Ionics最新文献

This study analyzes new artificial changes in innovative gas diffusion layers (GDLs) to maximize the performance of proton exchange membrane fuel cells (PEMFCs). Specifically, a new perforated grooved uniform gas diffusion layer (PG-GDL) is used to improve the water drainage and oxygen transport using three-dimensional modeling and simulations of a single-channel PEMFC. Comparative analyses are performed between the different perforated GDLs and the conventional GDLs using groove depth inside a PG-GDL. Findings show that the uniform grooved shape in the PG-GDL produces a more uniform oxygen flow and distribution with an overall improvement in the PEMFC performance. Our study shows that the appropriate GDL design should be obtained to optimize the PEMFC performance.

Solid polymer electrolytes (SPEs) show great promise for high-energy and high-safety lithium metal batteries. However, current SPEs suffer from low ionic conductivity and poor mechanical strength. Herein, the g-C₃N₄@COF heterojunction filler is constructed for SPEs for fast Li⁺ transport and high Li⁺ transference number. In addition, a robust 3D network is fabricated by using g-C₃N₄@COF heterojunction filler in order to further improve the mechanical robustness and electrochemical stability. As a consequence, the g-C₃N₄@COF-3D network/polymer electrolyte displays an ionic conductivity of 1.25×10⁻⁴ S cm⁻¹ at 30 ℃, an electrochemical window of 5.0 V and the tensile strength of 8.613 MPa. Furthermore, the assembled LiFePO₄//Li battery with the g-C₃N₄@COF-3D network/polymer electrolyte presents remarkable cycling stability with a capacity retention of 99.71% after 600 cycles. The above results indicate the great potential of the g-C₃N₄@COF-3D network/polymer electrolyte for advanced energy storage devices.

In this paper, based on the principle of gradient aperture, a cathode gas diffusion layer with three microporous layers was prepared using conductive carbon black with three different particle sizes. The thickness of the microporous layers was studied, and a gradient hydrophobic structure was designed. The purpose was to maximize the output performance of the cell by adjusting the preparation parameters of the microporous layers. The physical and electrochemical properties of each sample showed that the change in micropore layer thickness redistributed the pore size distribution of the gas diffusion layer, especially increasing the number of pore sizes in the range of 20–40 µm. They improved the liquid water transport capacity of the gas diffusion layer at high current density. The gradient hydrophobic structure of the microporous layer promoted the cathode gas diffusion layer to expel liquid water in time and ensure the oxygen supply. The results showed that when the microporous layer thickness was 60 µm. The hydrophobic agent content in the three microporous layers was 10 wt%, 20 wt%, and 30 wt%, respectively, the limiting power densities of 0.883, 0.916, and 0.863 W/cm² could be achieved under the three humidity conditions of 40%, 60%, and 100%, respectively. The limiting power density increased by 17.1%, 12.0%, and 18.1%, respectively, compared with the samples with the same optimal thickness but no gradient hydrophobic structure.

Cuprous oxide (Cu₂O) is a highly promising photocatalyst that facilitates efficient water splitting and hydrogen production under light conditions. In this study, Cu₂O thin film photocathodes were prepared through electro-deposition, with the inclusion of (mathrm{NO}^{-}_{3}) ions resulting in the formation of a flower-like microstructure. The size, distribution and roughness of these clusters were found to be greatly influenced by the concentration of the (mathrm{NO}^{-}_{3})  ions as confirmed by SEM and AFM characterizations. When 0.4 M (mathrm{NO}^{-}_{3}) ions were used, a flat and compact structure with the smallest ‘flower bud’ was obtained. This structure achieved a maximum photocurrent density of − 2.90 mA/cm² @0 V vs. RHE, which is 2.2 times greater than that of bare Cu₂O. UV–Vis absorption, steady-state fluorescence spectroscopy and EIS measurements suggest that the compact microstructure facilitates enhanced ultraviolet absorption and separation of photogenerated holes and electrons. This results in a lower charge transfer resistance and a significant increase in photocurrent density. Additionally, a growth mechanism for the flower-like Cu₂O was proposed. The XPS and EDS analyses indicate that the addition of (mathrm{NO}^{-}_{3}) during Cu₂O formation results in the adsorption of (mathrm{NO}^{-}_{3}) onto the surface of the initial Cu₂O grain. This, in turn, catalyses the electrocatalytic reduction of (mathrm{NO}^{-}_{3}) on the surface of Cu₂O, leading to the formation of NH + 4 ions as evidenced by XPS.

This study introduces a novel hybrid nanomaterial, C₃N₄-PTh-PEDOT, synthesized through a chemical oxidative technique. The research addresses the need for materials with enhanced catalytic properties and stability for diverse applications. The C₃N₄-PTh-PEDOT material exhibits significant improvements in catalytic performance, suitable for applications such as organic binder-free sources, modifications of glassy carbon electrode (GCE) electrodes, and as a reducing agent-free photocatalyst. The material demonstrates rapid electron transfer and excellent electrochemical stability, thanks to its core–shell structures and the interaction between the conjugated polymers PTh and PEDOT with C₃N₄. This hybrid material achieves 97.47% degradation of methyl blue (MB) in 80 min by minimizing electron–hole recombination, enhancing photocatalytic activity. Additionally, the C₃N₄-PTh-PEDOT-modified GCE enables sensitive detection of oxyfendazole (OFZ) using differential pulse voltammetry, showing a linear response within the concentration range of 0.32 × 10⁻⁷ to 3.7 × 10⁻⁸ M, with a sensitivity of 3.156 × 10⁻⁸ M µA⁻¹ and a limit of quantification of 10.7787 × 10⁻⁸ M µA⁻¹.

Graphical Abstract

Mg⁺-ion-conducting tamarind gum (TG)-based biopolymer electrolytes (BPEs) are prepared by a simple solution-casting technique. XRD and FTIR analyses have revealed the dissociation and complexation of the salt with the polymer host. The glass transition temperature is observed for all the prepared electrolytes using differential scanning calorimetry (DSC). By using AC impedance analysis, the higher ionic conductivity calculated for the sample 1-g TG with 0.5 g of salt (5 TML) is 3.48 × 10⁻³ S/cm. The temperature-dependent conduction mechanism of sample 5 TML follows three models: region I obeys the overlapping-large polaron tunneling (OLPT) model, the quantum mechanical tunneling (QMT) model is observed in region II, and region III obeys the nonoverlapping small polaron tunneling (NSPT) model. The minimum activation energy of 0.045 eV is observed for sample 5 TML according to the Arrhenius plot. The complex dielectric permittivity and dielectric modulus spectra are discussed. The relaxation time (τ) attained by tangent analysis for 5 TML is 7.94 × 10⁻⁷ s. From the transference number measurement, it is concluded that the conductivity is mostly due to the transfer of ions only. Using the 5 TML sample, a symmetrical supercapacitor and an electrochemical cell are fabricated. Cyclic voltammetry (CV) reveals a specific capacitance of 413.05 Fg⁻¹ at a low scan rate of 15 mV/s. From the GCD data, the power and energy density are calculated as 1499 W/kg and 100 Wh/kg, respectively. The cyclic stability is confirmed by the observed constant values of power and energy densities for different cycles.

A new PPy/PANI/MnO₂ polymer nanocomposite was synthesized through chemical oxidative polymerization process and fabricated as an efficient ternary electrode material for supercapacitors. All the synthesized nanomaterials were characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM/EDAX), High-resolution transmission electron microscopy (HR-TEM), Brunner-Emmett-Teller theory (BET), and X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical behavior of ternary PPy/PANI/MnO₂ electrode was initially tested in neutral (1 M Na₂SO₄), alkaline (1 M KOH) and acidic (1 M H₂SO₄) electrolytes through cyclic voltammetry (CV) at a scan rate of 5 mV/s to fix the electrolyte. PPy/PANI/MnO₂electrode exhibited the maximum specific capacitance of 303.92 Fg⁻¹ in 1 M Na₂SO₄ electrolyte than in alkaline (82.93 Fg⁻¹) and acidic (136.64 Fg⁻¹) electrolytes. From GCD studies, PPy/PANI/MnO₂ exhibited a maximum specific capacitance of 309.61 Fg⁻¹ at a current density of 5 A/g with 84% capacitive retention after 2500 charge/discharge cycles. Further, symmetric supercapacitor fabricated using PPy/PANI/MnO₂ electrodes exhibited a specific capacitance of 181.5 Fg⁻¹, energy density of 36.31 Wh/kg and power density of 2000 W/kg at 5 A/g. The low ESR (1.12 Ω) value exhibited by the fabricated supercapacitor and its capacitive retentivity of 79% at the end of 3000 charge/discharge cycles demonstrate its suitability for energy storage applications.