Avanish K. Srivastava; Bhumika Samaria; Smita Soni; Virendra S Chauhan; Jitendra Singh; Rajesh K Shukla; Anuj Shukla; Narendra Kumar
Abstract
In the ongoing search for newer materials for microwave absorption applications, the graphene merits a special consideration owing to its outstanding mechanical, thermal and electrical properties. Here, we report investigation on microwave absorption properties of Fe-Co oxide- thermally exfoliated graphene ...
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In the ongoing search for newer materials for microwave absorption applications, the graphene merits a special consideration owing to its outstanding mechanical, thermal and electrical properties. Here, we report investigation on microwave absorption properties of Fe-Co oxide- thermally exfoliated graphene oxide (Fe-Co oxide-TEGO) composite in a frequency range of 8-18 GHz. Fe-Co oxide was synthesized by thermal decomposition of Fe-Co oxide/aniline- formaldehyde copolymer at 900 0C in air. Fe-Co oxide-TEGO hybrid was prepared by physical mixing of Fe-Co oxide and TEGO. Thereafter, hybrid was characterized using scanning electron microscope, energy dispersive X-ray, Fourier transform infrared spectrometer and X-ray diffractrometer. Thereafter, Fe-Co oxide-TEGO composites were prepared by intermixing in different weight % in PU (polyurethane) resin and their electromagnetic and microwave absorption properties were studied. The effect of varying the weight % of Fe-Co oxide in Fe-Co oxide-TEGO composite on electromagnetic properties was also studied. The absorption bandwidth of 3.5 GHz (8.5-12.0 GHz, X-band) and 5.0 GHz (13.0-18.0 GHz, Ku -band) has been achieved using Fe-Co oxide-TEGO composite (50 wt%) with 2.2 and 1.6 mm thickness, respectively. Microwave absorption studies show Fe-Co oxide- TEGO composite as a potential candidate for microwave absorption applications. Copyright© 2018 VBRI Press.
Bhumika Samaria; Avanish K. Srivastava; Virendra S Chauhan; Jitendra Singh; Smita Soni; Manoj K Dhaka; Rajesh K Shukla; Anuj Shukla; Narendra Kumar
Abstract
The discovery of graphene and subsequent development of graphene-based nanocomposites in different matrices including that in polymer is an important addition in the area of nanoscience and technology. This work deals with the studies on the dielectric properties of the nanocomposites of graphite, graphite ...
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The discovery of graphene and subsequent development of graphene-based nanocomposites in different matrices including that in polymer is an important addition in the area of nanoscience and technology. This work deals with the studies on the dielectric properties of the nanocomposites of graphite, graphite oxide (GO) and thermally exfoliated graphene oxide (TEGO) in epoxy matrix. GO was synthesized using modified Hummers method which on heat treatment at ~300 0C resulted into formation of graphene oxide termed as TEGO. The synthesized GO and TEGO were characterized using scanning electron microscope, energy dispersive X-ray, Fourier transform infrared spectrophotometer, Raman spectrometer, X-ray diffractometer, UV-Vis spectrometer, CHNSO analyzer, surface area analyzer, and dc electrical conductivity. Composites using graphite powder (GP), GO and TEGO individually were prepared in epoxy resin. The dielectric (dielectric permittivity, dielectric loss tangent) properties of composites were studied in frequency range of 8 - 12 GHz. Dielectric tangent loss (tande) vary from 0.02 for GP to 0.35 for TEGO. The effect of addition of GP to GO and TEGO composite on dielectric properties was investigated. The order of tandevalues of composites is: TEGO > GP-TEGO > GP-GO> GO >GP. TEGO composite showed significant dielectric loss among the reported composites. The results thus indicate TEGO as filler for epoxy based composites to afford specific dielectric properties, especially as an alternative of much more expensive carbon nanotubes. Copyright © 2018 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
