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Graphene-based nanocomposites have been widely investigated as promising anode materials because of the high specific capacity and good rate capability. However, effective distributing the nanomaterials into graphene conductive network still remains some challenges. In this study, the supercritical carbon dioxide (SC-CO 2 ) route as a good strategy is developed to prepare SnS 2 /reduced graphene oxide (RGO) nanocomposites, which integrates the complementary effect of ultrasmall SnS 2 nanopaticle and RGO nanosheet in the nanocompositions. The SnS 2 /RGO nanocomposite exhibits high initial discharge capacity of 1466.1 mA h g −1 (100 mA g −1 ), good capacity retention of about 492 mA h g −1 (100 mA g −1 ) after 70 cycles and good rate capacity as an anode material for lithium ion batteries. These results demonstrate that supercritical CO 2 (SC-CO 2 ) possess significant technological value to enhance the energy storage properties of other two-dimensional (2D) nanocomposites. [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: 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]

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]

To better understand the occurrence state and characteristics of naturally formed TiO 2 in the environment, four types of different natural media were collected from nine areas distributed throughout five different provinces in China. For the first time, this study demonstrated that naturally formed TiO 2 nanoparticles are widely distributed in various media (soil solid, underground water, geogas and organisms) on the surface of the earth. With the help of a high-resolution transmission electron microscope (TEM), the morphology, chemical composition and crystal structure of TiO 2 nanoparticles in natural media were obtained. The characteristics of natural TiO 2 nanoparticles were found to be different from those of engineered TiO 2 nanoparticles, while natural TiO 2 nanoparticles in different media were found to have similar characteristics. In general, single naturally formed TiO 2 nanoparticles usually appear as complete or incomplete polygons, while aggregations of naturally formed TiO 2 nanoparticle are mostly irregular in shapes. The main growth stages of TiO 2 crystals in natural media were also investigated in this study. In brief, along with the crystal shapes of the TiO 2 particles changing from imperfect to perfect, the degree of crystallinity of the particles was also gradually improved. Furthermore, natural TiO 2 nanoparticles were found to always carry some amount of other elements related to the surrounding environment, resulting in a more complex composition. This phenomenon may contribute to the interpretation of elemental migration and ore prospecting to some degree, but the potential environmental hazards associated with TiO 2 nanoparticles may be enhanced as well. Unlabelled Image [ABSTRACT FROM AUTHOR]

• Nanoparticles in groundwater were investigated using TEM. • Nanoparticles with different contents of ore-forming elements can be grouped into three main types. • A relationship between metal-bearing nanoparticles and concealed orebodies was demonstrated. • Classification of ore-related nanoparticles was important for the detection of mineralization information. The characterization of nanoparticles in groundwater is recognized as an important tool that can be applied to mineral exploration. In this paper, we investigate the concealed orebodies of the Qujia gold deposit in the Jiaojia orefield of eastern China by analyzing ore-related nanoparticles in groundwater using transmission electron microscopy. The nanoparticles contain variable amounts of ore-related elements (e.g., Ag, Cu, Zn, La, Ce, Pb, Pt, and S). Some of these elements are rarely found in natural settings unrelated to orebodies or mineral extraction, but are strongly linked to concealed orebodies in the study area. These nanoparticles, which are diverse in their shapes, aggregated features, and degrees of crystallinity, can be grouped in terms of composition as: (i) native metal nanoparticles, (ii) metal-based nanoparticles, and (iii) carrier nanoparticles associated with trace elements. We propose that these three main types of nanoparticles enable the efficient transport of ore-forming elements in groundwater. The results of this study provide insights into the migratory behaviour of ore-related nanoparticles in groundwater, and our methods could be applied for detecting deep-seated mineral deposits. [ABSTRACT FROM AUTHOR]