Revelation of graphene-Au for direct write deposition and characterization

Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties

Development of Graphene Nanoplatelets Reinforced Shape Memory Polyurethane and Their DMA Studies

Shape memory nanocomposites have been synthesized using ether type shape memory polyurethane (SMPU) and graphene nanoplatelets (GNPs). A twin screw co-rotating microcompounder with a back flow channel has been employed to ensure proper dispersion of GNPs in the polymer matrix. Four compositions of GNPs in SMPU have been prepared. Morphology of fractured nanocomposites reveals uniform dispersion of graphene in SMPU. The dynamic-thermo-mechanical properties of nanocomposites at 0.1 and 10 Hz have been studied. Addition of 1 phr GNPs increases storage modulus of SMPU from 2.8 to 3.73 GPa and the value of tan δ peak has been decreased from 0.81 to 0.53. The GNPs in SMPU matrix influence shape recovery which improves with the addition of GNPs with in experimental range

Enhancing Light Harvesting by Hierarchical Functionally Graded Transparent Conducting Al-doped ZnO Nano- and Mesoarchitectures

A functionally graded Al-doped ZnO structure is presented which combines conductivity, visible transparency and light scattering with mechanical flexibility. The nano and meso-architecture, constituted by a hierarchical, large surface area, mesoporous tree-like structure evolving in a compact layer, is synthesized at room temperature and is fully compatible with plastic substrates. Light trapping capability is demonstrated by showing up to 100% improvement of light absorption of a low bandgap polymer employed as the active layer.Comment: 21 pages, 6 figures, submitted to Solar Energy Materials and Solar Cell

Synthesis and characterization of Pt/graphene-CNTs electrocatalyst for direct methanol fuel cell

Abstract In the present work we report a facile method for the synthesis of Pt nanoparticles supported reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) nanocomposite by an in-situ chemical reduction. The incorporation of MWCNTs to rGO leads to decrease in agglomeration between rGO sheets due to π -π interactions and higher loading of Pt nanoparticles. In this process, a mixture of exfoliated graphene oxide, CNTs and chloroplatinic acid was treated with a mixture of hydrazine hydrate and ammonium hydroxide at 95° C in an oil bath for 1 h. Pt nanoparticles of 4-6 nm size were homogeneously dispersed on rGO-CNTs nanocomposite as revealed by TEM analysis. Cyclic voltammetry measurements depict an anodic current density of 11.74 mA/cm 2 that could be obtained using Pt/rGO-CNTs catalyst and 6.2 mA/cm 2 using Pt/rGO catalyst during methanol oxidation, indicating that the catalytic activity of Pt/rGO-CNTs catalyst is almost 2 times higher than that of Pt/rGO catalyst. The electrochemical stability of Pt/rGO-CNTs catalyst was also found to be much higher as compared with that of Pt/rGO catalyst. Thus, Pt/rGO-CNTs catalyst has the potential to be used in the preparation of a promising anode material for direct methanol fuel cell

High yield synthesis of electrolyte heating assisted electrochemically exfoliated graphene for electromagnetic interference shielding applications

Herein, we demonstrate a facile one pot synthesis of graphene nanosheets by electrochemical exfoliation of graphite. In the present study, we report a significant increase in the yield of graphene by electrolyte heating assisted electrochemical exfoliation method. The obtained results of heating assisted electrochemically exfoliated graphene (utilizing H2SO4 + KOH + DW) synthesis clearly exhibit that the yield increases similar to 4.5 times i.e. from similar to 17% (room temperature) to similar to 77% (at 80 degrees C). A plausible mechanism for the enhanced yield based on lattice expansion and vibration of intercalated ions has been put forward and discussed in details. The quality of graphene was examined by Raman, XPS, FTIR, AFM, SEM, TEM/HRTEM and TGA techniques. The Raman as well as morphogenesis results confirm the quality of the graphene nanosheets. We have used this graphene as electromagnetic interference shielding material where a comparatively large quantity of graphene is required. This graphene exhibits enhanced shielding effectiveness (46 dB at 1 mm thickness of stacked graphene sheets in frequency region 12.4 to 18 GHz) as compared to conventional electromagnetic interference shielding materials, which is greater than the recommended limit (similar to 30 dB) for techno-commercial applications. Thus the present work is suggestive for future studies on enhancement of yield of high quality graphene by proposed method and the use of synthesized graphene in electromagnetic interference shielding and other possible applications

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Multiphase TiO2 nanostructures: a review of efficient synthesis, growth mechanism, probing capabilities, and applications in bio-safety and health

This review article provides an exhaustive overview of the efficient synthesis, growth mechanism and research activities that mainly concern an assortment of multiphase TiO2 nanostructures and their structural, morphological, optical and biological properties co-relations. First, a systematic review is provided for the state-of-art and synthetic mechanisms utilized to generate these nanostructured systems. A range of remarkable photoactive characteristics with respect to the effects of the structural phases as well as morphogenesis are then briefly covered and organized into sections presenting the nanostructures' photo-luminescence and photo-catalysis properties. A plausible mechanism for their nano-bio interaction is also reviewed, and clearly shows their potential in bio-safety and health applications. These studies should inspire researchers involved in both fundamental and application based research to pursue further developments in multiphase TiO2 nanostructures

Multiphase TiO2 nanostructures: a review of efficient synthesis, growth mechanism, probing capabilities, and applications in bio-safety and health

This review article provides an exhaustive overview of the efficient synthesis, growth mechanism and research activities that mainly concern an assortment of multiphase TiO2 nanostructures and their structural, morphological, optical and biological properties co-relations. First, a systematic review is provided for the state-of-art and synthetic mechanisms utilized to generate these nanostructured systems. A range of remarkable photoactive characteristics with respect to the effects of the structural phases as well as morphogenesis are then briefly covered and organized into sections presenting the nanostructures' photo-luminescence and photo-catalysis properties. A plausible mechanism for their nano-bio interaction is also reviewed, and clearly shows their potential in bio-safety and health applications. These studies should inspire researchers involved in both fundamental and application based research to pursue further developments in multiphase TiO2 nanostructures