Surajit Konwer

Bio: Surajit Konwer is an academic researcher from Dibrugarh University. The author has contributed to research in topics: Polyaniline & Fourier transform infrared spectroscopy. The author has an hindex of 10, co-authored 19 publications receiving 425 citations. Previous affiliations of Surajit Konwer include Tezpur University.

Studies on Conducting Polypyrrole/Graphene Oxide Composites as Supercapacitor Electrode

Abstract: An electrode material based on polypyrrole (PPy) doped with graphene oxide (GO) sheets was synthesized via in situ polymerization of pyrrole in the presence of GO in various proportions (5% and 10%). The synthesized samples were characterized by Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and electrical conductivity measurements. FTIR spectroscopy and XRD revealed the interaction between GO and PPy. The direct-current (DC) electrical conductivity (75.8 S/cm) of the prepared composites was dramatically enhanced compared with pure PPy (1.18 S/cm). High specific capacitance of PPy/GO composite of 421.4 F/g was obtained in the potential range from 0 V to 0.50 V at 2 mA compared with 237.2 F/g for pure PPy by galvanostatic charge–discharge analysis. Incorporation of GO into the PPy matrix has a pronounced effect on the electrical conductivity and electrochemical capacitance performance of PPy/GO nanocomposites.

Graphene oxide-filled conducting polyaniline composites as methanol-sensing materials

Abstract: Polyaniline/graphene oxide (PANI/GO) composites were prepared by polymerization of aniline monomer in the presence of GO under acidic conditions. The synthesized samples were characterized by Fourier transform infra red spectroscopy, ultraviolet–visible absorption, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The direct current electrical conductivity of the composite was calculated by a four-probe technique. It is found that the conductivity dramatically increased to 241 S m−1 for PANI/GO (5 wt%) composite at 110 °C compared to pure PANI (7.5 S m−1). The composite material was investigated as a methanol vapour sensor and compared with pure PANI. The methanol-sensing characteristics of the prepared composite was monitored by measuring the change in electrical resistivity on exposure to methanol vapour at different concentrations. The resistivity of PANI increases on exposure to methanol vapour because of strong hydrogen bonding between methanol with the polymer chain. A density functional theory study was carried out to verify the proposed concept of hydrogen bonding between the polymer chains and methanol. The presence of GO in PANI/GO composite increases the sensitivity towards methanol as compared with the pure PANI.

Enantiomeric Recognition and Separation by Chiral Nanoparticles

Abstract: Chiral molecules are stereoselective with regard to specific biological functions. Enantiomers differ considerably in their physiological reactions with the human body. Safeguarding the quality and safety of drugs requires an efficient analytical platform by which to selectively probe chiral compounds to ensure the extraction of single enantiomers. Asymmetric synthesis is a mature approach to the production of single enantiomers; however, it is poorly suited to mass production and allows for only specific enantioselective reactions. Furthermore, it is too expensive and time-consuming for the evaluation of therapeutic drugs in the early stages of development. These limitations have prompted the development of surface-modified nanoparticles using amino acids, chiral organic ligands, or functional groups as chiral selectors applicable to a racemic mixture of chiral molecules. The fact that these combinations can be optimized in terms of sensitivity, specificity, and enantioselectivity makes them ideal for enantiomeric recognition and separation. In chiral resolution, molecules bond selectively to particle surfaces according to homochiral interactions, whereupon an enantiopure compound is extracted from the solution through a simple filtration process. In this review article, we discuss the fabrication of chiral nanoparticles and look at the ways their distinctive surface properties have been adopted in enantiomeric recognition and separation.

Highly Compression‐Tolerant Supercapacitor Based on Polypyrrole‐mediated Graphene Foam Electrodes

Abstract: Deformation-tolerant devices are vital for the development of high-tech electronics of unconventional forms. In this study, a highly compressible supercapacitor has been fabricated by using newly developed polypyrrole-mediated graphene foam as electrode. The assembled supercapacitor performs based on the unique and robust foam electrodes achieves superb compression tolerance without significant variation of capacitances under long-term compressive loading and unloading processes.

Nanostructured conductive polypyrrole hydrogels as high-performance, flexible supercapacitor electrodes

Abstract: Electrochemically active conducting polymers are an important class of materials for applications in energy storage devices such as batteries and supercapacitors, owing to their advantageous features of unique three-dimensional (3D) porous microstructure, high capacitive energy density, scalable synthesis and light weight. Here, we synthesized a nanostructured conductive polypyrrole (PPy) hydrogel via an interfacial polymerization method. The simple synthesis chemistry offers the conductive hydrogel tunable nanostructures and electrochemical performance, as well as scalable processability. Moreover, the unique 3D porous nanostructure constructed by interconnected polymer nanospheres endows PPy hydrogels with good mechanical properties and high performance acting as supercapacitor electrodes with a specific capacitance of ∼380 F g−1, excellent rate capability, and areal capacitance as high as ∼6.4 F cm−2 at a mass loading of 20 mg cm−2.

Carbon-based supercapacitors for efficient energy storage

Abstract: The advancement of modern electronic devices depends strongly on the highly efficient energy sources possessing high energy density and power density. In this regard, supercapacitors show great promise. Due to the unique hierarchical structure, excellent electrical and mechanical properties, and high specific surface area, carbon nanomaterials (particularly, carbon nanotubes, graphene, mesoporous carbon and their hybrids) have been widely investigated as efficient electrode materials in supercapacitors. This review article summarizes progress in high-performance supercapacitors based on carbon nanomaterials with an emphasis on the design and fabrication of electrode structures and elucidation of charge-storage mechanisms. Recent developments on carbon-based flexible and stretchable supercapacitors for various potential applications, including integrated energy sources, self-powered sensors and wearable electronics, are also discussed.