Ionics最新文献

Nanocomposites of multi-wall carbon nanotubes (MWCNTs)/zinc oxide (ZnO) were produced successfully using the sol-gel method. The structural, morphological and chemical properties of the nanostructured ZnO is studied after composited with three different amounts of MWCNTs (1, 2, 5 wt%). X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDS), Brunauer Emmett Teller (BET) surface area analyzer and Raman scattering spectroscopy were employed for the characterization of the samples. The XRD analysis of all samples indicate the presence of a wurtzite hexagonal nanocrystalline structure of the ZnO compound, with no detection of any other phases. The FE-SEM images of nanocomposite samples show a porous structure with elongated MWCNTs. The size of ZnO nanoparticles, as measured from the FE-SEM images, shows a progressive reduction, 29.75, 28.60, 24.74, and 22.59 nm for pure ZnO, 1, 2, and 5 wt% MWCNT, respectively. The EDS analysis confirm the presence of Zn, O, and C, consistent with the XRD results indicating the formation of ZnO nanoparticles. The presence of MWCNTs in the ZnO/MWCNT nanocomposite was confirmed by Raman spectroscopy, which showed characteristic D and G bands at 1357 and 1588 cm⁻¹, respectively. Based on the BET analysis, the specific surface areas increase due to presence of MWCNTs in the structure. The specific surface areas of the samples are 15, 19, 17, and 29 m²/g for pure ZnO, 1, 2, and 5 wt% MWCNT, respectively. The ZnO/5%MWCNT nanocomposite demonstrate a twofold increase in photocurrent density (3.75 µA.cm^− 2) compared to the bare ZnO photoelectrode, along with enhanced optical and electrochemical properties. These results suggest the great potential of ZnO/MWCNT nanocomposites for photocatalytic applications and energy conversion.

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This study uses the sol-gel technique for the synthesis of the lithium compounds LiMPO₄, where M = Ag, Cu, and Al, as a cathode for the aqueous rechargeable Li-ion battery. A heat treatment at 700 °C was applied to the samples for one hour. LiAgPO₄, LiCuPO₄ and LiAlPO₄ had average crystalline sizes of 13.44 nm, 14.96 nm and 17.06 nm, respectively, using Debye-Scherrer. Utilising X-ray diffraction (XRD), the structural properties of these samples were investigated. VSM was employed to determine the magnetic properties of the samples. The results showed that the olivine materials (LiAgPO₄ and LiAlPO₄) were formed in an orthorhombic structure crystalline shape, while LiCuPO₄ was formed in a cubic shape. It has been demonstrated in field emission microscopic images that olivine cathode nanoparticles agglomerate because of their magnetic properties and the binding of parent particles held by surface interaction. The cyclic voltammogram of LiAgPO₄ exhibits a characteristic redox reaction peak at around 0.61 V against Li/Li⁺ and LiCuPO4 at ~ 0.96 V vs. Li/Li⁺, while LiAlPO₄ is at ~ 0.99 V vs. Li/Li⁺ but weakly. The improved electrochemical performance increases primarily as the grain size decreases.

NiO/g-C₃N₄ nanocomposites have been produced in this study using a co-precipitation technique. Throughout this study, NiO/g-C₃N₄ NCs have been designated to act as an endpoint agent to develop the particles and carry out the processes of decreasing toxicity, enhancing stability, and inhibiting agglutination, respectively. FTIR, XRD, UV-DRS, SEM/EDX, BET, and HR-TEM analyses have been used to assess the phase studies, morphology, and structure of NiO/g-C₃N₄ NCs. Furthermore, NiO/g-C₃N₄ NCs photocatalytic effects on the degradation of methyl orange (MO) have been studied, and the results show that they have a lot of promise as UV photocatalysts. A cubic structure with an average crystallite size of 18 nm is shown by XRD. At 470 cm^− 1, the nickel-oxygen bond’s vibrational stretching mode is detected. It is discovered that the optical energy bandgap value of NiO/g-C₃N₄ NCs is 2.38 eV. When NiO is coupled with n-type g-C₃N₄, a p–n heterojunction is formed at the interface. This heterojunction facilitates efficient charge separation and suppresses electron–hole recombination, which significantly enhances photocatalytic performance under visible-light irradiation. To overcome these drawbacks, coupling g-C₃N₄ with suitable semiconductors such as NiO can effectively enhance light absorption, promote charge separation, and improve overall photocatalytic performance. With an outstanding degradation efficiency of 90.36%, NiO/g-C₃N₄ NCs demonstrated the greatest photocatalytic degradation performance for MO dye. Applications for high-performance photocatalysis may employ these NCs materials. The fabrication of NiO/g-C₃N₄ nanocomposites is driven by the need to enhance the photocatalytic efficiency of g-C₃N₄, which, despite being a promising visible-light photocatalyst, suffers from low surface area, limited visible-light absorption, and rapid recombination of photogenerated charge carriers. Graphitic carbon nitride (g-C₃N₄) is an attractive, metal-free semiconductor with a moderate band gap (~ 2.7 eV), high stability, and eco-friendly characteristics; however, its practical application in photocatalysis remains limited due to poor charge separation and transfer efficiency.

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The development of anodes with high discharge capacity and excellent rate capability has attracted increasing attention. In this work, SnO₂ nanoparticles embedded within chlorine-doped graphene (SnO₂/Cl-rGO) were synthesized using a facile heat treatment method. Chlorine doping enhances the wettability of electrolyte to SnO₂/Cl-rGO surface, thereby increasing the lithium-ion diffusion rate. Meanwhile, the doped chlorine atoms form strong interactions with lithium ions, leading to an increase in lithium storage sites. As a result, the SnO₂/Cl-rGO exhibits a high discharge capacity of 610 mAh g^–1 after 300 cycles at a current density of 0.2 A g^–1. Following rate capability testing, the SnO₂/Cl-rGO was cycled for another 200 cycles, and a discharge capacity of 603 mAh g^–1 was retained, further demonstrating its potential as a high-performance anode material for lithium-ion batteries. This work on chlorine-doped graphene embedding SnO₂ provides valuable insights for the preparation of next-generation high-performance anode materials.

Nickel oxide (NiO)-based materials have emerged as promising anode candidates for lithium-ion batteries due to their high theoretical capacity (718 mA h/g) and cost-effectiveness. However, their practical application is hindered by substantial volume expansion during cycling and intrinsically poor electrical conductivity, while their conventional fabrication often relies on environmentally harmful solvents. To address these dual challenges, we report the hierarchically structured NiO nanoparticle-assembled nanofibers (NiO@NFs) through a green electrospinning approach using environmentally benign ethanol as the sole solvent, which serves as a safe and sustainable alternative to the commonly used toxic solvents combined with an in-situ oxidation strategy. Owing to the unique 0D/1D nanoparticle-nanofiber structure, the optimized NiO@NFs electrode exhibited a high lithium storage capacity, excellent rate capability, and outstanding cycling stability, including a high initial capacity of 857 mA h/g at 0.1 A/g, and remarkable cycling stability (519 mA h/g after 200 cycles). This ethanol-based green fabrication process not only eliminates the need for toxic solvents but also enables precise control over material composition and morphology. This work presents a generalizable strategy for developing high-performance metal oxide-based electrodes, offering new opportunities for advanced energy storage systems. 

Aluminium (Al)-substituted BiFeO3 (Bi_1-xAl_xFeO₃) nanoparticles were synthesised via a solution-combustion route using L-alanine as fuel, and their structural, optical, magnetic, and electrochemical properties were systematically investigated. X-ray diffraction confirmed a rhombohedral perovskite structure, while TEM/EDX analyses verified uniform Al incorporation within nanoparticles averaging 38–55 nm in size. Diffuse reflectance spectroscopy revealed a reduction in the band gap from 2.16 eV (undoped) to 2.12 eV with 10% Al doping, indicating improved electronic conductivity. Electrochemical measurements in 3 M KOH demonstrated a specific capacitance of 224 F g^-1 at 10 mV s^-1, representing a ~ 26% enhancement over undoped BiFeO3, along with excellent rate capability and > 95% capacitance retention after 5000 cycles. Impedance spectra exhibit a depressed high-frequency arc and a low-frequency diffusion tail; fitting with Rs-(Rct ∥ CPE)-Zw yields reduced Rct for the Al-substituted samples relative to undoped BiFeO3, evidencing faster interfacial charge transfer. Vibrating sample magnetometry showed a doping-induced increase in the ferromagnetic component at room temperature, attributed to cation substitution and strain effects. The combined improvements in charge storage, magnetic response, and optical properties highlight Al-doped BiFeO₃ as a promising multifunctional material for energy storage and spintronic applications.

The pursuit of highly active, durable, and earth-abundant electrocatalysts for the oxygen evolution reaction (OER) is essential for the advancement of next-generation energy conversion technologies. However, achieving a balance between high catalytic activity, long-term stability, and the use of cost-effective, earth-abundant materials remains a significant challenge in the development of efficient OER electrocatalysts. The dual-phase systems exhibit remarkable electrochemical stability, a dramatically reduced charge transfer resistance, robustness and efficiency under long-term operating conditions. In this study, we report the fabrication of a novel dual-phase Ni₃B-CoS₂ electrocatalyst through a sequential approach involving chemical reduction followed by hydrothermal synthesis. This composite integrates the advantageous properties of transition metal borides and chalcogenides, creating a rich network of hetero interfaces that serve as highly active sites for OER. The OER activity of resulting Ni₃B-CoS₂ electrocatalyst demonstrates a low overpotential of 120 mV at a current density of 20 mA cm^-2 and Tafel slope of 214 mV dec^-1 in 1.0 M KOH. This dual Ni boride-Co sulfide system tailored specifically for OER, represent a significant advancement in the field of non-noble metal-based electrocatalysts, offering promising prospects for practical applications in sustainable energy technologies.

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Sodium-ion batteries are emerging as a next-generation battery technology, owing to their abundant raw material. The physics-based pseudo-2-dimensional model is widely used to understand their electrochemical behaviour; however, this model is computationally intensive. To address this issue, this study presents a reduced-order tanks-in-series model consisting of a system of differential-algebraic equations. This model offers computational efficiency while maintaining prediction accuracy, making it a potential candidate for battery management systems. The model variables are volume-averaged in a given domain and are solved at the interface regions in a cathode-separator-anode representation. The pseudo-2-dimensional model is set as a benchmark to evaluate the cell-level quantities. The battery electrodes in this study undergo phase changes and exhibit concentration-dependent diffusivity, which is modelled using the Galerkin formulation. The electrolyte potential variation is modelled with the incorporation of dilute solution theory. The simulation is conducted for various current densities and the electric vehicle drive cycle to evaluate constant current and dynamic operating conditions. The Root Mean Square Error is 3 mV at 1C and 13 mV at 1.5C discharge rate. The tanks-in-series model demonstrates considerable agreement at lower C-rates, with minor deviations at higher discharge rates, which are attributed to the overpotential and averaged molar flux.

An energy storage device is one of greatest promising alternative resources to address escalating energy crisis and contribute significantly to economic development in the modern world. Supercapacitors have drawn attention from scientists as a possible substitute for electrochemical energy storage gadgets in recent decades, mainly due to having exceptional efficiency and greatly increased cycle life. Herein, ZnMoO₄/PANI nanocomposites fabricated via hydrothermal route. Several characterizations techniques were utilized to study the physical properties of produced materials. Scanning electron microscope and Brunauer Emmett Teller have been used to examine morphology and surface area (SA) specifications of produced nanostructure. The composite material’s wider active regions, lower resistance, and enhanced SA (132 m² g^− 1) than ZnMoO₄ (78 m² g^− 1) are responsible for better electrochemical activity. A three-electrode arrangement was used for testing, the ZnMoO₄/PANI electrode demonstrated superior charge-storing capacity with a high specific capacitance (C_sp) of 1243.44 F g^− 1. Furthermore, the two-electrode asymmetric SC_s device demonstrated) high C_sp of 218 F g^− 1 at 1 A g^− 1 and outstanding energy density of 57.81 Wh kg^− 1 and power density 690.08 W kg^− 1. The ZnMoO_4, PANI, and ZnMoO₄/PANI nanocomposites have R_ct values of (0.103, 0.098, and 0.078) Ω, respectively. Although ZnMoO₄/PANI has a favourable SA, lower obstacles, and faster electrolytic ion transport than its constituent parts, it has excellent electrochemical characteristics. The ZnMoO₄/PANI nanocomposite demonstrated outstanding CV stability during the 10000^th cycle. The results demonstrated that using ZnMoO₄/PANI nanocomposite as energy storage electrode materials would be a desirable and economical strategy.

Sodium-ion batteries have garnered extensive attention as potential alternatives to lithium-ion batteries due to their advantages of abundant sodium resources and low production costs. However, the larger ionic radius of sodium restricts the charge storage capacity of electrode materials and hinders ion transport efficiency, resulting in inferior energy density and power characteristics that severely impede practical applications. This study investigates the influence mechanism of sodium content adjustment on the energy storage properties of layered oxides and employs MgO surface coating to enhance structural stability while suppressing interfacial side reactions. A series of Na_xMn_0.7Ni_0.2Co_0.1O₂ (x = 0.65, 0.70, 0.75, denoted as Na_xMNCO) samples were synthesized via a sol-gel method. Experimental results demonstrate optimal electrochemical performance at x = 0.70: the material exhibits a specific capacity of 156.75 mAh·g^− 1 during initial charge-discharge cycles within 2.0–4.2 V voltage window at 0.1 C rate (1 C = 200 mA·g^− 1). After 200 charge-discharge cycles, 84.6% of the initial capacity remains, indicating excellent cyclic stability. Building on these findings, liquid-phase chemical deposition was used to create adjustable MgO protective layers on the positive electrode material. Optimal electrochemical performance was achieved with 3 wt% MgO coating. The modified sample delivered an initial discharge specific capacity of 159.9 mAh·g^− 1 and maintained 89.4% capacity retention after 200 cycles, demonstrating significantly improved cyclic stability compared to unmodified materials. This systematic investigation of sodium content optimization and MgO coating engineering in layered Ni/Mn-based sodium-ion battery cathode materials may represent an important step toward the commercial viability of sodium-ion battery technology.