Carbon/CuO nanosphere-anchored g-C3N4 nanosheets as ternary electrode material for supercapacitors

Novel electrode materials for supercapacitors comprised of carbon and copper oxide (CuO) nanospheres on graphitic carbon nitride (g-C3N4) nanosheets, denoted as C/CuO@g-C3N4 are self-assembled via a one-step co-pyrolysis decomposition method. The pure g-C3N4 and C/CuO@g-C3N4 were confirmed by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), N-2 adsorption/desorption studies and Fourier-transform infrared spectroscopy (FTIR). The specific capacitance was 247.2 F g(-1) in 0.5 M NaOH at a current density of 1 Ag-1, and more than 92.1% of the capacitance was retained after 6000 cycles. The property enhancement was ascribed to the synergistic effects of the three components in the composite. These results suggest that C/CuO@g-C3N4 possessed an excellent cyclic stability with respect to their capacity performance as electrode materials

Influence of substrate bias voltage on crystallographic structure, optical and electronic properties of Al/(Ta2O5)(0.85)(TiO2)(0.15)/p-Si MIS Schottky barrier diodes fabricated by dc magnetron sputtering

Thin films of (Ta2O5)(0.85)(TiO2)(0.15) were prepared on p-Si and quartz substrates by reactive magnetron sputtering and the influence of substrate bias voltage (V-b) on their structural and electrical properties was studied. The crystal structure of the prepared films was elucidated by X-ray diffraction (XRD) studies. The structure of the as deposited films was found to be amorphous and the surface roughness of the films was found to be low. The crystallinity of the films was observed to be improved by increasing the substrate bias voltage. The XPS results revealed that the composition of the films were nearly stoichiometric with V-b at 0 V and -150 V. The optical properties of the films at various substrate bias voltages were also studied. The optical band gap of the films formed at various V-b values from 0 to -150 V decreased from 4.49 to 4.39 eV as revealed from the optical transmission spectra. The fabricated Al/(Ta2O5)(0.85)(TiO2)(0.15)/p-Si metal-insulator-semiconductor (MIS) Schottky diodes leakage currents at -1.5 V decreased from 4.65 x 10(-6) A (unbiased) to 3.73 x 10(-8) A (V-b = -100 V). On the other hand, the sample biased at V-b = -150 V exhibited an increase in leakage current (2.99 x 10(-4) A) when compared to all other prepared samples. Furthermore, the electrical parameters such as Schottky barrier height and ideality factor were calculated for the Al/(Ta2O5)(0.85)(TiO2)(0.15)/p-Si MIS Schottky structure and systematically investigated as a function of substrate bias voltage using current-voltage (I-V) and capacitance- voltage (C-V) characteristics

Highly stable CsPbBr3/ PMA perovskite nanocrystals for improved optical performance

In this study, to address the stability issues, we synthesized a CsPbBr3-coated poly (maleic anhydride-alt-1-octadecene) (CsPbBr3/PMA) using a modified hot-injection method. The CsPbBr3/PMA perovskite nanocrystals (PNCs) exhibited effective green emission at 522 nm with an improved photoluminescence quantum yield (86.8 %) compared to traditional CsPbBr3 PNCs (54.2 %). The ligands in the polymer coating can bond with the uncoordinated Pb and Br ions on the surface of PNCs to minimize surface defects and avoid exposure to the external environment, enhancing the stability of the perovskites. Time-resolved photoluminescence spectra showed longer lifetimes for CsPbBr3/PMA PNCs, while transient absorption measurements provided valuable insights into the intraband hot-exciton relaxation and recombination. We demonstrate the potential application of CSPbBr3/PMA in a down-conversion white-light-emitting diode (LED) by coupling green CsPbBr3/PMA and red K2SiF6:Mn4+ phosphor-coated glass slides onto a 455-nm blue GaN LED. The white LED produced a white light with the International Commission on Illumination color coordinates of (0.323, 0.345), luminous efficiency of 58.4 lm/W, and color rendering index of 83.2. The fabricated, white-LED system obtained a wide color gamut of 125.3 % of the National Television Standards Committee and 98.9 % of Rec. 2020. The findings demonstrate that CsPbBr3/PMA can be an efficient down-conversion material for white LEDs and backlighting