Boron Doped Graphene Quantum Structure and MoS2 Nanohybrid as Anode Materials for Highly Reversible Lithium Storage.

Herein, the boron-doped graphene quantum structure (BGQS), which contains both the advantages of 0-D graphene quantum dot and 2-D reduced graphene oxide, has been fabricated by top-down hydrothermal method and then mixed with molybdenum sulfide (MoS2) to serve as an active electrode material for the enhanced electrochemical performance of lithium ion battery. Results show that 30 wt% of BGQS/MoS2 nanohybrid delivers the superior electrochemical performance in comparison with other BGQS/MoS2 and bare components. A highly reversible capacity of 3,055 mAh g-1 at a current density of 50 mA g-1 is achieved for the initial discharge and a high reversible capacity of 1,041 mAh g-1 is obtained at 100 mA g-1 after 50 cycles. The improved electrochemical performance in BGQS/MoS2 nanohybrid is attributed to the well exfoliated MoS2 structures and the presence of BGQS, which can provide the vitally nano-dimensional contact for the enhanced electrochemical performance. Results obtained in this study clearly demonstrate that BGQS/MoS2 is a promising material for lithium ion battery and can open a pathway to fabricate novel 2-D nanosheeted nanocomposites for highly reversible Li storage application.

Synthesis and Characterization of Poly(N-vinylcarbazole)/Graphene Nanocomposites.

The present work describes the dual role of graphene as an initiator and filler for polymerization of N-vinylcarbazole and formation of poly(N-vinylcarbazole)/graphene (PVK/Gr) nanocomposites. Fourier transformation infrared (FTIR) and X-ray diffraction (XRD) studies confirmed the formation of PVK as well its graphene nanocomposites. Scanning electron micrograph (SEM) and transmission electron microscopy (TEM) revealed the graphene platelets are dispersed in the matrix of spherical PVK. X-ray photoelectron spectroscopy (XPS) also revealed formation of PVK and presence of interaction between PVK and graphene. Thermograivmetric analysis (TGA) have shown that the thermal stability of PVK/graphene (0.5 wt%) is maximum improved by -76 degrees C compared to neat PVK, when 20 wt% weight loss is taken as a point of comparison. Ultraviolet (UV) and photoluminescence (PL) studies established the charge transfer from polymer chains to the graphene platelets. Dielectric measurements have shown the maximum improvement (87%) in dielectric constant (ε) with 1 wt% graphene loading. The variation of ac conductivity (σ) with frequency (ψ) confirmed the insulating behavior of PVK/graphene nanocomposites possessing high dielectric constant.

Size Effect of Ordered Mesoporous Carbon Nanospheres for Anodes in Li-Ion Battery.

The present work demonstrates the application of various sizes of ordered mesoporous carbon nanospheres (OMCS) with diameters of 46-130 nm as an active anode material for Li-ion batteries (LIB). The physical and chemical properties of OMCS have been evaluated by performing scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption analysis; small-angle scattering system (SAXS) and X-ray diffraction (XRD). The electrochemical analysis of using various sizes of OMCS as anode materials showed high capacity and rate capability with the specific capacity up to 560 mA·h·g-1 at 0.1 C after 85 cycles. In terms of performance at high current rate compared to other amorphous carbonaceous materials; a stable and extremely high specific capacity of 240 mA·h·g-1 at 5 C after 15 cycles was achieved. Such excellent performance is mainly attributed to the suitable particle size distribution of OMCS and intimate contact between OMCS and conductive additives; which can be supported from the TEM images. Results obtained from this study clearly indicate the excellence of size distribution of highly integrated mesoporous structure of carbon nanospheres for LIB application.

MoS2-MWCNT hybrids as a superior anode in lithium-ion batteries.

Molybdenum disulfide (MoS(2))-multiwalled carbon nanotube (MWCNT) hybrids have been prepared by simple dry grinding. Excellent initial charge capacity (1214 mA h g(-1)) and ~85% retention after 60 discharge-charge cycles at different current densities (100-500 mA g(-1)) make MoS(2)-MWCNT (1 : 1) hybrids a superior anode in Li-ion batteries.

Reinforcement of ball shaped MoS2 nanoparticles in epoxy resin.

The present work involves the synthesis of molybdenum disulfide (MoS2) nanoparticles by annealing the precursor obtained from simple reflux method. XRD, FESEM and HRTEM confirmed the formation of 2H-MoS2 with ball shaped particles, where some of them possess coalesced dumbbell morphology. The reinforcement of polysulphide modified epoxy resin (PSER) by MoS2 with varying amounts from 0.150 to 0.200 wt% provides unique combination of the improved thermal stability, tribological and mechanical properties. XRD studies indicate interaction between the sulphur containing nanoparticles and the epoxy resin. Maximum improvements in tensile strength (440%) and toughness (534%) are observed with ball shaped MoS2 nanoparticles (0.150 wt%)/PSER composite. Also the coefficient of friction and wear resistance show improvements of 60 and 78% respectively for 0.175 wt% loading in PSER compared to the neat resin matrix. Thermal stability is found to be improved maximum by 23 degrees C, when 5% weight loss is taken as a point of comparison. Similar studies on synthetic microcrystalline MoS2 filled PSER show that improvements in all these properties are very inferior.