Bishweshwar Pant

Synthesis and characterization of reduced graphene oxide decorated with CeO2-doped MnO2 nanorods for supercapacitor applications

A novel and efficient CeO2-doped MnO2 nanorods decorated reduced graphene oxide (CeO2-MnO2/RGO) nanocomposite was successfully synthesized via hydrothermal method. The growth of the CeO2 doped MnO2 nanorods over GO sheets and reduction of GO were simultaneously carried out under hydrothermal treatment. The morphology and structure of as-synthesized nanocomposite were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which revealed the formation of CeO2-MnO2 decorated RGO nanocomposites. The electrochemical performance of as-prepared CeO2-MnO2/RGO nanocomposites as an active electrode material for supercapacitor was evaluated by cyclic voltammetry, charge-discharge, and electrochemical impedance spectroscopy (EIS) methods in 2M alkaline medium. The obtained results revealed that as-synthesized CeO2-MnO2/RGO nanocomposite exhibited higher specific capacitance (648F/g) as compared to other formulations (MnO2/RGO nanocomposites: 315.13 F/g and MnO2 nanorods: 228.5 F/g) at the scan rate of 5mV/s. After 1000 cycles, it retained ∼90.4%, exhibiting a good stability. The high surface area, enhanced electrical conductivity, and good stability possess by the nanocomposite make this material a promising candidate to be applied as a supercapacitor electrode.

Novel magnetically separable silver-iron oxide nanoparticles decorated graphitic carbon nitride nano-sheets: A multifunctional photocatalyst via one-step hydrothermal process

Development of photocatalytic materials with magnetic and antibacterial properties is highly desirable in wastewater treatment. In this study, a novel magnetically separable silver-iron oxide nanoparticles (Ag-Fe3O4 NPs) decorated graphitic carbon nitride (g-C3N4) nanocomposite via hydrothermal treatment has been presented for the multifaceted applications. The physiochemical properties of the as-synthesized ternary nanocomposite were characterized by the field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) studies. The experimental results showed that loading of Ag on Fe3O4/g-C3N4 nanocomposite significantly improved the catalytic activity of the composite material in terms of photocatalytic degradation of methylene blue (Mdestruction of Escherichia coli (E. coli) bacteria. More importantly, the as-synthesized silver-iron oxide nanoparticles decorated graphitic carbon nitride (Ag-Fe3O4/g-C3N4) nanocomposite catalyst could be recovered by an applied external magnet and reused without the loss of photocatalytic activity. The obtained results showed that the synthesized material has potential as an economically friendly photocatalyst for environmental and energy applications.

Biocompatible and photoluminescent keratin/poly(vinyl alcohol)/carbon quantum dot nanofiber: A novel multipurpose electrospun mat

Carbon quantum dots (C-dots) triggered photoluminescent keratin/poly(vinyl alcohol) (PVA)/C-dots nanofibers (NFs) with optical transparency and biocompatibility were prepared by an electrospinning process. The synthesized NFs were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, and spectrofluorometer. C-dots are capable of emitting excitation dependent photoluminescence (PL) emission spectra at room temperature and are nontoxic at reasonably high concentrations. Optically transparent keratin/PVA/C-dots NFs were found to exhibit excitation dependent PL emission at the wavelengths of 488, 535, and 625 nm during excitation at the wavelengths of 360, 480, and 545 nm, respectively, similar to the C-dots. In vitro cytotoxicity tests against NIH-3T3 cell lines revealed a good biocompatible nature of keratin/PVA/C-dots. The results indicated that the fabricated composite NFs mat not only exhibited a well preserved quantum confinement effect of the C-dots along with its transparency but also showed biocompatibility in the living cell environment.

Carbon nanofibers wrapped with zinc oxide nano-flakes as promising electrode material for supercapacitors

A combination of electrospinning technique and hydrothermal process was carried out to fabricate zinc oxide nano-flakes wrapped carbon nanofibers (ZnO/CNFs) composite as an effective electrode material for supercapacitor. The morphology of the as-synthesized composite clearly revealed that the carbon nanofibers were successfully wrapped with ZnO nano-flakes. The electrochemical performance of the as-synthesized nanocomposite electrode was evaluated by the cyclic voltammetry (CV), galvanostatic charge-discharge (GDC), and electrochemical impedance spectroscopy (EIS), and compared with the pristine ZnO nanofibers. It was found that the composite exhibited a higher specific capacitance (260 F/g) as compared to pristine ZnO NFs (118 F/g) at the scan rate of 5 mV/s. Furthermore, the ZnO/CNFs composite also exhibited good capacity retention (73.33%). The obtained results indicated great potential applications of ZnO/CNFs composite in developing energy storage devices with high energy and power densities. The present work might provide a new route for utilizing ZnO based composites for energy storage applications.

Electrospun salicylic acid/polyurethane composite nanofibers for biomedical applications

ABSTRACT Salicylic acid (SA)/polyurethane (PU) composite nanofiber mats were fabricated by introducing SA in PU solution during the electrospinning process. Cell viability assays showed that the as-prepared composite nanofibers had a good biocompatibility. Further, the composite mats showed good antibacterial performance against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Easy fabrication, good mechanical properties, good biocompatibility as well as the antibacterial activity of PU nanofibers containing SA indicated their significant promise for a variety of potential medical applications such as tissue engineering, wound healing, and drug delivery system. GRAPHICAL ABSTRACT