Transition-metal compounds (TMCs) such as oxides, hydroxides, and sulfides are well-known pseudocapacitive materials whose capacitance has been shown to improve by combining them with different carbon nanostructures (CNSs). Here, we report a systematic investigation on the influence of six different CNSs: single-walled carbon nanotubes (SWCNTs), functionalized and multiwalled carbon nanotubes, graphene oxide (GO), reduced GO (rGO), and graphene nanoplatelets on Ni­(OH)2 nanostructures, focusing on their electrochemical properties for potential use as electrode materials in supercapacitors. Uniformly distributed Ni­(OH)2 nanohexagons (approximately 30–35 nm in size) were found to be well attached to the surfaces of these CNSs. Among the studied CNSs, rGO appeared to be the best as its composite with Ni­(OH)2 exhibited the highest specific capacitance of 2306 F/g at 3 A/g along with 81.4% capacity retention after 5000 cycles. The SWCNT/Ni­(OH)2 composite showed the second best performance, with all other composites showing much lower performances. The lower charge transfer resistance and higher ion diffusion coefficient of the rGO/Ni­(OH)2 composite, compared to those of all other composites of Ni­(OH)2, have been identified as the reason for its improved performance. These results may find far-fetching significance in designing TMC-nanostructure-based electrodes modified with CNSs for supercapacitors.

No abstract

The effect of an 8 MeV electron-beam on the structural, optical and dielectric properties of polystyrene films has been investigated respectively by means of Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy and electrical impedance (LCR) analysis over a radiation dose in the range of 50-250 kGy using a Microtron accelerator. The FTIR spectral analysis shows no change in the overall structure of the irradiated polystyrene films, except a minor change in the intensity of a few peaks in the FTIR spectrum, indicating that polystyrene is resistant to electron-beam irradiation over the range of radiation doses investigated. The optical band gap analysis using the UV-VIS absorption spectra of the polystyrene shows a small decrease in the optical band gap (E g ) and the activation energy with an increase in electron doses. Further, the dielectric measurements over a frequency range of 100 Hz to 1 MHz for the electron-beam-irradiated polystyrene films show that both the dielectric constant and the dielectric loss increase with an increase in electron radiation dose, which may be ascribed to the formation of defect sites in the band gap of polystyrene as a consequence of molecular chain scission in the polymer films upon irradiation.

Post-irradiation studies have been carried out to elucidate the effects of electron beam irradiation on the structural, optical, dielectric, and thermal properties of high-density polyethylene (HDPE) films. The experimental results showed that both the optical band gap and activation energy of HDPE films decreases with an increase in the doses of electron radiation. The electrical measurements showed that dielectric constant and the ac conductivity of HDPE increases with an increase in the dose of electron radiation. The thermal analysis carried out using DSC and TGA revealed that the melting temperature, degree of crystallinity, and thermal stability of the HDPE films increased, obviously, due to the predominant cross-linking reaction following high doses of electron irradiation.

Photofission cross-section of 238 U was measured using bremsstrahlung radiation energy 7.4-9.0 MeV with energy step of 0.4 MeV by employing Lexan polycarbonate film as solid state nuclear track detector (SSNTD). The photon intensity from the Microtron accelerator at a distance of 15 cm from the bremsstrahlung converter (tantalum target) facility was estimated to be 10 10 photons/sec using the code EGS-4. In this paper, details of the fission fragment angular distribution measurements of 238 U target using Lexan polycarbonate have been discussed. The photofission cross-section was calculated using the angular distribution of fission fragments and the results were compared with those obtained using the code EMPIRE-II and various barrier parameters of the RIPL-1, RIPL-2 libraries and with the new analytical fission barrier formula based on the Hugenholtz-Van Hove theorem. The present experimental measurements were in good agreement with the results obtained from the Empire-II code predictions for potential parameter taken from RIPL-1 and a newly developed analytical fission barrier formula.

No abstract

No abstract

Polymer electrolytes based on polyethylene oxide complexes with conducting polyaniline (PANI) and a salt of sodium chlorate has been prepared in different weight percentage ratios. The complexation is confirmed by FTIR spectroscopy and morphology study by employing SEM. AC conductivity measurements are carried out by using LCR Q meter at room temperature. Electrochemical cell parameters for battery applications at room temperature are also determined. The composites PP5, N3 and N4 show good conductivity which is due to ionic polarization and electrode polarization. Among all these composites N3 shows highest conductivity which is also well understood through the SEM studies. PP5 shows more conductivity than all the other composites except N3 as because PANI when mixed with PEO gives more feasibility of matrix's for fast mobility of ions through it easily. The samples are fabricated for battery applications in configuration of Na: (PEO: PANI: NaClO4): (I2 + C + sample) and their experimental data are measured using the Wagner polarization technique.