Vipin Jain; Anil Kumar; Ajay Dhar
Abstract
Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, ...
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Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, a novel chemical synthesis method has been adopted for the in-situ synthesis of aluminium-graphene (Al-Gr) nanocomposite powders with varying compositions using graphene oxide (GO) as the precursor. The pure aluminium powder was initially cryomilled to refine the crystallite size. Subsequently, Al-reduced graphene (Al-Gr) nanocomposite powders were synthesized employing different volume proportions of GO (referred as 0.5, 2, 4, and 6 ml) dispersed in deionized water. The synthesized nanocomposite powders were ball milled followed by consolidation using spark plasma sintering under the optimized conditions. The nanocomposite powder as well as SPSed samples were characterized using X-ray diffraction (XRD), Raman Spectroscopy and electron microscopy. Scanning electron microscopy (SEM) studies of nanocomposite powders have depicted wrinkled structure typical of reduced graphene. Raman spectra have shown regular D, G, 2D and D+G bands and a modulated 2D peak having intensity significantly less than the G peak was observed for the nanocomposite powders confirming multilayered graphene is synthesized. The graphene wrinkles were determined in the size of 100 nm or more. Microhardness of SPS sintered nanocomposites is found progressively increased with the increasing content of reduced graphene with up to 58% improvement over pure Al was observed for the maximized GO content depicting potential for energy efficient high strength applications. The synthesized Al-graphene nanocomposites are novel in terms of an innovative, indigenously developed and scalable to bulk synthesis approach based on in-situ chemical synthesis route adopted. Copyright © 2017 VBRI Press.
Mahima Khandelwal; Anil Kumar
Abstract
N-doped graphene has been synthesized by the reduction of graphene oxide (GO) using 2-aminoisobutyric acid (AIB) as a reducing agent (N-GrAIB) under mild experimental conditions in aqueous medium. The reduction of GO was indicated by a change in its optical absorption as well as by its Raman spectrum ...
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N-doped graphene has been synthesized by the reduction of graphene oxide (GO) using 2-aminoisobutyric acid (AIB) as a reducing agent (N-GrAIB) under mild experimental conditions in aqueous medium. The reduction of GO was indicated by a change in its optical absorption as well as by its Raman spectrum and 13C solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) studies. The latter two techniques also confirmed the doping of N. N-GrAIB exhibited fairly high conductivity (6.3 S/cm), high specific capacitance (228 F/g at 1 A/g) with good cycling stability for 1000 charge-discharge cycles, high coulombic efficiency (100-101%) and high energy density of 20.26 Wh/kg at a power density of 400 W/kg. The present work shows that this environmental benign N-doped graphene (N-GrAIB) could be a promising electrode material for supercapacitor applications. Copyright © 2016 VBRI Press
Mahima Khandelwal; Anil Kumar; Richa Baronia; Shraddha Tiwari; Avanish K. Srivastava; Surinder P. Singh; Sunil K. Singhal
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 ...
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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/cm2 that could be obtained using Pt/rGO-CNTs catalyst and 6.2 mA/cm2 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. Copyright © 2016 VBRI Press
