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Copper matrix composites reinforced with graphene nanoplatelets (GNPs) were prepared by vacuum hot pressing of ball milled mixtures of powders. Two grades of GNPs were used; one with average thickness of 2 nm and average lateral size of 6  μ m and another with much larger lateral size of 80  μ m. Microstructure and properties of as-prepared composites containing 10 vol.% GNPs were studied. The GNPs sheets are uniformly distributed and well aligned in the Cu matrix. The microstructure observation shows that the GNPs-2–6 exhibits a better dispersion in the Cu matrix than GNPs-2–80. The addition of fine GNPs-2–6 lead to ∼ 31% higher tensile strength and approximately same electrical conductivity of the Cu matrix, while the GNPs-2–80/Cu composite only shows a ∼ 15% increase of tensile strength and a lower electrical conductivity than the Cu matrix. [ABSTRACT FROM AUTHOR]

In this work, we report a strategy for enhancing the pseudocapacitive performance of MoS 2 materials by the introduction of nitrogen-doped graphene quantum dots (N-GQDs) and helical carbon tubes (HCNT). By a simple hydrothermal process, the hybrid composite (MoS 2 , N-GQDs and HCNT) were coated on the carbon cloth (CC) without any binders, which can be directly used as advanced electrode material for high-performance solid-state flexible supercapacitors. In this hybrid structure, N-GQDs are inserted between the layers of MoS 2 nanosheets, which induce and expose more active sites for pseudocapacitance contributions in MoS 2 electrode materials. Meanwhile, HCNT acts as electrically conducting bridge for enhancing the electrical conductivity of MoS 2 nanosheets and speeding up transport of electronic. As results, the hybrid composite (MoS 2 , N-GQDs and HCNT) show higher capacitive performance than pure MoS 2. The specific capacitance of hybrid composite is high up to 3360 mF cm−2. Further, the assembled solid-state flexible supercapacitor shows high specific capacitance of 1893 mF cm−2, outstanding cycle life (capacitance retention of 86% after 2500 cycles), good mechanical stability and great flexibility. Our work provides a reference for the preparation of MoS 2 composites with high supercapacitive performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]