Search Results (139)

In this work, we employed an easy hydrothermal method to prepare CuO and ZnO, as well as the prepared composite nanostructured electrodes of CuO@ZnO for supercapacitor applications. The systematic electrochemical performance evaluation of the prepared materials was conducted by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). CuO@ZnO nanocomposite reflected the best charge storing behavior with a specific capacitance of 513 F/g, followed by pristine CuO (190 F/g) and ZnO (416 F/g). The composite also demonstrated 25.67 Wh/kg and 400 W/kg for energy density and power density, respectively, suggesting improved electrochemical performance. Besides, the areal and volumetric capacitances were 0.77 F/cm² and 4.81 F/cm³, respectively, supported by the structural integrity and enhancement in electroactive materials utilization of the electrode material. Kinetic analysis showed that b values of the samples had mixed capacitive/diffusion-controlled charge storage, while higher diffusion coefficients and standard rate constants were apparent for ion transport or redox kinetics. EIS results showed a 2.14 Ω solution resistance, indicative of a decreased electrical resistivity. An asymmetric supercapacitor device fabricated by CuO@ZnO as the positive electrode and activated carbon (AC) as the negative electrode provided the specific capacitance of 48.57 F/g, energy density of 15.17 Wh/kg, and power density of 535 W/kg. After 10,000 cycles, the capacitance of the device was 76%, indicating good long-term stability. Full article

Aqueous zinc-ion batteries (AZIBs) are promising for grid-scale storage due to their safety, low cost, and environmental benignity. However, water-dipole enrichment in the inner Helmholtz plane (IHP) of Zn anodes triggers hydrogen evolution, corrosion, and dendrites, limiting cycle life. We report a trace “ionic liquid–polar solvent coupling” strategy: adding only 0.01 M EMIMBF₄ and 0.03 M DMSO to 2 M ZnSO₄ electrolyte. Hydrophobic EMIM⁺ adsorbs on the IHP to expel interfacial water, while BF₄⁻ enters the primary solvation shell and DMSO penetrates both first and second shells of Zn²⁺, forming a water-deficient coordination environment. This interfacial–solvation synergy suppresses parasitic reactions and directs preferentially oriented Zn deposition exclusively along the (101) facet, enabling dense vertical plating and in situ formation of a compact, inorganic-rich SEI (ZnCO₃–ZnSO₃–Zn(OH)₂). Consequently, Zn||Zn cells cycle stably for >5362 h at 1 mA cm⁻²/1 mAh cm⁻²; Zn||Cu cells achieve 1300 cycles with 99.8% average Coulombic efficiency; and Zn||V₂O₅ full cells retain 326.4 mAh g⁻¹ after 500 cycles. This work shows that minimal additive loading can simultaneously engineer the electrode–electrolyte interface and crystallographic deposition pathway, offering a simple yet robust design for ultra-stable AZIBs. Full article

The trace water content in industrial oil critically affects the operational stability and service life of industrial equipment and serves as a key indicator for evaluating oil quality. Therefore, the rapid, sensitive, and visual detection of trace water in oil is of great engineering significance for equipment condition monitoring and early fault warning. Existing detection methods predominantly rely on precision instruments; although they enable quantitative analysis, their operational procedures are complicated and time-consuming, which are unsuitable for on-site real-time monitoring. Consequently, there is an urgent need for a novel trace water detection sensor that offers high sensitivity, visualization, and adaptability to oil-phase environments. Herein, a coplanar electrode alternating current electroluminescent (ACEL) sensor is developed for the visual detection of trace water in oil. The ACEL sensor features a multilayer structure comprising a substrate layer, a coplanar electrode layer, and a humidity-sensitive luminescent layer. The humidity-sensitive luminescent layer consists of humidity-sensitive hydrogel and ZnS: Cu electroluminescent powder, forming a loose and porous film that enables high-sensitivity humidity sensing and simultaneously electroluminescent visual signal output. The sensing mechanism study reveals that variations in trace water content modulate the dielectric properties of the humidity-sensitive layer, which further affect the electroluminescent intensity of the ACEL sensor. In addition, the ACEL sensor enables the rapid, naked-eye recognition of humidity changes under trace water conditions without the need for precision instruments, achieving a rapid response time of 3 s and a detection limit as low as 60 ppm, all making it applicable for different types of industrial oils. Thus, this ACEL sensor features a novel detection mechanism, excellent universality, fast response, and ease of operation, offering a new visual sensing strategy for trace water detection in industrial oil and holding broad prospects for practical applications. Full article

Wire electrical discharge machining (WEDM) is widely used for the precision cutting of difficult-to-machine materials, including nickel-based superalloys. Wire electrode wear, however, remains a practical limitation, because it affects process stability, wire consumption, and machining cost. This work examines the wear behaviour of a gamma-phase Cu₅Zn₈-coated copper-core wire electrode (Elecut X, ø 0.25 mm) during the WEDM of Inconel 718 using direct gravimetric measurement. A 3³ full factorial experiment was carried out with three electrical parameters: pulse-on time (A), pulse-off time (B), and servo reference voltage (Aj). The discharge process was monitored with an oscilloscope so that measurements only started after the programmed pulse-off time had been reached. Electrode wear was evaluated as the mass loss Δm of 4 m wire segments after 5 min cutting intervals on a Charmilles Robofil 310 machine, and factor significance was assessed by analysis of variance (ANOVA). Pulse-on time was the dominant factor, accounting for 88.45% of the total variation in Δm, followed by servo reference voltage and pulse-off time. SEM/EDS examination showed material transfer from the Inconel 718 workpiece to the worn electrode surface, with local nickel content reaching 16.84 wt.% on the frontal face of the most worn sample. The results provide a quantitative basis for reducing wire consumption during the WEDM of Inconel 718 while recognising the trade-off with cutting productivity. Full article

Using strategies employed in synthetic chemistry, we investigated the chemicals found in lithium iron phosphate (LFP) spent battery via an initial dichloromethane (DCM) extraction of the individual cathode and anode. The pre- and post-treated electrodes and DCM extracts were examined using a range of analytical techniques. A total of 26 compounds were identified, which included the following: (1) some of the benchmark materials, LFP, lithium hexafluorophosphate (LIPF₆), polyvinylidene fluoride (PVDF), graphite and carbon black; (2) NMR spectroscopy of DCM extract revealed five main chemicals, which were ethylene and propylene carbonate solvents, LiPF₆, lithium tetrafluoroborate (LiBF₄), and an unknown fluorochemical; (3) analysis of the water-treated DCM extract revealed 21 chemicals by GCMS, several fluorochemicals; (4) 12 chemicals were found in both cathode and anode and three only in the anode; (5) only 13 of the 21 chemicals could be properly named, whilst four had some notable functionality and three could not be identified; and (6) ICP analysis revealed high levels of Al, Cu, Fe, V, and Zn in both electrodes and spent electrolyte. The high number of chemicals present in the spent electrolyte and electrodes suggest battery manufacturers use many proprietary chemicals to enhance battery properties. This procedure allows insight and identification of chemicals present in waste LIBs which will require advanced chemical techniques to recover high yields and purity of recycled materials and the need to dispose of hazardous waste. Full article

Soil penetration resistance (Pr) measurement is important for assessing compaction and permeability; however, Pr is heavily dependent on soil moisture. Therefore, the interpretation of Pr data is significantly more reliable if moisture is measured simultaneously and in the same soil layer. In addition, reliable assessment of permeability requires consideration of both soil moisture and penetration resistance. The aim of this work was to develop a prototype of a hand-held combined device in which a volumetric moisture sensor operating on the principle of a galvanic cell is integrated into the Pr measurement cycle, allowing simultaneous measurements at different depths. The device simultaneously determined the penetration resistance acting on the cone, the measurement depth (with a laser sensor), the volumetric moisture (Cu–Zn electrode pair), and the location of the measurement site (GNSS). The moisture sensor was found to be neutral to the influence of the mineral part of the soil on moisture measurement, which in the case of other alternative measurement methods significantly affects the soil moisture measurement data. The calibration of the galvanic moisture sensor was performed under laboratory conditions (VWC 5–50%) based on a gravimetric reference. The relationship was approximately linear at lower moistures and nonlinear at higher moistures. The salinity effect test indicated that the TDR-based reference device gave a strongly overestimated moisture reading in saline soil, while the galvanic cell-based measurement remained within a realistic range compared to the gravimetric method. The results indicate that Pr measurement integrated with a galvanic sensor creates a practical prerequisite for the simultaneous collection of Pr and moisture profiles and is useful in conditions where dielectric methods are affected by salinity or minerality interference. Full article

The purpose of any electrode in die-sinking EDM is to transmit electrical impulses that facilitate workpiece erosion with minimum or no self-erosion. The performance of the electrode depends on the properties of the material that it is made of, application, and the workpiece material. This study focused on employing intensive machining regimes that increase productivity while maintaining electrode wear as low as possible to enhance cost-effectiveness. The experimental tests were organized using the response surface method and the analysis of the results is based on the ANOVA method. The findings revealed that the WCu 75/25 outperforms the other two in wear resistance and CuZn39Pb2 is the most wear prone. It was revealed that WCu 75/25 electrode at Ip ≈ 90 A and Ton between 360 and 390 µs represents the globally best solution for a minimum wear. Full article

In this work, a novel nanostructured Mn₃O₄-based electrochemical sensor was developed for the determination of heavy metals in aqueous media. The Mn₃O₄ nanostructure was solvothermally synthesized in the sole presence of propylene glycol (PG). Under the specific synthetic conditions, PG provided surface coating and stabilization by decomposition products and/or residual PG molecules that have been adsorbed on Mn₃O₄ NPs surfaces, creating a thin organic layer. This imparts a negative surface charge (zeta potential), enhancing colloidal stability in dispersions and electrochemical performance. The physicochemical properties of the resulting NPs were characterized via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Thermogravimetric Analysis (TGA), and Dynamic light scattering (DLS) and ζ-potential measurements, as well as SEM imaging of the modified electrode surface, confirming its successful formation and favorable structural properties. The LODs of Cd²⁺, Pb²⁺, Zn²⁺, and Cu²⁺ for their simultaneous determination are 2.9 μg·L⁻¹, 5.2 μg·L⁻¹, 7.1 μg·L⁻¹, and 2.5 μg·L⁻¹, respectively, with relative standard deviations of about 5.24%, 4.43%, 7.74%, and 4.53%, respectively. As a result of this study, a simple, sensitive, and reproducible electrochemical sensor based on a carbon paste electrode (CPE) modified with novel synthesized manganese nanoparticles and employing voltammetric techniques was applied in water and wastewater. Full article

Nitrate pollution in groundwater poses severe threats to ecosystems and human health, making the electrochemical nitrate reduction reaction (NO₃RR) a promising remediation technology. Conductive metal–organic frameworks (cMOFs) with π-d conjugation, dispersed active sites, and tunable structures are ideal candidates for electrocatalysis. Herein, we synthesized a series of cMOFs (M₃(HHTP)₂, M = Fe, Zn, Cu, Co, Ni) via conjugated coordination between hexahydroxytriphenylene (HHTP) ligands and metal ions and systematically investigated their NO₃RR performance. Electrochemical tests revealed that Fe₃(HHTP)₂ exhibits superior catalytic performance for nitrate reduction, achieving a high NH₃ selectivity of 99.5% and a yield rate of 676.4 mg·g_cat⁻¹·h⁻¹ at −1.0 V vs. RHE (reversible hydrogen electrode), along with excellent cyclic and structural stability. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy identified key intermediates (*NO₂, *NH₂OH) and proposed the reaction pathway: NO₃⁻ → *NO₃ → *NO₂ → *NO → *NOH → *NH₂OH → *NH₂ → *NH₃. DFT calculations revealed that Fe center exhibited a lower energy barrier for NO₃RR compared to other metal ions (Zn, Cu, Co, Ni). This study demonstrates the significant potential of Fe₃(HHTP)₂ for efficient NO₃RR and provides new insights into the structure-function relationship of cMOF-based electrocatalysts. Full article

Low-voltage primary batteries broadly power small electronics used in health, biomedical, and wearable applications. These devices are generally more sensitive to volumetric capacity than gravimetric capacity. The current state-of-the-art button battery is Zn-Ag₂O, where contributors that limit volumetric capacity include the incorporation of inactive materials in the electrode microstructure such as gelling agents, binders, and conductive additives. Herein, cathode materials of CuO and FeS₂ will be described for small form factor coin/button cells. When paired with Li metal anodes, the operating voltage is similar to Zn-Ag₂O. The key innovation is that they will be processed into all-active-material (AAM) electrode architectures, where the electrodes will comprise only electroactive materials and pores that are filled with electrolyte during cell fabrication. The AAM architecture significantly enhanced electroactive material volume utilization, and thus volumetric capacity. FeS₂ and CuO were processed into AAM electrodes under various processing conditions, and Li-FeS₂ and Li-CuO primary batteries were fabricated and evaluated. At the cell level, volumetric capacity of 1300 mAh cm⁻³ was achieved, and in a button cell form factor 395/927, nearly 100 mAh was delivered, which compares favorably with commercially available options, which typically range from 27 to 55 mAh. Full article

In recent years, electrochemical pressure (ECP) sensors with self-powered and both dynamic and static pressure detection capabilities have received widespread attention. To improve pressure sensing performances while reducing the thickness of conventional sandwich structure ECP sensors, we propose an ECP sensor with a simple electrode coplanar structure. Specifically, it consists of Cu/Zn foil electrodes and LiCl/polyvinyl alcohol (PVA) modified filter paper. Among them, the Cu/Zn coplanar electrodes are used for redox reactions, the LiCl provides conductive ions, and the PVA is used to provide a humid environment to promote the ionization and conduction of LiCl. The rough surface microstructure of the filter paper is used to enhance the pressure sensing performances of the sensor. The results show that the ECP sensor with an electrode coplanar structure can spontaneously output current in the pressure range of 0.4–100 kPa, with sensitivities of 0.273 kPa⁻¹ (0.6–20 kPa) and 0.036 kPa⁻¹ (20–100 kPa). Specifically, compared to ECP sensors with a sandwich structure, it has a wider response range and higher sensitivity. Through the current response, morphological characterizations, and redox reactions, the pressure sensing mechanism is elucidated. Furthermore, the proposed ECP sensor can be used for respiratory state recognition combined with machine learning. This research provides a new approach for developing a high-performance ECP sensor with a simple electrode coplanar structure. Full article

Reducing electrode-related costs is an important step toward the large-scale commercialization of polymer solar cells. In this study, Cu is investigated as a low-cost top electrode in inverted polymer solar cells with the architecture ITO/ZnO/P3HT:PCBM/MoO₃/Cu. The fabricated devices achieved a maximum power conversion efficiency (η) of 2.86%, with an open-circuit voltage (V_oc) of 610 mV, a short-circuit current density (J_sc) of 6.90 mA cm⁻², and a fill factor (FF) of 68%. Long-term stability tests were carried out over a period of 12 weeks under glovebox, desiccator, and ambient room conditions, during which efficiency decreases of 23%, 53%, and 78% were observed, respectively. Structural and spectroscopic analyses suggest that device degradation is closely associated with O₂- and moisture-induced effects on the Cu electrode. The results demonstrate that Cu can be effectively employed as a top electrode in polymer solar cells under controlled environmental conditions, highlighting its potential as a cost-effective electrode material for polymer solar cell applications. Full article

The electrochemical reduction of CO₂ to ethanol represents a sustainable alternative to recycle CO₂ into a value-added product, yet achieving high selectivity and efficiency remains a challenge. This work explores Cu-based catalysts supported on SiO₂ and ZrO₂, with and without ZnO doping, for ethanol production in a continuous flow-cell system. Gas diffusion electrodes are fabricated using commercial catalysts with varying Cu loadings (5–10%) and ZnO contents (2–3.5%). Comprehensive characterization by XPS confirms the presence of Cu²⁺ and Zn²⁺ species, while SEM reveals that ZnO incorporation improves surface uniformity and aggregate distribution compared to undoped samples. Electrochemical tests demonstrate that 10% Cu on SiO₂ achieves a Faradaic efficiency of 96% for ethanol at −3 mA cm⁻², outperforming both doped catalysts and previously reported materials. However, efficiency declines at higher current densities, indicating a trade-off between selectivity and productivity. ZnO doping enhances C₂⁺ product formation but does not surpass the undoped catalyst in ethanol selectivity. These results underline the importance of catalyst composition, support interactions, and operating conditions, and point to further optimization of electrode architecture and cell configuration to sustain high ethanol yields under industrially relevant conditions. Full article

Metal oxide nanomaterials have emerged as transformative materials in the quest to enhance the energy density and overall performance of lithium-ion batteries (LIBs) and solid-state batteries (SSBs). Their unique properties—including their large surface areas and short ion diffusion pathways—make them ideal for next-generation energy storage technologies. In LIBs, the high surface-to-volume ratio of metal oxide nanomaterials significantly enlarges the active interfacial area and shortens the lithium-ion diffusion paths, leading to an improved high-rate performance and enhanced energy density. Transition metal oxides (TMOs) such as nickel oxide (NiO), copper oxide (CuO), and zinc oxide (ZnO) have demonstrated significant theoretical capacities, while binary systems like NiCuO offer further improvements in cycling stability and energy output. Additionally, layered lithium-based TMOs, particularly those incorporating nickel, cobalt, and manganese, have shown remarkable promise in achieving high specific capacities and long-term stability. The synergistic integration of metal oxides with carbon-based nanostructures, such as carbon nanotubes (CNTs), enhances the electrical conductivity and structural durability further, leading to a superior electrochemical performance in LIBs. In SSBs, the use of oxide-based solid electrolytes like garnet-type Li₇La₃Zr₂O₁₂ (LLZO) and sulfide-based electrolytes has facilitated the development of high-energy-density systems with excellent ionic conductivity and chemical stability. However, challenges such as high interfacial resistance at the electrode–electrolyte interface persist. Strategies like the application of lithium niobate (LiNbO₃) coatings have been employed to enhance interfacial stability and maintain electrochemical integrity. Furthermore, two-dimensional (2D) metal oxide nanomaterials, owing to their high active surface areas and rapid ion transport, have demonstrated considerable potential to boost the performance of SSBs. Despite these advancements, several challenges remain. Morphological optimization of nanomaterials, improved interface engineering to reduce the interfacial resistance, and solutions to address dendrite formation and mechanical degradation are critical to achieving the full potential of these materials. Full article

The Cu₂O-based photocathode has been widely applied in photoelectrocatalytic hydrogen evolution and carbon dioxide reduction systems. However, the poor stability of Cu₂O caused by photocorrosion highly restricts the application. In this work, a multilayer configuration is designed as Cu₂O/ZnO/SnO₂ via sequential depositions of electrodeposition and spin-coating. The liquid-phase epitaxial growths of the Cu₂O and ZnO layers are achieved by sequential electrodepositions on a FTO/Au substrate. The decoration of a uniform SnO₂ layer onto Cu₂O/ZnO is realized by a SnO₂ QDs coating and provides dual functions for boosted electron transfer and surface reaction. The protection of the SnO₂ layer is fulfilled by the inhibition of Cu⁺ transformation, resulted from the compact covering of SnO₂ QDs onto the exposed surface of the Cu₂O and ZnO layers. Consequently, the enhanced photocurrent density and improved stability are obtained for Cu₂O/ZnO/SnO₂ compared to bare Cu₂O and Cu₂O/ZnO sample photocathodes. The necessary role of SnO₂ QDs serving as electron transfer and protection layers studied in this work reveals the remarkable potential in the modification of other vulnerable electrode materials. Full article