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Fibers of regenerated silk fibroin (RSF) are usually brittle and weak, and this prevents its wide application as a structural material. To improve the mechanical properties of RSF, composite fibers of RSF reinforced via functional graphene oxide (FGO) with high strength were prepared by a simple and versatile method known as wet spinning. The greatest force at which hybrid fibers were made to break was 697 ± 22 MPa, which is a 58.7% improvement over the breakage force of pure RSF silk fiber. In addition, the as-prepared FGO/RSF nanocomposite fibers also exhibit significant activity against both Gram-negative and Gram-positive bacteria. The FGO/RSF composite fibers with good biocompatibility, the significant antibacterial activity and enhanced mechanical properties may have potential applications in tissue engineering, biomedical and biotechnological area. [ABSTRACT FROM AUTHOR]

Abstract: Due to the aggregation or restacking of graphene and the weak interactions between pristine graphene and polymeric matrices, a method to chemically functionalize graphene nanosheets by silylation was developed in this study. The silanized graphene oxide sheets were reduced to produce well water-soluble graphene derivatives after graphene oxide sheets silanized with 3-Methacryloxypropyltrimethoxysilane (MPS). The MPS-graphene oxide (MPS-GO) and MPS-reduced graphene oxide (MPS-RGO) could be redispersed in polar solvents, which could facilitate their incorporation into poly(methyl methacrylate) (PMMA) through in situ copolymerization method. The mechanical properties of the nanocomposites were studied after fabrication of the graphene/PMMA film through hot press process. And the MPS-RGO/PMMA composites with 0.5wt.% of MPS-RGO incorporation lead to a ∼44% increases in tensile strength than that of the reduced graphene oxide (RGO)/PMMA composites. [Copyright &y& Elsevier]

Transition metal-doped graphene single-atom catalysts exhibit great application prospects for catalyzing hydrogen evolution applications. However, the precise timing and control of the activity of central atoms is a key problem to ensure the further development of catalysts. Revealing the correlation between the catalytic activity of the central atom and the coordination environment (atomic species, coordination number, and geometric configuration) is regarded as quite crucial for solving this key problem. Along these lines, in this work, Fe as the central atom and N, S, and P doped porous graphene (DPG) as the matrix material were used to systematically study the correlation between the coordination environment and the stability, catalytic activity of the catalyst. From the acquired results, it was demonstrated that: (1) The binding strength between the Fe atom and the N-atom DPG is the highest, and the anchoring strength of the Fe atom on two-element doping doped graphene is relatively low. Under the tetrad coordination condition, the catalyst doped with S and P atoms showed excellent performance in hydrogen evolution and water activation. A moderate correlation between the hydrogen evolution performance (ΔGH∗, E A , and ΔGOH∗) and d -band electronic properties (d -CU and d -SE) under single element doping (four and three coordination) was also detected. In addition, a certain correlation between the Fe atom outer-shell electron (3d 4s) and the hydrogen evolution performance was found. A weak correlation between the electronic properties of the double element doped graphene and the hydrogen evolution performance was also confirmed from our simulations. The results are of great significance for the regulation of the single-atom catalyst activity. [Display omitted] • The anchoring strength of the S or P doped PG to Fe atom is lower than N-doped. • The S/P doped PG with tetrad coordination showed excellent activity catalysts. • The catalytic activity showed moderate correlation with d band electronic properties. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/SiO2 (RGO/SiO2) serving as a novel spherical support for Ziegler-Natta (Z-N) catalyst is reported. The surface and interior of the support has a porous architecture formed by RGO/SiO2 sandwich structure. The sandwich structure is like a brick wall coated with a graphene layer of concreted as skeleton which could withstand external pressures and endow the structure with higher support stabilities. After loading the Z-N catalyst, the active components anchor on the surface and internal pores of the supports. When the ethylene molecules meet the active centers, the molecular chains grow from the surface and internal catalytic sites in a regular and well-organized way. And the process of the nascent molecular chains filled in the sandwich structure polymerization could ensure the graphene disperse uniformly in the polymer matrix. Compared with traditional methods, the porous spherical graphene support of this strategy has far more advantages and could maintain an intrinsic graphene performance in the nanocomposites. [ABSTRACT FROM AUTHOR]

Improving volumetric capacitance of supercapacitor is important and challenging for practical application. Here, porous graphene oxide (PGO) is prepared through an efficient method at room temperature after etched by Zn(CH 3 COO) 2 in several minutes. The obtained densely packed porous graphene film (PGF) was constructed by a template-assisted method. And the perforated PGF electrode material exhibits a high volumetric capacitance (C V ) of 318.8 F cm −3 in 6.0 M KOH electrolyte at the current density of 1 A g −1 . In addition, it exhibited excellent cycling stability, that is 88% retention of capacitance after 10000 charge/discharge cycles in the current density of 5 A g −1 . Furthermore, it demonstrates a capacitance of 219.0 F cm −3 (1 A g −1 ) and a cycling stability of 113% (10000 charge/discharge cycles at 5 A g −1 ) after assembled into symmetric supercapacitor. So the PGF is promising to be applied in the high performance energy storage devices with lighter quality and smaller volume. [ABSTRACT FROM AUTHOR]

• N, S co-doped graphene could effectively improve the structural stability of NCS. • NCS-G 3 electrode exhibits a specific capacitance of 1145 F g−1. • The asymmetric supercapacitor device demonstrates the high energy density of 33.8 Wh kg−1. • The asymmetric supercapacitor exhibits good cycling performance. With high electrochemical activity and good energy storage performance, bimetallic pseudocapacitive materials of Ni-Co sulfides have been extensively and deeply researched. However, the low electrical conductivity, irreversible reduction reaction and structural instability significantly limit the practical application of bimetallic NiCo 2 S 4. In this work, NiCo 2 S 4 @N, S co-doped graphene (NCS-G) composite material with high electrochemical performance is prepared by an efficient chemical precipitation assisted hydrothermal method. As the ideal skeleton and excellent conductive network, N, S co-doped graphene could effectively improve the structural stability of the as-prepared NCS-G, thus increasing the utilization and efficient electron transfer of NCS. Notably, the NiCo 2 S 4 could not only provide numerous reaction sites, but also avoid the re-stacking of graphene sheets. Owing to the above merits, the NCS-G 3 electrode exhibits a maximum specific capacitance of 1145 F g−1 (at 0.5 A g−1). The rate performance of the electrode retains 91.7% at the current density of 10 A g−1 compared with that of 0.5 A g−1. Furthermore, consisting of the graphene anode and the NCS-G 3 cathode, the asymmetric SC device demonstrates the outstanding energy density of 33.8 Wh kg−1 at the power density of 799.8 W kg−1 and good cycling performance of 74.5% after 5000 cycles at 2 A g−1. The synthesis strategy exploited in this work endows the electrode with marvelous rate performance, providing a new pathway to engineer the promising electrode material and manufacture high-performance energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

• The TGOP-Na is synthesized based on an efficient chemical route. • The TGOP-Na electrode delivers a high volumetric capacitance of 469 F cm−3. • The TGOP-Na based supercapacitor exhibits a high volumetric energy density of 24.2 Wh L−1. • The supercapacitor can operate stably over 10,000 cycles with below 12% capacitance fade. With the rapid development of mobile electronics and electric vehicles, supercapacitors need to store as much energy as possible in relatively limited space. For aqueous-electrolyte supercapacitor, it is particularly important to design the electrode materials with high particle density, appropriate pore size distribution and doping degrees. In this work, we report an efficient approach to simultaneous increase the particle density and doping level of graphene-based electrode material. Through the interaction of oxygen functionalized graphene with NaOH solution, the electrostatic adsorption of sodium ions and oxygen-containing functional groups increases the density of the material while the reaction of hydroxide ions with oxygen-containing functional groups can increase the concentration of oxygen-containing functional groups of graphene. The as-prepared graphene displays both high particle density and pseudocapacitance which contributed from oxygen-containing functional groups. The graphene-based electrode delivers high volumetric capacitance of 469 F cm−3 as well as high rate capability (77% capacitance retention at 30 A g−1). Also, the assembled supercapacitor shows the high volumetric energy density of 24.2 Wh L−1, which is higher than most of the carbon materials in aqueous electrolyte. Therefore, this work provides a method to prepare high density and functionalized graphene, which has potential application in energy storage devices. [ABSTRACT FROM AUTHOR]