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.

This study investigates the effects of adding titanium dioxide (TiO₂) particles to the negative electrode of a vanadium redox flow battery (VRFB) on the battery's performance. Results show that TiO₂ addition changes the wettability and electrical resistance of the electrode surface. The water contact angle on the electrode surface decreases with increased weight percentage of TiO₂ particles in the electrode. The electrochemical performance of these electrodes with different loading amounts is studied by cyclic voltammetry and single-cell charge–discharge measurements. Adding an adequate amount of TiO₂ particles to the carbon electrode promotes the electrode specific capacitance and charge–discharge efficiency of a single cell. An electrode with 20 wt% TiO₂ loading at a scan rate of 0.04 V s⁻¹ shows a high specific capacitance (C_s,t) of 156.2 F g⁻¹, which is 59.1% higher than that of pure carbon electrode (98.2 F g⁻¹). Similarly, the energy storage efficiency (η_E = 72.5%) of a single TiO₂/C cell with 20 wt% modified carbon felt is 30.4% higher than that of a cell with raw carbon felt (η_E = 55.6%). Thus, the TiO₂/C electrode increases the cell energy storage efficiency. These results demonstrate the potential application of TiO₂/C electrode in VRFBs.

The electronic and optical properties of polythiophene (PT) for polymer light-emitting diodes (PLEDs) were calculated using density functional theory (DFT) and time-dependent DFT. We calculated the electronic and optical properties of thiophene and PT polymers with degrees of polymerization (DP) from 2 to 30 monomers (T1–T30) and their derivatives. The associated highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, band gaps, electron orbitals, and molecular structures were determined. As the DP increased, the LUMO energy gradually decreased, and the HOMO energy gradually increased. The band gap of PT approached 2 eV as the DP of the PT polymer increased from 1 to 30. The calculations and exchange–correlation functional were verified against values in the literature and experimental data from cyclic voltammetry (redox potential) and ultraviolet-visible, photoluminescence, and ultraviolet photoelectron spectra. The color of PT PLEDs can be adjusted by controlling the DP of the polymer and the substituents.

Zn-air batteries have attracted considerable attention from researchers owing to their high theoretical energy density and the abundance of zinc on Earth. The modification of battery component materials represent a common approach to improve battery performance. The effects of cell design on cell performance are seldom investigated. In this study, we designed four battery structures as follows. Cell 1: close-proximity electrode, Cell 2: equal-area electrode, Cell 3: large zinc electrode, and Cell 4: air channel flow. The effects of four factors: (1) carbon paste, (2) natural and forced air convection, (3) anode/cathode area ratio, and (4) anode–cathode distance were also investigated. Results showed that the addition of carbon paste on the air side of 25BC increased cell power density under forced air convection. Moreover, cell performance also improved by increasing the anode/cathode ratio and by decreasing the anode–cathode distance. These four types of cells were compared based on the oxygen reduction reaction electrode area. Cell 3 displayed the highest power density. In terms of volumetric power density, the proximity cell (Cell 1) exhibited the highest power density among the cells. Therefore, this cell configuration may be suitable for portable applications.

Metal–air batteries exhibit high potential for grid-scale energy storage because of their high theoretical energy density, their abundance in the earth’s crust, and their low cost. In these batteries, the oxygen evolution reaction (OER) occurs on the air electrode during charging. This study proposes a method for improving the OER electrode performance. The method involves sequentially depositing a Ni underlayer, Sn whiskers, and a Ni protection layer on the metal mesh. Small and uniform gas bubbles form on the Ni/Sn/Ni mesh, leading to low overpotential and a decrease in the overall resistance of the OER electrode. The results of a simulated life cycle test indicate that the Ni/Sn/Ni mesh has a life cycle longer than 1,300 cycles when it is used as the OER electrode in 6 M KOH.