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Graphene quantum dots (GQDs) have attracted tremendous research interest due to the unique properties associated with both graphene and quantum dots. Here, a new application of GQDs as ideal electrode materials for supercapacitors is reported. To this end, a GQDs//GQDs symmetric micro-supercapacitor is prepared using a simple electro-deposition approach, and its electrochemical properties in aqueous electrolyte and ionic liquid electrolyte are systematically investigated. The results show that the as-made GQDs micro-supercapacitor has superior rate capability up to 1000 V s−1, excellent power response with very short relaxation time constant ( τ0 = 103.6 μs in aqueous electrolyte and τ0 = 53.8 μs in ionic liquid electrolyte), and excellent cycle stability. Additionally, another GQDs//MnO2 asymmetric supercapacitor is also built using MnO2 nanoneedles as the positive electrode and GQDs as the negative electrode in aqueous electrolyte. Its specific capacitance and energy density are both two times higher than those of GQDs//GQDs symmetric micro-supercapacitor in the same electrolyte. The results presented here may pave the way for a new promising application of GQDs in micropower suppliers and microenergy storage devices. [ABSTRACT FROM AUTHOR]

In this study, the electrochemical properties of graphene nanosheet (GNS) electrodes are evaluated in depth by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques in [Et4N]BF4/acetonitrile electrolyte, [BPy]BF4/acetonitrile electrolyte, [BMIM]BF4/acetonitrile electrolyte and [P4,4,4,4]BF4/acetonitrile electrolyte, respectively. The electrochemical results exhibit that GNSs show good supercapacitive properties in these aforementioned four non-aqueous electrolytes, especially in [Et4N]BF4/acetonitrile electrolyte. It is also observed that the rate performance and the specific capacitance of GNS electrode increase in the order of [P4,4,4,4]BF4/acetonitrile ＜ [BMIM]BF4/acetonitrile ≈ [BPy]BF4/acetonitrile ＜ [Et4N]BF4/acetonitrile in these four non-aqueous electrolytes. The reasons are attributed to the difference of the relative ionic size and the discrepancy in the functional group among these four non-aqueous electrolytes, which result in the differences of equivalent series resistance, charge transfer resistance, and rate performance. In addition, the GNS electrode shows excellent stability in these four non-aqueous electrolytes after 1500 repeating charge–discharge cycles. These results may provide valuable information to explore new electrolytes and illustrate the exciting potential for high performance supercapacitors based on GNSs. [ABSTRACT FROM AUTHOR]

The friction and wear behavior of silicone oil 114(114SO), a linear perfluoroalkyl polyether Z-25, polyalphaolefin (PAO) and multiply alkylated cyclopentane (MAC) for five friction couples are evaluated using a SRV tester at room temperature and the tribological performances of MAC are compared with those of the other three liquid lubricants. The test results indicated that MAC exhibits better excellent friction reduction and anti-wear properties than the three other liquid lubricants when they are used to lubricate the friction couple materials of GCr15 steel vs. GCr15 steel, Si3N4 vs. Si3N4, and GCr15 steel vs. Si3N4 respectively. When being used to lubricate the friction couple materials of GCr15 steel vs. copper-tin alloy and GCr15 steel vs. 1Cr18Ni9Ti stainless steel at lower loads, MAC also has good friction reduction and anti-wear properties. [ABSTRACT FROM AUTHOR]

To enhance the interfacial interaction in silica-nanoparticle-filled polymer composites, an effective surface modification method was developed by grafting polystyrene onto the nanoparticles. That is, the silica surface was first treated with silane to introduce the methacryloxypropyl, followed by radical copolymerization with styrene via a dispersion polymerization method. Results of elemental analysis (EA), IR, XPS and TEM demonstrated that the desired polymer chains were covalently bonded to the surface of the silica nanoparticles. A percentage of grafting (PG) of 49.5% was achieved when 2.44 mmol AIBN was used as initiator. The resulting products could be used as nanocomposites directly, or the PS-grafted silica nanoparticles (PS-SNs) could be separated and used as nanofillers for polymers. [ABSTRACT FROM AUTHOR]

A new application of graphene quantum dots (GQDs) as an ideal electrode material for supercapacitors is explored by X.‐B. Yan and co‐workers. On page 4111 they build a GQD//GQD symmetric micro‐supercapacitor and a GQD//MnO2 asymmetric supercapacitor. Both devices show excellent rate capabilities, exceptionally high‐frequency responses, and long‐term cycle stability. [ABSTRACT FROM AUTHOR]

Highlights: [•] Highly stable dispersion of monodisperse Ag nanoparticles (1–2nm) was obtained. [•] Poly-amino compounds were used as effective stabilizing agent in nonaqueous medium. [•] The robust one-step route is simple and highly reproducible. [ABSTRACT FROM AUTHOR]

Abstract: Highly stable dispersion of silver nanoparticles (Ag NPs) (1–2nm in diameter) having low size distribution was synthesized using a straightforward one-step synthesis method. Tetraethylenepentamine (TEPA), a kind of aliphatic amine, was utilized as stabilizing agent to prevent the aggregation of Ag NPs in nonaqueous medium. The successful formation of TEPA-stabilized Ag NPs was demonstrated by ultraviolet–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The mechanism of TEPA on the stabilization of Ag NPs is also discussed. This facile one-step synthesis route may provide a new perspective for creating other nanoparticles that have potential application in various nanotechnology fields. [Copyright &y& Elsevier]