Search

The self-powered PVP-Co@C nanofibers/n-GaAs heterojunction photodetector (HJPD) was fabricated by electrospinning of the nanofibers onto GaAs. An excellent rectification ratio of 6.60 × 106 was obtained from I – V measurements of the device in the dark. The I – V measurements of the fabricated device under 365 nm, 395 nm and 850 nm lights, as well as I – V measurements in visible light depending on the light intensity, were performed. The HJPD demonstrated excellent photodetection performance in terms of a good responsivity of ∼225 mA W−1 (at −1.72 V) and at zero bias, an impressive detectivity of 6.28 × 1012 Jones, and a high on/off ratio of 8.38 × 105, all at 365 nm wavelength. In addition, the maximum external quantum efficiency and NPDR values were 3495% (V = −1.72 V) and 2.60 × 1010 W−1 (V = 0.0 V), respectively, while the minimum NEP value was ∼10−14 W.Hz−1/2 for 365 nm at V = 0.V volts. The HJPD also exhibited good long-term stability in air after 30 d without any encapsulation. [ABSTRACT FROM AUTHOR]

Carbon fibers were successfully fabricated via the electrospinning technique, followed by stabilizing and carbonizing electrospun PAN fibers. A wide range of analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), vibrating sample magnetometer (VSM) techniques, and Hall effect were performed to study of the effect of carbonization temperature on the physical and chemical characterization of carbon fibers. The SEM images of the PAN precursor exhibit a smooth outer surface, after the stabilization and carbonization process, along with a broken fiber at higher carbonization temperature about 1400 °C. Morphological characterization based on the recorded TEM images of carbonized fibers at 1000 °C and 1400 °C, showed that the obtained morphology can be classified as fiber structures, where their diameters ranged from 196 to 331 nm. The XRD patterns of PAN-based carbon fibers confirm the structural changes from linear structure into a graphite-like structure. The DRS study indicates the possible π–π*/σ–π* and n–π* transitions. The presence of the surface functional groups and different trapped radiative recombination on the emission bands is confirmed by the PL. VSM results shows the weak ferromagnetic nature of the carbon fibers. [ABSTRACT FROM AUTHOR]

Mn:CeO2/PVP nanofibers were prepared via a simple electrospinning technique with heat treatment at 500°C. X-ray diffraction patterns revealed the formation of a face-centered cubic structure for pure and Mn:CeO2 nanofibers. Whole powder pattern modeling was applied to the x-ray diffraction data for pure and Mn:CeO2 nanofibers to determine the microstructure parameters (the crystalline domain size and the size distribution). The effect of Mn doping on the morphology features of the prepared nanofibers was assessed from the scanning electron microscopy (SEM) image analysis. The SEM images showed random fibers with no distinct alignment, with average fiber diameters of about 80–150 nm after calcination. FT-IR spectra of the Mn0.05Ce0.95O2 nanofibers showed stretching vibrations corresponding to Mn-O and Ce-O bonds. The optical absorption of pure and Mn:CeO2 nanofibers was studied using diffuse reflectance spectroscopy. The optical band gap was found to increase with increased Mn doping, which can be attributed to the quantum confinement effect. [ABSTRACT FROM AUTHOR]

In this study, nanocrystalline ZnO-SnO mixed metal oxide powder was prepared by co-precipitation using Zn(CHCOO)∙2HO and SnCl∙5HO as precursor materials. The powder was characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Williamson-Hall method was used to evaluate the micro structural parameters of ZnO-SnO such as crystallite sizes and lattice strain. The photoluminescence property of the sample was studied at different temperatures (10-300 K). Results showed that the emission intensity decreases with temperature increasing. The photocatalytic activity at the gas-solid interface was assessed by monitoring the degradation of nitrogen oxides, a major atmospheric pollutant. The results show that the nanocrystalline ZnO-SnO mixed metal oxide powder exhibits higher and more stable photocatalytic activity against photocorrosion than ZnO alone. Graphical abstract: [ABSTRACT FROM AUTHOR]