Search Results (335)

Precise control over nanostructure evolution is critical for optimizing the electrochemical performance of pseudocapacitive materials. In this work, Nb₂O₅ nanostructures were synthesized via a time-engineered hydrothermal route by systematically varying the reaction duration (6, 12, and 18 h) to elucidate its influence on structural development, charge storage kinetics, and supercapacitor performance. Structural and surface analyses confirm the formation of phase-pure monoclinic Nb₂O₅ with a stable Nb⁵⁺ oxidation state. Morphological investigations reveal that a 12 h reaction time produces hierarchically organized Nb₂O₅ architectures composed of nanograin-assembled spherical aggregates with interconnected porosity, providing optimized ion diffusion pathways and enhanced electroactive surface exposure. Electrochemical evaluation demonstrates that the NbO-12 electrode delivers superior pseudocapacitive behavior dominated by diffusion-controlled Nb⁵⁺/Nb⁴⁺ redox reactions, exhibiting high areal capacitance (5.504 F cm⁻² at 8 mA cm⁻²), fast ion diffusion kinetics, low internal resistance, and excellent cycling stability with 85.73% capacitance retention over 12,000 cycles. Furthermore, an asymmetric pouch-type supercapacitor assembled using NbO-12 as the positive electrode and activated carbon as the negative electrode operates stably over a wide voltage window of 1.5 V, delivering an energy density of 0.101 mWh cm⁻² with outstanding durability. This study establishes hydrothermal reaction-time engineering as an effective strategy for tailoring Nb₂O₅ nanostructures and provides valuable insights for the rational design of high-performance pseudocapacitive electrodes for advanced energy storage systems. Full article

Supercapacitors have attracted significant interest as increased energy storage devices due to their high power density, rapid charge/discharge performance, and long cyclability. In this study, NiO, Co₃O₄, NCO, and NCO/rGO composite electrodes were prepared and evaluated for high-performance supercapacitor applications. The uniform distribution of elements and the effective incorporation of rGO into the composite were confirmed by structural and morphological characterizations. Among the evaluated materials, the NCO/rGO electrode exhibited high electrochemical performance, delivering a specific capacitance of 998 F g⁻¹ in a three-electrode configuration, attributed to the enhanced redox activity of NiCo₂O₄ coupled with the enhanced electrical conductivity of rGO. Additionally, an asymmetric supercapacitor device with activated carbon as the negative electrode and NCO/rGO as the positive electrode showed a power density of 750 W kg⁻¹, an energy density of 29.2 Wh kg⁻¹, and a specific capacitance of 93.7 F g⁻¹. After 5000 charge/discharge cycles, the device maintained 85% of its initial capacitance and a coulombic efficiency of 99%, demonstrating exceptional cyclability. These results highlight the strong potential of the NiCo₂O₄/rGO composite as an advanced electrode material for next-generation energy storage systems. Full article

It is understood that 4-nitrophenol (4-NP) and its derivatives/isomers, such as m-NP and o-NP, are considered toxic nitroaromatic pollutants that pose health risks for human beings and have negative impacts on the environment. Therefore, monitoring of 4-NP is of particular importance to avoid the negative impacts of these environmental pollutants on aquatic life and human health. Electrochemical sensors have emerged as the most promising next-generation technology for the detection of environmental pollutants. The electrochemical method has been extensively used for the detection of 4-NP, p-NP, etc., which has delivered an interesting electrochemical performance. This review provides an overview of the advances in electrode modifiers designed for the electrochemical detection of 4-NP and its isomers. This review includes the use of carbon-based materials, metal oxides, metal sulfides, metal-organic-frameworks (MOFs), conducting polymers, MXenes, covalent organic frameworks (COF), and composites for the development of 4-NP electrochemical sensors. Various electrochemical techniques, such as differential pulse voltammetry, square wave voltammetry, linear sweep voltammetry, cyclic voltammetry (CV), electrochemical impedance spectroscopy, and amperometry, are discussed for the detection of 4-NP and other isomers. Full article

In this study, we investigated the electrochemical reduction of carbon dioxide (CO₂) using a phosphorus-doped polycrystalline diamond (PDD) electrode and compared it with a conventional boron-doped diamond (BDD) electrode. In the reduction reaction of CO₂ in a 0.5 M KCl aqueous solution, the PDD electrode showed high selectivity for formic acid production over a wide potential range. This tendency was particularly evident at potentials below −1.8 V (vs. RHE). Moreover, at more negative potentials of −2.4 V and −2.6 V, formic acid remained the dominant product, while hydrogen evolution was the main reaction on the BDD electrode at the negative potentials. Similarly, in electrochemical reduction using an 0.1 M KClO₄ aqueous solution, carbon monoxide was confirmed to be a major product, and hydrogen generation was effectively suppressed in a more negative potential range. In other words, PDD is a promising electrode material that can efficiently convert CO₂ into valuable chemicals while suppressing hydrogen evolution, even in negative potential regions. Full article

Currently, lithium-ion battery packaging has poor sealing and positive and negative electrodes are easily damaged by humid environments; therefore, we design a structure in which the inner packaging uses HL-1029 silicone gel to wrap the lithium-ion battery, and the outer packaging is packed in a corrugated carton. According to the lithium-ion battery model and size, the thickness of HL-1029 inclusions was calculated, the packaging model was established, and the stress contour plot diagram of HL-1029 inclusions and lithium-ion batteries under the 1200 mm drop height and two drop postures in the finite element environment was analyzed; the maximum stress of the lithium-ion battery did not exceed the yield strength of its material. Based on the energy method, the reliability analysis of the final finite element simulation results is carried out. When the two drop postures are 1200 mm in height, the maximum stresses of the lithium-ion batteries are 4.367 MPa and 4.555 MPa, respectively, and the ratios of the hourglass of energy to the internal energy of the packaging system are 0.700% and 1.190%, respectively. Based on the finite element analysis results and reliability verification, HL-1029 inclusions can provide sufficient protection during lithium-ion battery transportation and have high recyclability. Full article

Sodium-ion batteries have emerged as a promising alternative to lithium-ion systems, due to the abundance and low cost of sodium resources. However, the demand for higher performance is always increasing, and developing new electrode materials and optimizing their behavior in full cells is necessary. Their electrochemical performance remains limited by challenges related to the anode materials. A fundamental understanding of electrode materials is essential to advance their practical application, for example, by designing strategies to minimize irreversible processes and enhance the reversible capacity. Thus, the properties of metals, including nanoparticles and clusters, are critical for various types of sodium batteries, such as sodium-ion microbatteries. Additionally, metallic nanoparticles exhibiting special properties are generated in situ at the negative electrode during the electrochemical cycling of certain batteries. This review focuses on their formation mechanisms, structural and electrochemical effects, and strategies to control their distribution and size. Particular attention is given to the interaction between metallic particles and carbon matrices, as well as their influence on capacity. Finally, current limitations and future perspectives for optimizing the properties of the metallic particles in advanced sodium battery anodes are highlighted. Full article

It is well known that nitrite is widely used in industrial and agricultural sectors as a preservative, corrosion inhibitor, and intermediate in chemical synthesis; consequently, nitrite residues are often present in food, water, and the environment as a result of meat curing, fertilizer use, and wastewater discharge. Despite having several applications, nitrite exerts toxic effects on human beings and aquatic life. Therefore, the monitoring of nitrite is of particular significance to avoid negative impacts on human health, the environment, and aquatic life. Previously, the electrochemical method has been extensively used for the development of nitrite sensors using various advanced electrode materials. Additionally, zinc oxide (ZnO), cerium oxide (CeO₂), titanium dioxide (TiO₂), copper oxide (CuO), iron oxides, nickel oxide (NiO), polymers, MXenes, reduced graphene oxide (rGO), carbon nanotubes (CNTs), graphitic carbon nitride (gCN), metal–organic frameworks (MOFs), and other composites have been utilized as electrocatalysts for the fabrication of nitrite electrochemical sensors. This review article provides an overview of the construction of nitrite sensors using advanced electrode materials. The electrochemical activities of the reported nitrite sensors are discussed. Furthermore, limitations and future perspectives regarding the determination of nitrite are discussed. Full article

Phenolic compounds such as resorcinol (RS) have negative impacts on aquatic life, the environment, and human health. Thus, it is necessary to develop sensing devices for the monitoring of RS. The electrochemical method is one of the most significant approaches for the determination of toxic substances. In electrochemical methods, electrode modifiers play a vital role and affect the sensing performance of the electrochemical sensors. Thus, the selection of efficient electrode material is of great importance. In recent years, various electrode modifiers such as graphene, metal–organic frameworks (MOFs), MXenes, metal oxides, polymers, and composite materials have been extensively used for the fabrication of RS sensors. In this review, we have summarized the reported electrode modifiers for the fabrication of RS electrochemical sensors. Various electrochemical sensing techniques, including differential pulse voltammetry (DPV), square wave voltammetry (SWV), amperometry (Amp), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) have been discussed. This review provides an overview of a large number of electrode modifiers for the determination of RS. The limitations, challenges, and future perspectives for RS sensors are discussed. We believe that the present review article is beneficial for the scientific community and electrochemists working on the construction of RS sensors. Full article

The rational design of transition metal oxides with tailored electronic structures and defect chemistries is critical for advancing high-performance supercapacitors. Herein, we report the engineering of cobalt oxide (Co₃O₄) gels through controlled sol–gel synthesis and rare earth (RE) incorporation using neodymium (Nd), gadolinium (Gd), and dual neodymium/gadolinium (Nd/Gd) doping. X-ray diffraction (XRD) confirmed the preservation of the cubic spinel structure with systematic peak shifts and broadening, evidencing lattice strain, oxygen vacancy generation, and defect enrichment. Field-emission scanning electron microscopy (FE-SEM) analyses revealed distinct morphological evolution from compact nanoparticle assemblies in pristine Co₃O₄ to highly porous, interconnected frameworks in Nd/Gd–Co₃O₄ (Nd/Gd-Co). X-ray photoelectron spectroscopy (XPS) verified the stable incorporation of RE ions, accompanied by electronic interaction with the Co–O matrix and enhanced oxygen defect states. Electrochemical measurements demonstrated that the Nd/Gd–Co electrode achieved a remarkable areal capacitance of 25 F/cm² at 8 mA/cm², superior ionic diffusion coefficients, and the lowest equivalent series resistance (0.26 Ω) among all samples. Long-term cycling confirmed 84.35% capacitance retention with 94.46% coulombic efficiency after 12,000 cycles. Furthermore, the asymmetric pouch-type supercapacitor (APSD) constructed with Nd/Gd–Co as the positive electrode and activated carbon as the negative electrode delivered a wide operational window of 1.5 V, an areal capacitance of 140 mF/cm², an energy density of 0.044 mWh/cm², and 89.44% retention after 7000 cycles. These findings establish Nd/Gd-Co gels as robust and scalable electrode materials and demonstrate that RE co-doping is an effective strategy for bridging high energy density with long-term electrochemical stability in asymmetric supercapacitors. Full article

As a conceptual study for low-energy hydrogen production, potentially coupled with off-grid photovoltaics, this work focuses on overcoming the constraint of the oxygen evolution reaction (OER), which features a high anode potential and significant overpotential. To reduce energy consumption, the Fe²⁺ oxidation reaction is employed to replace OER, coupled with Fe²⁺ regeneration using natural biomass. Experimental results reveal that Fe²⁺ oxidation reaction is an effective substitute, with an initial oxidation potential of 0.5 V (vs. Hg/Hg₂SO₄), much lower than that of OER. Fe²⁺ regeneration is notably influenced by both biomass type and reaction temperature. Chlorella pyrenoidosa (CP) achieves the highest Fe³⁺ reduction rate of 90.5% at 190 °C. Water-soluble organic compounds generated during biomass oxidation exert a negative impact on Fe²⁺ electrooxidation by accumulating on or coating the electrode surface, and the compounds derived from CP exert a less detrimental effect. Moreover, enhancing magnetic stirring, elevating temperature, and selecting an appropriate anode material can significantly boost the oxidation reaction. Under optimized conditions, the current density during electrolysis of CP filtrate at 1.1 V reaches 280 mA/cm², much higher than values reported in similar studies. This highlights the great potential of this co-electrolysis approach for efficient hydrogen production driven by off-grid photovoltaic power. Full article

In the pursuit of addressing the persistent challenge of bacterial adhesion and biofilm formation in dental care, this study investigates the efficacy of electric current as an alternative strategy, specifically focusing on its application in dental contexts. Polyether ether ketone (PEEK), known for its excellent biocompatibility and resistance to bacterial plaque, was enhanced with conductive properties by incorporating silver (Ag), a well-known antibacterial material. Through systematic in vitro experiments, the effectiveness of alternating current (AC) and direct current (DC) in reducing bacterial proliferation was evaluated. The tests were conducted using two bacterial strains: the Gram-positive Staphylococcus aureus and the Gram-negative Pseudomonas aeruginosa. Various configurations, current parameters, and two different electrode configurations were assessed to determine their impact on bacterial reduction. A notable finding from this study is that alternating current (AC) demonstrates superior efficacy compared to direct current (DC). The more significant decrease in CFUs/mL for P. aeruginosa with AC was recorded at the current levels of 5 mA and 500 nA. In opposition, S. aureus exhibited the greatest reduction at 5 mA and 1 mA. This study highlights the potential of using electric current within specific intensity ranges as an alternative strategy to effectively mitigate bacterial challenges in dental care. Full article

Supercapacitors (SCs) are widely acknowledged for their high-power density as energy storage devices; designing electrode materials with both high efficiency and exceptional energy density remains a significant challenge. In this study, a flower-like iron-doped molybdenum sulfide on graphene nanosheets (FMS/G) was synthesized through a simple, efficient, and scalable solvothermal approach. The FMS/G composite demonstrated exceptional performance when employed as both positive and negative electrodes, owing to the effective incorporation of iron into the MoS₂ crystal lattice. This doping induces defects and facilitates abundant redox reactions, ultimately boosting electrochemical performance. The FMS/G composite demonstrates an ultrahigh specific capacitance of 931 F g⁻¹ at 1 A g⁻¹, along with excellent rate capability, retaining 582 F g⁻¹ at 20 A g⁻¹. It also exhibits remarkable cycling stability, maintaining 90.5% of its initial capacitance after 10,000 cycles. Furthermore, the assembled FMS/G-3//FMS/G-3 supercapacitor device achieves a superior energy density of 64.7 Wh kg⁻¹ at a power density of 0.8 kW kg⁻¹ with outstanding cycling stability, retaining 92% of its capacitance after 10,000 cycles. The remarkable capabilities of the flower-like FMS/G composite underscore its noteworthy potential for promoting effective energy storage systems. Full article

In lithium-ion batteries, the fracture of active particles that are under stress is a key cause of battery aging, which leads to a reduction in active materials, an increase in internal resistance, and a decay in battery capacity. A coupled electrochemical–thermal–mechanical model was established to study the concentration and stress distributions of negative electrode particles under different charging rates and ambient temperatures. The results show that during charging, the maximum lithium-ion concentration occurs on the particle surface, while the minimum concentration appears at the particle center. Moreover, as the temperature decreases, the concentration distribution of negative electrode active particles becomes more uneven. Stress analysis indicates that when charging at a rate of 1C and 0 °C, the maximum stress of particles at the negative electrode–separator interface reaches 123.7 MPa, while when charging at 30 °C, the maximum particle stress is 24.3 MPa. The maximum shear stress occurs at the particle center, presenting a tensile stress state, while the minimum shear stress is located on the particle surface, showing a compressive stress state. Finally, to manage the stress of active materials in lithium-ion batteries while charging for health maintenance, this study uses a DNN (Deep Neural Network) to predict the maximum shear stress of particles based on simulation results. The predicted indicators, MAE (Mean Absolute Error) and RMSE (Root Mean Square Error), are 0.034 and 0.046, respectively. This research is helpful for optimizing charging strategies based on the stress of active materials in lithium-ion batteries during charging, inhibiting battery aging and improving safety performance. Full article

With the goal of increasing energy density in lithium–ion cells, new active materials continue to be developed and evaluated. Similarly, in commercial lithium–ion cells, inert materials present in manufactured cells should also be evaluated. The impact of the thickness of inert materials on EV-sized lithium–ion cells was evaluated. The impact of the thicknesses of the positive current collector, negative current collector, separator, and aluminum laminate package on cell properties is presented. The impact of these materials varies greatly over different cell designs, with one of the largest impacts being from a decrease in separator material thickness, especially in cells with a high number of electrode pairs, specifically, cells with a larger thickness or cells with low-capacity loadings. For high-capacity positive electrode loading, a decrease in separator thickness from 16 to 8 microns results in an increase in stack volumetric energy density from 502 to 531 Wh/L or an increase of 5.7%. Full article

This study investigates the feasibility of using a triboelectrostatic belt separator (TBS) as a dry alternative to conventional magnetic separation for concentrating apatite from a phyllosilicate-rich phosphate ore from the Unidade de Mineração de Angico, Brazil. The testing material contained 22.9% P₂O₅ and exhibited over 90% mineral liberation even at coarse fractions (+0.6 mm), being mainly composed of apatite and Mg/Al-bearing phyllosilicates. Pilot-scale experiments were carried out in an M6c TBS, evaluating operational parameters such as electrode polarity, belt speed, feed rate, and electrode gap. In the rougher stage, apatite’s positive charging behavior enabled separation from negatively charged gangue, with optimal conditions (run 4) producing a concentrate of 25.3% P₂O₅ at 85.1% recovery. Cleaner experiments further upgraded product quality, with runs 15 and 18 yielding concentrates of 29.0% and 28.9% P₂O₅ and overall P₂O₅ recoveries of 69.3% and 74.5%, respectively. Compared to high-intensity magnetic separation currently applied at the industrial plant, the TBS achieved superior mass and P₂O₅ recoveries and more effective MgO removal, although Fe₂O₃ and Al₂O₃ contents remained slightly above market thresholds. These results confirm the technical feasibility of triboelectrostatic separation for phosphate beneficiation, offering environmental benefits through reduced water consumption and tailings generation. Further research should focus on finer particle sizes (−0.3 mm), electrode design, and surface charge modifiers to enhance industrial performance. Full article