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Three-dimensional (3D) reduced graphene oxide (rGO) anchored carbon-coated Fe 2 O 3 core-shell nanoparticles (Fe 2 O 3 @C-rGO) has been developed successfully through a simple one-pot hydrothermal process followed by a further annealing treatment. The 3D Fe 2 O 3 @C-rGO nanocomposite consists of carbon-coated Fe 2 O 3 nanoparticle clusters (Fe 2 O 3 @C) and rGO nanosheets. The homogenously distributed and intercalated Fe 2 O 3 @C nanoparticles between rGO nanosheets form a highly conductive 3D carbon network with rGO, and present a hierarchical pore size structure, enabling fast ion and electron transport, as well as remarkable specific surface area. The electrochemical performance in supercapacitor has been characterized, and the as-prepared Fe 2 O 3 @C-rGO electrode shows a significant high specific capacitance of 211.4 F/g at 0.5 A/g and 177.2 F/g at 20 A/g with no visible performance decay even after 2500 cycles testing. These properties indicate a good potential to achieve high performance electrochemical devices. [ABSTRACT FROM AUTHOR]

A free-standing Fe 3 O 4 /rebar graphene (FRG) composite film was obtained through solvothermal method. The microstructure, phases, electrochemical performance of the composite used as anode in lithium ion battery have been characterized by SEM, TEM, XRD, Raman, FT-IR and electrochemical measurements. In rebar graphene (RG), the single-wall carbon nanotubes (SWCNTs) and graphene are interconnected via π–π stacking and covalent bonding. SWCNTs can keep the graphene in RG from fracture and maintain the integrity of the composite electrodes during lithiation/delithiation. The absence of additive and conductive agent can enhance electrochemical performance of FRG composite by losing redundant weight. The FRG composite exhibits an outstanding rate capability with an excellent cycling performance (1038 mAh g −1 after 100 cycles at 100 mA g −1 ). [ABSTRACT FROM AUTHOR]

The segregation of alien solute atoms at grain boundaries (GBs) in nanocrystalline materials can dramatically affect their macroscopic properties. As important solutes in Al alloys, Mg and Cu atoms have been experimentally observed to segregate at GBs, which would render a significant impact on the material. In this work, first-principles calculations were used to conduct a systematic and comprehensive investigation to reveal the segregation behavior of Mg and Cu atoms at Al Σ5 (310) and Σ9 (221) GBs and its effect on GB properties. The negative segregation energy demonstrates that both Mg and Cu have a strong tendency to segregate to the Al GBs. Moreover, the segregation of Mg and Cu atoms can reduce the GB energy, indicating an increased thermodynamic stability of the GBs. Mechanical properties are explored by a combination of canonical Griffith fracture model with ab-initio tensile test method. Results reveal that the doped Mg will embrittle both GBs due to the elongation of interatomic bonds and depletion of charge density across the GBs. Contrarily, the segregated Cu contributes greatly to enhancing the GB strength by creating strong Cu-Al bonds with surrounding Al at GBs. Besides, the increased tensile separation displacement of GBs with Cu segregation also suggests an improved resistance to fracture, especially the Σ9 (221) GB. This work provides a theoretical understanding for the changes in microscopic properties of Al GBs caused by Mg and Cu segregation from an atomic and electronic level. [Display omitted] • Mg/Cu solutes have strong segregation tendency toward Ʃ5 (310) and Ʃ9 (221) GBs in Al alloys. • Mg/Cu segregation thermodynamically stabilizes the Ʃ5 (310) and Ʃ9 (221) GBs. • Mg doping causes embrittlement of Al GBs while Cu segregation will enhance the GB cohesion. [ABSTRACT FROM AUTHOR]