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Vengatesan, M. R.,Shen, Tian-Zi,Alagar, M.,Song, Jang-Kun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.1
<P>We report a cost effective and easy chemical reduction method for exfoliated individual graphene oxide (GO) and GO paper using p-toluene sulfonic acid (PTSA) under mild conditions. Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), thermo gravimetric analysis (TGA) and transmission electron microscopy (TEM) analysis were performed to investigate the quality of GO reduction. Data resulting from the spectral analysis suggest that the reduction method using PTSA is an efficient method to remove oxygen functionalities in the GO and also as an alternative to commonly used reducing agents. We also fabricated chemically reduced GO (RGO) film from GO film using this method. The RGO film exhibits an electrical conductivity of about 10587 Sm-1. These results suggest that this method is very useful for the reduction of GO and GO film or paper using PTSA in a solution process for flexible electronics due to its facile, efficient and cost-effective features.</P>
Binary Cu/ZnO decorated graphene nanocomposites as an efficient anode for lithium ion batteries
Liyamol Jacob,K. Prasanna,M.R. Vengatesan,P. Santhoshkumar,이창우,Vikas Mittal 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-
Binary metal/metal oxide doped graphene nanocomposites have received wide attention as an effective anode material in Li-ion batteries. The binary composition metal/metal oxide improves the storage space and the conductivity of the electrode. The doped graphene enhances the structural and electronic properties of the electrode. In the present work, we report a Cu/ZnO hybrid nanoparticle-decorated graphene nanocomposite as an advanced anode material for the high-performance Li-ion batteries. Three different compositions of the hybrid Cu/ZnO/graphene nanocomposites have been synthesized by changing the concentration of Cu precursors in the hybrid. The nanocomposite of 0.05 M Cu precursor and 0.1 M ZnO precursor shows higher surface area (SBET = 168.7 g/m2) and excellent electrochemical results. X-ray photoelectron spectroscopy (XPS) analysis revealed that the Cu nanoparticle exists in +2 oxidation state on the ZnO lattice with the graphene nanostructure. Transmission electron microscopy (TEM) analysis shows the distribution of Cu/ZnO nanoparticles over the graphene sheets with a size of around 10–50 nm. From the electrochemical analysis, we inferred that the hybrid possesses a stable and specific capacity of 630 mAh g−1 at a current rate of 100 mA g−1 with almost 95% capacity retention for up to 100 cycles. To highlight the importance of binary Cu/ZnO doped graphene nanocomposites, their respective base namely, ZnO/graphene and Cu/graphene composites have also been studied.
Wijewardhana, K. Rohana,Shen, Tian-Zi,Vengatesan, M.R.,Kim, Joosung,Lee, Hyoyoung,Song, Jang-Kun Elsevier 2017 Carbon Vol.119 No.-
<P>Transport, relocation, and self-assembly of nano and microparticles in colloidal systems are highly demanded in nanotechnology, photonics, microfluidics, and biotechnology; topological charges can provide an effective means for these purposes. We report that crumpled two-dimensional (2D) graphene oxide (GO) particle sheets in nematic fields can serve as a nest for complicated topological defect loops, which, in turn, provide mobility and inter-adhesiveness to the GO particles. The application of electric fields actuated the GO particles orthogonally, inducing their coalescence into large radial clusters upon absorption of other GO particles. In contrast, in the isotropic phase, where no topological defects existed, the GO particles electrostatically repelled each other owing to the presence of surface charges with equal sign. We also demonstrate that predesigned shallow surface trenches on a substrate can anchor seed GO particles, which attract other GO particles to create a macroscopic structure along the trench. (C) 2017 Elsevier Ltd. All rights reserved.</P>