 nanoparticles on graphene. The as-prepared Co3O4/GNS composites exhibited superior Li-ion battery performance and showed a large reversible capacity, excellent cycling, and good rate capability when used as an anode material in lithium ion batteries (LIBs). The uniform coating of Co3O4 around the graphene surface ensured tight electrical contact, resulting in a material with higher specific capacity and enhanced cycling performance compared with pure Co3O4 electrodes. The composites delivered a reversible capacity of 900mAhg−1 at a discharge current density of 100mAg−1 with good cycling ability. Moreover, the composites showed exceptional high-current charge–discharge performance, achieving 650mAhg−1 at a current density of 1000mAg−1. [Copyright &y& Elsevier]

In response to an increasing demand for understanding electrochemical processes on the nanometer scale, it now becomes possible to monitor electron transfer reactions at the single-nanoparticle level, namely particle collision electrochemistry. This technique has great potential in the development of research tools towards single-particle electrocatalysis and selective and multiplexed particle sizing. However, one existing problem that may discourage these applications is the relatively weak colloidal stability of nanoparticles in an electrolytic solution. Here we report on a facile but efficient way to achieve a good stability of gold nanoparticles in an acidic media so that ‘zero-aggregation’ collisions can be achieved at a carbon ultramicroelectrode. This allows us to obtain anodic dissolution currents from individual nanoparticles in a ‘one particle at a time’ manner, based on which accurate particle sizing with a resolution of 1–2 nm can be achieved. Our work strongly suggests that to maintain a well dispersed nanoparticle solution during a particle impact electrochemical experiment is critically important for accurate particle sizing, as well as other applications that require information to be extracted from individual nanoparticles (not their aggregates). [ABSTRACT FROM AUTHOR]

Abstract: CuO nanoparticles are directly formed on graphene nanosheets through the in situ chemical decomposition of Cu(NO3)2·3H2O and are anchored tightly on the graphene surface. The lithiation-induced strain is naturally accommodated, owing to the constraint effect of the graphene matrix. Electrochemical characterization shows that CuO nanoparticles anchored on graphene sample exhibits a high capacity of about 660mAh/g at a discharge current density of 100mA/g and a good cycling ability. During the charge–discharge process, graphene nanosheets not only served as a three-dimensional conductive network for CuO nanoparticles, but also improve the detachment and agglomeration of CuO nanoparticles. This CuO/graphene nanocomposite displays superior Li-battery performance with large reversible capacity, excellent cyclic performance, and good rate capability. [Copyright &y& Elsevier]

Abstract: A MnO nanoparticle/graphene composite was prepared via in situ carbothermal reduction of Mn3O4 on the surface of graphene nanosheets. The formed MnO nanoparticles with diameters ranging from 20nm to 250nm integrated tightly with the graphene nanosheets. As anode material for lithium-ion batteries, the nanocomposite showed a high specific capacity of approximately 700mAhg−1 at 100mAg−1, excellent cyclic stability, and good rate capability. During the charge-discharge process, graphene nanosheets served as a three-dimensional conductive network for MnO nanoparticles. Furthermore, the detachment and agglomeration of MnO nanoparticles were effectively prevented due to the tight combination of MnO nanoparticles and graphene. [Copyright &y& Elsevier]

Graphene is an excellent substrate to load nanomaterials for energy applications due to its large surface area, excellent conductivity, mechanical strength, and chemical stability. In this study, thermal exfoliated functionalized graphene sheets with good conductivity and high BET surface area are anchored with mesoporous NiO nanoplates by in situ chemical synthesis approach. Electrochemical characterization shows that functionalized graphene sheets-NiO sample exhibits a high capacity of about 700 mAh/g at a discharge current density of 100 mA/g and a good cycling ability. The high capacity and good cycling ability of functionalized graphene sheets -NiO material were attributed to the intimate interaction between the graphene sheets and NiO nanoplates. The graphene sheets not only enhance the conductivity of NiO nanoplates but also improve the structure stability of NiO nanoplates. Furthermore, the mesoporous structure of NiO nanoplates is available to the transfer of electrolyte. Such functionalized graphene sheets-NiO nanocomposite could be a promising candidate material for a high-capacity, low cost, and nontoxic anode for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Graphene-SnS nanocomposites were prepared via a solvothermal method with different loading of SnS. The nanostructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD patterns revealed that hexagonal SnS was obtained. SEM and TEM results indicated that SnS particles distributed homogeneously on graphene sheets. The electrochemical properties of the samples as active anode materials for lithium-ion batteries were examined by constant current charge-discharge cycling. The composite with weight ratio between graphene and SnS of 1:4 had the highest rate capability among all the samples and its reversible capacity after 50 cycles was 351 mAh/g, which was much higher than that of the pure SnS (23 mAh/g). With graphene as conductive matrix, homogeneous distribution of SnS nanoparticles can be ensured and volume changes of the nanoparticles during the charge and discharge processes can be accomodated effectively, which results in good electrochemical performance of the composites. [ABSTRACT FROM AUTHOR]