Modifying pristine graphite felt (GF) active electrode, highly active platinum/multiwalled carbon nanotubes (Pt/MWNTs) electrocatalyst, helps in developing new V(III)/V(V) vanadium redox flow battery (VRFB) and the improving the performance of the V(II)/V(V) battery. Cyclic voltammetry analyzes demonstrated that Pt/MWNT electrocatalyst has an excellent capacity for enhancing V³⁺/VO²⁺ and VO²⁺/VO₂⁺ redox reactions, and both reactions are quasireversible. The V³⁺/VO²⁺ redox couple provides the V(III)/V(V) battery redox reaction. The VO²⁺/VO₂⁺ and V³⁺/VO²⁺ redox reactions occurred in the pristine GF of the positive active electrode and in the Pt/MWNT + GF of the negative active electrode, respectively, using the same electrolyte (1 M VO²⁺ –1 M H₂SO₄). At the operating current densities of 12 and 20 mA cm⁻², the cell coulombic efficiency reached 93.75% and 83.88%, respectively. A test V(II)/V(V) battery was assembled with the positive active electrode of Pt/MWNT + GF and the negative active electrode of the GF. The charge–discharge curves showed a slight IR drop in the active electrode, which was likely caused by the Pt/MWNT electrocatalyst. At an operating current density of 20 mA cm⁻², the cell energy efficiency was 11.58% higher than that without an electrocatalyst. The results show the potential of Pt/MWNT catalysts in VRFB applications.

In this study, we use nitrogen-doped to improving the gas-sensing properties of reduced graphene oxide. Graphene oxide was prepared according to a modified Hummers’ method and then nitrogen-doped reduced graphene oxide (N-rGO) was synthesized by a hydrothermal method using graphene oxide and NH₄OH as precursors. The rGO is flat and smooth with a sheet-like morphology while the N-rGO exhibits folded morphology. This type of folding of the surface morphology can increase the gas sensitivity. The N-rGO and the rGO sensors showed n-type and p-type semiconducting behaviors in ambient conditions, respectively, and were responsive to low concentrations of NO gases (< 1000 ppb) at room temperature. The gas-sensing results showed that the N-rGO sensors could detect NO gas at concentrations as low as 400 ppb. The sensitivity of the N-rGO sensor to 1000 ppb NO (1.7) is much better than that of the rGO sensor (0.012). Compared with pure rGO, N-rGO exhibited a higher sensitivity and excellent reproducibility.

Al-free and Al-doped V₂O₅ nanostructures were synthesized by a thermal-chemical vapor deposition (CVD) process on Si(100) at 850 °C under 1.2 × 10⁻¹ Torr via a vapor-solid (V-S) mechanism. X-ray diffraction (XRD), Raman, and high-resolution transmission electron microscopy (HRTEM) confirmed a typical orthorhombic V₂O₅ with the growth direction along [110]-direction of both nanostructures. Metallic Al, rather than Al³⁺-ion, was detected by X-ray photoelectron spectroscopy (XPS), affected the V₂O₅ crystallinity. The photoluminescence intensity of V₂O₅ nanostructure at 1.77 and 1.94 eV decreased with the increasing Al-dopant by about 61.6% and 59.9%, attributing to the metallic Al intercalated between the V₂O₅-layers and/or filled in the oxygen vacancies, which behaved as electron sinks. Thus the Al-doped V₂O₅ nanostructure shows the potential applications in smart windows and the electrodic material in a Li-ion battery.

In this study, TiVCr and TiVCrZrY films were deposited on Si substrates by magnetron sputtering with the application of radio-frequency substrate bias of different powers from 0 to 15 W. The crystal structures, microstructure, and mechanical, electrical, and optical properties under the effect of bias were characterized. Both the TiVCr and TiVCrZrY films constructed simple solid solutions from all alloyed elements. The TiVCr films possessed a body-centered cubic crystal structure with a pyramid-like surface, while the TiVCrZrY films had a hexagonal close-packed crystal structure with a domelike surface. The microstructure and properties of the films varied with bias power. As the bias power increased, the microstructure of the films obviously changed from a porous to a dense columnar feature, and the density of the voids existing between the columns decreased. Accordingly, the physical properties of the films were improved. The hardness of the TiVCr and TiVCrZrY films was enhanced to about 11 and 14 GPa, and the electrical resistivity was lowered to 80 and , respectively.

This letter reports a technique for increasing the carrier concentration and the conductivity of the p-type CuAlO2 through doping the material with nitrogen. The x-ray photoelectron spectroscopy and the optical band gap analyses suggested that the nitrogen atoms occupying the interstitial sites of the delafossite structure provided the p-type CuAlO2 with an impurity energy level in the energy gap. It was also found that the N-doped CuAlO2 film had its optimum conduction properties when the dopant level reached 1.1at.%. Here, the carrier concentration was raised from 4.81×1016 in the undoped film to 2.13×1017cm−3 in the doped film, and the corresponding film’s conductivity was increased from 3.8×10−2to5.4×10−2(Ωcm)−1, as compared with the undoped CuAlO2 film.

An experimental investigation is performed into the thermal decomposition of Ni₃C nanoparticles (NPs) under an inert nitrogen atmosphere at temperatures ranging from 300 to 800 °C. It is shown that given a decomposition temperature of 500 °C, a hexagonal close-packed (HCP) Ni phase is formed with cell constants of a = 0.2496 nm and c = 0.4078 nm. These constants are similar to those predicted theoretically for interstitial-atom-free (IAF) HCP Ni. Thus, it is inferred that the HCP Ni phase is formed as an intermediate phase during the thermal decomposition of Ni₃C into face-centered cubic (FCC) Ni and carbon. The transmission electron microscopy (TEM) results suggest that the formation of this IAF HCP Ni phase is due to the adhesion of a graphite-like shell on the Ni NPs, which constrains the slip of the close-packed layers and therefore hinders the HCP Ni to FCC Ni transformation process. The magnetization results show that the saturation magnetization (M_s) increases with increasing HCP Ni content. In addition, the extrapolation results suggest that the M_s value of the IAF HCP Ni phase is equal to 70.1 emu g⁻¹ at a temperature of 300 K. In other words, the IAF HCP Ni phase is ferromagnetic with a magnetic moment slightly higher than that of FCC Ni. Overall, the results presented in this study provide a useful insight into the magnetization properties of the HCP Ni phase and are consistent with the theoretical predictions.