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In the realm of electrochemical nitrite detection, the potent oxidizing nature of nitrite typically necessitates operation at high detection potentials. However, this study introduces a novel approach to address this challenge by developing a highly sensitive electrochemical sensor with a low reduction detection potential. Specifically, a copper metal nanosheet/carbon paper sensitive electrode (Cu/CP) was fabricated using a one-step electrodeposition method, leveraging the catalytic reduction properties of copper's high occupancy d-orbital. The Cu/CP sensor exhibited remarkable performance in nitrite detection, featuring a low detection potential of −0.05 V vs. Hg/HgO, a wide linear range of 10~1000 μM, an impressive detection limit of 0.079 μM (S/N = 3), and a high sensitivity of 2140 μA mM−1cm−2. These findings underscore the efficacy of electrochemical nitrite detection through catalytic reduction as a means to reduce the operational voltage of the sensor. By showcasing the successful implementation of this strategy, this work sets a valuable precedent for the advancement of electrochemical low-potential nitrite detection methodologies. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for paraquat determination was facilely developed using nanocomposites of cellulose incorporated with manganese oxide (MnO2@cellulose) modified screen-printed carbon electrode (SPCE). In this study, SPCE was fabricated on a low-cost poster paper, and nanocellulose from sugarcane bagasse was employed to enhance the electrode's surface area and improve the dispersion of MnO2. The MnO2@cellulose modified poster-SPCE exhibited a high electrochemical response toward paraquat. Various influencing factors, including differential pulse voltammetric parameters and accumulation time, were systematically explored. Under the optimal conditions, the cathodic peak current was linearly proportional to paraquat concentration in a range of 2 to 200 µM, featuring a low detection limit of 1 µM. The proposed sensor offers cost-effectiveness and can be readily prepared via a simple procedure. Moreover, this method exhibits excellent reproducibility, high selectivity, and a short analysis time. The portable electrochemical sensor was able to determine paraquat in water samples with acceptable recoveries from 95.45 to 109.20%, indicating that the sensor based on MnO2@cellulose/SPCE is reliable for paraquat quantification. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are expected to be one of the next generations of high-energy-density battery systems due to their high theoretical energy density of 2600 Wh kg−1. Embracing the trends toward flexibility, lightweight design, and cost-effectiveness, paper-based electrodes offer a promising alternative to traditional coated cathodes in Li–S batteries. Within paper-based electrodes, conductive fibers such as carbon nanotubes (CNTs) play a crucial role. They help to form a three-dimensional network within the paper matrix to ensure structural integrity over extended cycling while mitigating the shuttle effect by confining sulfur within the cathode. Herein, we explore how variously functionalized CNTs, serving as conductive fibers, impact the physical and electrochemical characteristics of paper-based sulfur cathodes in Li–S batteries. Specifically, graphitized hydroxylated carbon nanotubes (G-CNTs) exhibit remarkable capacity at low currents owing to their excellent conductivity and interaction with lithium polysulfide (LiPS), achieving the highest initial specific capacity of 1033 mAh g−1 at 0.25 C (1.1 mA cm−2). Aminated multi-walled carbon nanotubes (NH2-CNTs) demonstrate an enhanced affinity for LiPS due to the -NH2 groups. However, the uneven distribution of these fibers may induce electrode surface passivation during charge–discharge cycles. Notably, hydroxylated multi-walled carbon nanotubes (OH-CNTs) can establish a uniform and stable 3D network with plant fibers, showcasing superior mechanical properties and helping to mitigate Li2S agglomeration while preserving the electrode porosity. The paper-based electrode integrated with OH-CNTs even retains a specific capacity of approximately 800 mAh g−1 at about 1.25 C (5 mA cm−2), demonstrating good sulfur utilization and rate capacity compared to other CNT variants. [ABSTRACT FROM AUTHOR]

The development of nanohybrid with high electrocatalytic activity is of great significance for electrochemical sensing applications. In this work, we develop a novel and facile method to prepare a high-performance flexible nanohybrid paper electrode, based on nitrogen-doped carbon (NC) wrapped Bi nanoparticles (Bi-NPs) assembly derived from Bi-MOF, which are decorated on a flexible and freestanding graphene paper (GP) electrode. The as-obtained Bi-NPs encapsulated by an NC layer are uniform, and the active sites are increased by introducing a nitrogen source while preparing Bi-MOF. Owing to the synergistic effect between the high conductivity of GP electrode and the highly efficient electrocatalytic activity of Bi-NPs, the NC wrapped Bi-NPs (Bi-NPs@NC) modified GP (Bi-NPs@NC/GP) electrode possesses high electrochemically active area, rapid electron-transfer capability, and good electrochemical stability. To demonstrate its outstanding functionality, the Bi-NPs@NC/GP electrode has been integrated into a handheld electrochemical sensor for detecting heavy metal ions. The result shows that Zn2+, Cd2+, and Pb2+ can be detected with extremely low detection limits, wide linear range, high sensitivity, as well as good selectivity. Furthermore, it demonstrates outstanding electrochemical sensing performance in the simultaneous detection of Zn2+, Cd2+, and Pb2+. Finally, the proposed electrochemical sensor has achieved excellent repeatability, reproducibility, stability, and reliability in measuring real water samples, which will have great potential in advanced applications in environmental systems. [ABSTRACT FROM AUTHOR]

Herein, we evaluated the use of paper towel, waxed paper, and Parafilm M® (Heathrow Scientific, Vernon Hills, IL, USA) as alternative substrates for screen-printed sensor manufacturing. Morphological study was performed to evaluate the adhesion of the ink on these uncommon substrates, as well as the morphology of the working electrode. The electrochemical characterization was carried out using ferricyanide/ferrocyanide as redox couple. To enhance the electrochemical properties of the developed sensors, the nanomaterial carbon black was used as nanomodifier. The modification by drop casting of the working electrode surface, using a stable dispersion of carbon black, allows to obtain a sensor with improved electrochemical behavior in terms of peak-to-peak separation, current intensity, and the resistance of charge transfer. The results achieved confirm the possibility of printing the electrode on several cost-effective paper-based materials and the improvement of the electrochemical behavior by using carbon black as sustainable nanomaterial. [ABSTRACT FROM AUTHOR]

Electrochemical dilatometry is used to investigate Li plating/stripping on Cu foil and porous carbon paper substrates. Experiments are performed in standard electrolyte for Li–S batteries at a current density of 1 mA cm−2 with a Li plating charge fixed at 1 mAh cm−2. A fully dense Li film (4.8 μm thick) is initially electrodeposited on the Cu electrode. However, from the 2nd Li plating/stripping cycle, Li deposit becomes porous to reach a thickness of 9.6 µm at the 27th cycle, corresponding to a film porosity of 50%, favoring its collapse during the subsequent cycles. When a carbon paper with a low surface area (0.02 m2 g−1) is used as a substrate, Li deposition occurs preferentially in the pores of the carbon paper during the first few cycles. However, this does not prevent the formation of Li dendrites, which progressively extend on the top of the substrate, resulting in the degradation of the electrode cyclability after about 40 cycles. The use of a carbon paper with a higher surface area (4.2 m2 g−1) favors Li deposition inside the electrode, with no apparent loss of cyclability after 50 cycles. However, this does not prevent the formation of dead Li, as suggested by the continuous and irreversible expansion of the electrode over cycling at a mean rate of 1.3 μm per cycle. Additionally, a large and irreversible expansion of 38 μm is observed during the first cycle, which is attributed to the lithium-solvent co-intercalation in the graphitic part of the carbon paper substrate. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li 2 S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe 2 O 4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe 2 O 4 nanoparticles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/CoFe 2 O 4 /CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g−1 and remaining a high reversible capacity of 642.6 mAh g−1 after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. The bimetallic oxide CoFe 2 O 4 nanoparticles anchored on the carbon nanotube paper is proposed as free-standing sulfur host with enhanced polysulfide trapping and catalytic effects for advanced Li-S batteries. [Display omitted] • Binder-free host realizes high sulfur loading and energy density for Li-S battery. • CoFe 2 O 4 /CNT paper inhibits the polysulfide shuttling via strong chemical interaction. • CNT-anchored CoFe 2 O 4 catalytically promotes the polysulfide conversion kinetics. • The Li-S battery with S/CoFe 2 O 4 /CNT cathode exhibits enhanced capacity and stability. [ABSTRACT FROM AUTHOR]

Purified paper was prepared from UHT milk packaging waste and firstly applied as a novel electrochemical sensor by chemical modification using alkali treatment, whereas 0.25–1 g of aluminum foil was dissolved into solvent. The purified paper was then immersed into aluminum solution. The existence of aluminum was found on purified cellulose paper. The mapping experiment was reported the aluminum was uniformly distributed onto purified cellulose. It was thermally stable up to 200 °C. The surface roughness of conductive paper was found to be 20–30 micron. A significant conductivity enhancement of purified cellulose was caused by the presence of aluminum. 1 g of aluminum in solution provided the excellent electrochemical conductivity measured by both cyclic voltammetry and electrochemical impedance spectroscopy, verifying that this material might be an alternative candidate as a novel paper-based electrode in electrochemical sensor. [ABSTRACT FROM AUTHOR]

Current 3D printed electrodes suffer from insufficient multiscale transport speed, which limits the improvement of electrochemical performance of 3D printed electrodes. Herein, a bioinspired hierarchical fast transport network (HFTN) in a 3D printed reduced graphene oxide/carbon nanotube (3DP GC) electrode demonstrating superior electrochemical performance is constructed. Theoretical calculations reveal that the HFTN of the 3DP GC electrode increases the ion transport rate by more than 50 times and 36 times compared with those of the bulk GC electrode and traditional 3DP GC (T‐3DP GC) electrode, respectively. Compared with carbon paper, carbon cloth, bulk GC electrode, and T‐3DP GC electrode, the HFTN in 3DP GC electrode endows obvious advantages: i) efficient utilization of surface area for uniform catalysts dispersion during electrochemical deposition; ii) efficient utilization of catalysts enables the high mass activity of catalysts and low overpotential of electrode in electrocatalytic reaction. The cell of 3DP GC/Ni‐NiO||3DP GC/NiS2 demonstrates a low voltage of only 1.42 V to reach 10 mA cm−2 and good stability up to 20 h for water splitting in alkaline conditions, which is superior to commercialized Pt/C||RuO2. This work demonstrates great potential in developing high‐performance 3D printed electrodes for electrochemical energy conversion and storage. [ABSTRACT FROM AUTHOR]

• In-situ growth of MoS 2 over MnCO 3 inhibits formation of Mn-oxides/hydroxide. • MnCO 3 transforms to Mn(OH) 2 in aqueous KOH and stores charge by redox processes. • Mn(OH) 2 and MoS 2 afford low diffusion and charge transfer resistances, respectively. • MnCO 3 @MoS 2 hybrid utilized as negative electrode in asymmetric supercapacitor. This article puts forward a novel approach of combining the battery-type charge storage material, Mn(OH) 2 , indirectly with the two-dimensional material, MoS 2 , to develop the composite MnCO 3 @MoS 2 (designated as MCMS). A single-step facile hydrothermal method is described here for the synthesis of MCMS on a low-cost graphite substrate. Furthermore, this as-synthesized binder-free electrode is utilized as the negative electrode of an all-solid state asymmetric alkaline supercapacitor, employing NiCo 2 O 4 as the high specific energy positive electrode material. The overall asymmetric cell is shown to achieve a high specific energy of 48.97 W.h.kg −1 at 600 W.kg −1 and a high specific power of 12 kW.kg −1 at 11.33 W.h.kg −1, within a potential window of 1.2 V. Also, the composite electrode notably retains 86.5% of its gravimetric discharge capacity after 10,000 cycles with complete retention of its coulombic efficiency. The present work contributes to the development of a facile strategy for the preparation of non-carbonaceous hybrid materials suitable for high specific energy negative electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Computer numerical control printed disposable paper electrodes for electrochemical sensing. • Proof-of-concept demonstrated by detecting Pseudomonas aeruginosa virulence factor pyocyanin. • Satisfactory analytical performance and validated with gold standard. Disposable paper electrodes (PPE) have significant advantages in biosensor research considering the cost-effectiveness, simplicity, and easy batch manufacturing opportunity. An increase in communicable and non-communicable diseases demands for custom-made sensor platforms. Herein, we report an alternative method for the fabrication of PPE through simple and rapid computer numerical controlled (CNC) printing technique. The fabricated electrodes were electrochemically characterised, and by detecting antibiotic resistant pathogen, Pseudomonas aeruginosa virulence factor pyocyanin, the sensing application is demonstrated. Finally, the sensor is validated with a gold-standard culture-based assay. [ABSTRACT FROM AUTHOR]

Large-capacitance and ultrahigh-rate electrochemical supercapacitors (UECs) with frequency response up to kilohertz (kHz) range are reported using light, thin, and flexible freestanding electrodes. The electrode is formed by perpendicularly edge oriented multilayer graphene/thin-graphite (EOG) sheets grown radially around individual fibers in carbonized cellulous paper (CCP), with cellulous carbonization and EOG deposition implemented in one step. The resulted ∼10 μm thick EOG/CCP electrode is light and flexible. The oriented porous structure of EOG with large surface area, in conjunction with high conductivity of the electrode, ensures ultrahigh-rate performance of the fabricated cells, with large areal capacitance of 0.59 mF cm −2 and 0.53 mF cm −2 and large phase angle of −83° and −80° at 120 Hz and 1 kHz, respectively. Particularly, the hierarchical EOG/CCP sheet structure allows multiple sheets stacked together for thick electrodes with almost linearly increased areal capacitance while maintaining the volumetric capacitance nearly no degradation, a critical merit for developing practical faraday-scale UECs. 3-layers of EOG/CCP electrode achieved an areal capacitance of 1.5 mF cm −2 and 1.4 mF cm −2 at 120 Hz and 1 kHz, respectively. This demonstration moves a step closer to the goal of bridging the frequency/capacitance gap between supercapacitors and electrolytic capacitors. [ABSTRACT FROM AUTHOR]

A CO 2 laser can be used to pyrolyze the surface of common paperboard to produce a conductive carbon material for subsequent use as an electrode for general electrochemical measurements. In this work, a laser-pyrolyzed electrochemical paper-based analytical device (LP-ePAD) of this type was combined with a gas-diffusion microextraction (GDME) unit for the square-wave voltammetric analysis of sulphites in commercial beverages. The fabricated LP-ePAD had a resistivity at room temperature of 11 ± 4 Ω per square electrical sheet (measured with a four-point probe system). The developed methodology showed a limit of detection of 1 mg L−1 for sulphite analysis, with good repeatability and reproducibility (coefficient of variation below 7%), as well having as the desirable qualities of portability and low price. Unlabelled Image • Electroanalysis using low-cost pyrolyzed electrochemical paper-based analytical sensor. • Paper electrodes are fabricated using a CO 2 laser in a single reagentless step. • The paper electrodes had a sheet resistivity of ca. 11 Ω/sq. [ABSTRACT FROM AUTHOR]

Electrode‐assisted techniques are well suited for the separation of ions from solutions with reduced energy and chemical consumption. This emerging platform can benefit greatly from the convection enhanced and zero‐gap reactor designs unlocked by macroporous electrodes, but immobilizing ion‐selective layers on such complex 3D architectures is challenging. Electropolymerization of conductive polymers is proposed as a coating methodology to fabricate highly conformal coatings with electrochemically switchable ion‐exchange functionality. To demonstrate this, the synthetic parameters, resulting morphology, and ionic separation performance of poly(3,4‐ethylenedioxythiophene) (PEDOT) on commercially available carbon paper electrodes are studied. Electropolymerization of PEDOT in organic solvents results in rougher morphologies with high sensitivity to electrochemical protocols employed. When polymerized in aqueous solutions of poly(4‐styrenesulfonate) (PSS−), the resulting PEDOT/PSS blend polymer forms smooth coatings with a controllable thickness down to 0.1 µm. With appropriate voltage bias, PEDOT/PSS coated electrodes can take up and release Ni2+ in the presence of excess Na+. Increasing the coating thickness decreases the adsorption capacity due to mass transfer limitations, and the maximum adsorption capacity for Ni2+ is reached for the thinnest coatings at 228 mg g−1. Through a systematic study of PEDOT/PSS coated carbon paper, electropolymerization is identified to be a promising avenue for porous electrode functionalization. [ABSTRACT FROM AUTHOR]

The use of fully printed electrochemical devices has gained more attention for the monitoring of clinical, food, and environmental analytes due to their low cost, great reproducibility, and versatility characteristics, serving as an important technology for commercial application. Therefore, a paper-based inkjet-printed electrochemical system is proposed as a cost-effective analytical detection tool for paraquat. Chromatographic paper was used as the printing substrate due its sustainable and disposable characteristics, and an inkjet-printing system deposited the conductive silver ink with no further modification on the paper surface, providing a three-electrode system. The printed electrodes were characterized with scanning electron microscopy, cyclic voltammetry, and chronopotentiometry. The proposed sensor exhibited a large surface area, providing a powerful tool for paraquat detection due to its higher analytical signal. For the detection of paraquat, square-wave voltammetry was used, and the results showed a linear response range of 3.0–100 μM and a detection limit of 0.80 µM, along with the high repeatability and disposability of the sensor. The prepared sensors were also sufficiently selective against interference, and high accuracy (recovery range = 96.7–113%) was obtained when applied to samples (water, human serum, and orange juice), showing the promising applicability of fully printed electrodes for electrochemical monitoring. [ABSTRACT FROM AUTHOR]

A proton exchange membrane fuel cell (PEMFC) is an efficient and environmentally friendly power production technology that uses hydrogen energy. The cathodic oxygen reduction electrode is a critical component in the development of PEMFC. Most techniques deposit catalyst nanoparticles in areas that are inaccessible for catalytic processes, reducing platinum utilization. The substrate used in this study was carbon paper (CP) with a self-supporting structure. First, electrochemical acidification technology was employed to modify the CP's surface, followed by nanoparticle manufacturing and fixation on the CP in a single step by electrodeposition. The Pt/C0.5V2.24CP catalyst electrode demonstrated high-quality activity in the oxygen reduction reaction (ORR), with a homogeneous particle dispersion and particle size of around 50 nm. The mass activity and electrochemical active surface area (ECSA) of the Pt/C0.5V2.24CP catalyst electrode were 1.74 and 3.98 times higher than those of the Pt/C/CP-1 electrodes made with commercial catalysts, respectively. After 5000 cycles of accelerated durability testing (ADT), the mass activity and ECSA were 1.28 times and 6.16 times more than Pt/C/CP-1. This paper successfully proved the viability of electrodepositing Pt nanoparticles on CP following acidification, and that the electrochemical acidification methods have a positive influence on improving electrode ORR activity. [ABSTRACT FROM AUTHOR]

Flexible screen-printed electrodes (HP) were fabricated on stone paper substrate and amperometrically modified with gold nanoparticles (HP-AuNPs). The modified electrode displayed improved electronic transport properties, reflected in a low charge-transfer resistance (1220 Ω) and high apparent heterogeneous electron transfer rate constant (1.94 × 10−3 cm/s). The voltammetric detection of dopamine (DA) was tested with HP and HP-AuNPs electrodes in standard laboratory solutions (pH 6 phosphate-buffered saline (PBS)) containing various concentrations of analyte (10−7–10−3 M). As expected, the modified electrode exhibits superior performances in terms of linear range (10−7–10−3 M) and limit of detection (3 × 10−8 M), in comparison with bare HP. The determination of DA was tested with HP-AuNPs in spiked artificial urine and in pharmaceutical drug solution (ZENTIVA) that contained dopamine hydrochloride (5 mg/mL). The results obtained indicated a very good DA determination in artificial urine without significant matrix effects. In the case of the pharmaceutical drug solution, the DA determination was affected by the interfering species present in the vial, such as sodium metabisulfite, maleic acid, sodium chloride, and propylene glycol. [ABSTRACT FROM AUTHOR]

The interfacial effect is important for anodes of transition metal dichalcogenides (TMDs) to achieve superior lithium-ion storage performance. In this paper, a MoS2/FeS2 heterojunction is synthesized by a simple hydrothermal reaction to construct the interface effect, and the heterostructure introduces an inherent electric field that accelerates the de-embedding process of lithium ions, improves the electron transfer capability, and effectively mitigates volume expansion. XPS analysis confirms evident chemical interaction between MoS2 and FeS2 via an interfacial covalent bond (Mo–S–Fe). This MoS2/FeS2 anode shows a distinct interfacial effect for efficient interatomic electron migration. The electrochemical performance demonstrated that the discharge capacity can reach up to 1217.8 mA h g−1 at 0.1 A g−1 after 200 cycles, with a capacity retention rate of 72.9%. After 2000 cycles, the capacity retention is about 61.6% at 1.0 A g−1, and the discharge capacity can still reach 638.9 mA h g−1. Electrochemical kinetic analysis indicated an enhanced pseudocapacitance contribution and that the MoS2/FeS2 had sufficient adsorption of lithium ions. This paper therefore argues that this interfacial engineering is an effective solution for designing sulfide-based anodes with good electrochemical properties. [ABSTRACT FROM AUTHOR]

Both polyaniline (PANI) and graphene are widely studied for their application as capacitive electrodes in energy storage devices. However, although PANI can be easy synthesized, is of low cost and has a higher specific capacitance than graphene, pristine PANI electrodes do not present long-term stability due to their large volume changes during release/doping of the electrolyte ions and surface area reduction with charge-discharge cycling. That is why a combination of PANI with carbonaceous materials, especially conductive and high-surface-area graphene as well as more widely used reduced graphene oxide (rGO), provides an effective approach to solve these problems. At the same time, the electropolymerization process is one of the possible methods for synthesis of PANI composites with G or rGO as freestanding electrodes. Therefore, no binders or additives such as carbon black or active carbon need to be used to obtain PANI/rGO electrodes by electrochemical polymerization (EP), in contrast to similar electrodes prepared by the chemical oxidative polymerization method. Thus, in this paper, we review recent advances in EP synthesis of PANI/rGO nanocomposites as high-performance capacitive electrode materials, combining the advantages of both electrical double-layer capacitance of rGO and pseudocapacitance of PANI, which hence exhibit long cycle life and high specific energy. [ABSTRACT FROM AUTHOR]

This study investigates nitrogen-doped carbon synthesis and electrochemical properties as electrode material for energy storage devices, an additional focus of the work is on the electrochemical exfoliation synthesis of nitrogen-doped carbon using various precursors and doping methods. The physical properties of the synthesized sample are characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, and Raman spectroscopy. The electrochemical properties of the N-doped carbons are studied using cyclic voltammetry and galvanostatic charge-discharge cycling. Finally, the work explores the potential application of the N-doped carbons as electrode material for energy storage devices, such as supercapacitors. The results show that N-doped carbons exhibit electrochemical performance superior to that of graphene oxide, with higher electrical capacitance. The results demonstrate the potential of N-doped carbons as high-performance electrode materials for electrochemical energy storage applications. This paper aims to explain the advantages of N-doping in carbon materials more precisely in graphene and the use of these materials in creating electrodes for application in supercapacitors and batteries. [ABSTRACT FROM AUTHOR]

Ni-rich Li(NixCoyMnz)O2 (x ≥ 0.8)-layered oxide materials are highly promising as cathode materials for high-energy-density lithium-ion batteries in electric and hybrid vehicles. However, their tendency to undergo side reactions with electrolytes and their structural instability during cyclic lithiation/delithiation impairs their electrochemical cycling performance, posing challenges for large-scale applications. This paper explores the application of an Al2O3 coating using an atomic layer deposition (ALD) system on Ni-enriched Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode material. Characterization techniques, including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, were used to assess the impact of alumina coating on the morphology and crystal structure of NCM811. The results confirmed that an ultrathin Al2O3 coating was achieved without altering the microstructure and lattice structure of NCM811. The alumina-coated NCM811 exhibited improved cycling stability and capacity retention in the voltage range of 2.8–4.5 V at a 1 C rate. Specifically, the capacity retention of the modified NCM811 was 5%, 9.11%, and 11.28% higher than the pristine material at operating voltages of 4.3, 4.4, and 4.5 V, respectively. This enhanced performance is attributed to reduced electrode–electrolyte interaction, leading to fewer side reactions and improved structural stability. Thus, NCM811@Al2O3 with this coating process emerges as a highly attractive candidate for high-capacity lithium-ion battery cathode materials. [ABSTRACT FROM AUTHOR]

Although SiO 2 as an anode for lithium-ion batteries has an attractive high theoretical capacity (1965 mAh g−1), violent volume changes and poor electrical conductivity during alloying reaction limit its lithium storage performance. Here, we report a SNTs@NC composite anode loaded on flexible CNTs conducting paper (CP). The conductive network of CP promotes the rapid migration of Li ions and electrons, and the multi-dimensional skeleton formed by CNTs and SNTs@NC is conducive to the steady deposition of Li-ions. The excellent flexibility effectively defuses the impact of internal stress on the pole plate structure, showing a longer service life and better cycling stability compared with the traditional copper foil. The composite anode has the advantages of simple preparation, low cost and little environmental pollution, and as an innovative collector, CP effectively eliminates the influence of the volume effect of the anode on the electrochemical performance. This work may provide a novel way for the commercial development of SiO 2 anode or the preparation of flexible self-supporting electrode. [Display omitted] [ABSTRACT FROM AUTHOR]

High-throughput materials research is strongly required to accelerate the development of safe and high energy-density lithium-ion battery (LIB) applicable to electric vehicle and energy storage system. The artificial intelligence, including machine learning with neural networks such as Boltzmann neural networks and convolutional neural networks (CNN), is a powerful tool to explore next-generation electrode materials and functional additives. In this paper, we develop a prediction model that classifies the major composition (e.g., 333, 523, 622, and 811) and different states (e.g., pristine, pre-cycled, and 100 times cycled) of various Li(Ni, Co, Mn)O2 (NCM) cathodes via CNN trained on scanning electron microscopy (SEM) images. Based on those results, our trained CNN model shows a high accuracy of 99.6% where the number of test set is 3840. In addition, the model can be applied to the case of untrained SEM data of NCM cathodes with functional electrolyte additives. [ABSTRACT FROM AUTHOR]

This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered optimal for PMMA nanofibers in order to maintain the structural stability of covered fibers, which, after ceramic film deposition, leads to a fiber diameter of 0.5–0.6 μm. After a chemical and physical analysis of the stages of obtaining ceramic nanotubes, in all cases, uniform deposition of a ceramic film on PMMA fibers and, finally, a uniform structure of ceramic nanotubes were noted. The technological purpose was to use such nanotubes as ingredients in screen-printing inks for electrochemical sensors, because no study directly targeted the subject of ceramic nanotube applications for printed electronics to date. The printing technology was analyzed in terms of the ink deposition process, printed electrode roughness vs. type of ceramic nanotubes, derived inks, thermal curing of the electrodes and the conductivity of electrodes on different support (rigid and flexible) at different curing temperatures. The experimental inks containing ceramic nanotubes can be considered feasible for printed electronics, because they offer fast curing at low temperatures, reasonable conductivity vs. electrode length, good printability on both ceramic or plastic (flexible) supports and good adhesion to surface after curing. [ABSTRACT FROM AUTHOR]

This paper describes a Ag/AgCl electrochemical electrode for marine electric field measurements, which was prepared by depositing silver chloride on a silver foil substrate using double-pulse electrodeposition. The impact of positive direction peak current density and deposition time on electrode performance in the preparation of Ag/AgCl electrodes through double-pulse electrodeposition was investigated. Scanning electron microscopy and voltammetry have been used to study the properties of the prepared electrodes. This work reveals the correlation between the electrochemical behavior of electrodes and the physical properties of their surfaces, especially specific surface area and porosity. The study verified the characteristics of Ag/AgCl marine electric field electrodes obtained with different pulse parameters by analyzing the potential stability and noise level of the electrode in salt water. The study's results have positive significance for improving the accuracy of marine electric field measurements. [ABSTRACT FROM AUTHOR]

Abstract Transition metal oxides have been considered as a promising class of electrode materials in electrochemical energy storage devices and possess better capacities than mono-metal oxides. For the development of lithium-ion energy storage systems, the architecture of the electrode material plays a vital role. Herein, we have synthesized one-dimensional (1D) mesoporous NiCo 2 O 4 hollow nanofibers (HNFs) with the flaky architecture of its surface using the lab waste filter paper as a template during the hydrothermal process. The NiCo 2 O 4 HNFs show good electrochemical properties such as initial discharge capacity of 1702 mAh g−1 with the coulombic efficiency of 82% at a current density of 100 mA g−1, in comparison to NiCo 2 O 4 nanospheres (NSs) delivering an initial discharge capacity of 1204 mAh g−1 with the coulombic efficiency of 74%. The HNFs with interconnected flaky surface provides a large number of lithium storage sites and also shortens the diffusion path for both the lithium ions and electrons and thereby enhancing the performance of Li-ion batteries. Graphical abstract Image 1 Highlights • Lab waste filter paper used as a template for growing the NiCo 2 O 4 hollow nanofibers. • Template assisted hydrothermal process for synthesis of complex structures. • Electrochemical behaviors of nanofibers and nanospheres morphology is compared. • Hollow nanofibers delivers better cyclic performance as compared to nanospheres. • Synthesis of NiCo 2 O 4 hollow nanofibers as an efficient anode for Li-ion batteries. [ABSTRACT FROM AUTHOR]

This paper discusses the electrochemical properties of thin-film, planar, titanium–platinum (Ti-Pt) microelectrodes fabricated using glass or silicon substrates and compares their performance to the classic platinum (Pt) microelectrodes embedded in glass. To analyze the possible differences coming both from the size of the tested electrodes as well as from the substrate, short- and long-term electrochemical tests were performed on selected water electrolytes (KCl, HCl, KOH). To study the electrochemical response of the electrodes, the cyclic voltammetry (CV) measurements were carried out at different scanning rates (from 5 to 200 mV/s). Long-term tests were also conducted, including one thousand cycles with a 100 mV/s scan rate to investigate the stability of the tested electrodes. Before and after electrochemical measurements, the film morphology was analyzed using a scanning electron microscope (SEM). The good quality of the thin-film Pt electrodes and the high repeatability in electrochemical response have been shown. There are minor differences in standard deviation values taken from electrochemical measurements, comparing thin-film and wire-based electrodes. Damages or any changes on the electrodes' surfaces were revealed by SEM observations after long-term electrochemical tests. [ABSTRACT FROM AUTHOR]

Pholcodine, an anti-tussive medication widely used as an over-the-counter, OTC drug, has recently faced restrictions in several countries. This paper presents a sensitive electrochemical approach for pholcodine detection. The electrochemical method involved fabricating a graphene nanoplatelets electrode, incorporating polythiophene nanospheres polymer to promote electron transfer and increase the activated surface area. Characterization of the fabricated electrode was performed using transmission electron microscopy, ATR-Fourier-transform infrared spectroscopy, X-ray crystallography, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The electrochemical behavior of pholcodine with the fabricated electrode was investigated using cyclic voltammetry, chronoamperometry, square wave voltammetry (SWV), and differential pulse voltammetry (DPV). The developed electrode led to a linear response for pholcodine ranging from 10 to 45 mg/L with detection limits of 1.41 and 1.51 mg/mL for SWV and DPV, respectively and quantification limits of 4.27 and 4.57 mg/L for SWV and DPV, respectively. The proposed method has accurately recovered pholcodine in spiked serum samples with a recovery percentage ranging from 1.2 to 2.9%. The optimized method is found to be accurate, precise, and robust by applying validation parameters provided by International Council for Harmonization. Two green metrics were computed to assess the method's greenness, the findings showed that the developed method is environmentally friendly with minimum sample preparation steps. Article highlights: Fabrication of electrochemical electrode using graphene nanoplatelets modified with polythiophene nanospheres. Voltammetric analysis of pholcodine using square wave voltammetry and differential pulse voltammetry with method validation according to International Council for Harmonization (ICH) guidelines. Assessment of the method's greenness using two green assessment tools; analytical GREEness metric (AGREE) and complementary green analytical procedure index (ComplexGAPI) software tools. [ABSTRACT FROM AUTHOR]

Ni-rich layered cathodes are deemed as a potential candidate for high-energy-density lithium-ion batteries, but their high sensitivity to air during storage and poor thermal stability are a vital challenge for large-scale applications. In this paper, distinguished from the conventional surface modification and ion doping, an effective solid-solution strategy was proposed to strengthen the surface and structural stability of Ni-rich layered cathodes by introducing Li2MnO3. The structural analysis results indicate that the formation of Li2CO3 inert layers on Ni-rich layered cathodes during storage in air is responsible for the increased electrode interfacial impedance, thereby leading to the severe deterioration of electrochemical performance. The introduction of Li2MnO3 can reduce the surface reactivity of Ni-rich cathode materials, playing a certain suppression effect on the formation of surface Li2CO3 layer and the deterioration of electrochemical performances. Additionally, the thermal analysis results show that the heat release of Ni-rich cathodes strongly depends on the charge of states, and Li2MnO3 can suppress oxygen release and significantly enhance the thermal stability of Ni-rich layered cathodes. This work provides a method to improving the storage performance and thermal stability of Ni-rich cathode materials. [ABSTRACT FROM AUTHOR]

Nowadays, lithium-ion batteries are undoubtedly known as the most promising rechargeable batteries. However, these batteries face some big challenges, like not having enough energy and not lasting long enough, that should be addressed. Ternary Ni-rich Li[NixCoyMnz]O2 and Li[NixCoyAlz]O2 cathode materials stand as the ideal candidate for a cathode active material to achieve high capacity and energy density, low manufacturing cost, and high operating voltage. However, capacity gain from Ni enrichment is nullified by the concurrent fast capacity fading because of issues such as gas evolution, microcracks propagation and pulverization, phase transition, electrolyte decomposition, cation mixing, and dissolution of transition metals at high operating voltage, which hinders their commercialization. In order to tackle these problems, researchers conducted many strategies, including elemental doping, surface coating, and particle engineering. This review paper mainly talks about origins of problems and their mechanisms leading to electrochemical performance deterioration for Ni-rich cathode materials and modification approaches to address the problems. [ABSTRACT FROM AUTHOR]

Protein preconcentration is an essential sample preparation step for analysis in which the targeted proteins exist in low concentrations, such as bodily fluids, water, or wastewater. Nonetheless, very few practical implementations of miniaturized protein preconcentration devices have been demonstrated in practice, and even fewer have been integrated with other microanalytical steps. Existing approaches rely heavily on additional chemicals and reagents and introduce complexity to the overall assay. In this paper, we propose a novel miniaturized isoelectric focusing-based protein preconcentration screening device based on electrochemically derived pH gradients rather than existing chemical reagent approaches. In this way, we reduce the need for additional chemical reagents to zero while enabling device incorporation in a seamlessly integrated full protein analysis microsystem via Lab-on-PCB technology. We apply our previously presented Lab-on-PCB approach to quantitatively control the pH of a solution in the vicinity of planar electrodes using electrochemical acid generation through redox-active self-assembled monolayers. The presented device comprises a printed circuit board with an array of gold electrodes that were functionalized with 4-aminothiophenol; this formed a self-assembled monolayer that was electropolymerized to improve its electrochemical reversibility. Protein preconcentration was performed in two configurations. The first was open and needed the use of a holder to suspend a well of fluid above the electrodes; the second used microfluidic channels to enclose small volumes of fluid. Reported here are the resulting data for protein preconcentration in both these forms, with a quantitative concentration factor shown for the open form and qualitative proof shown for the microfluidic. [ABSTRACT FROM AUTHOR]

In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu+2, Cd+2, Pb+2, Zn+2, Ni+2, and Co+2, often present in wastewater, has been carried out. By analyzing the kinetics and fluid dynamics of the process found in literature, a general dimensionless equation, Sh = f(Re), has been determined, describing a general trend for all the analyzed systems regardless of the geometry, dimensions, and starting conditions. Thus, a map in the log(Sh) vs. log(Re) plane has been reported by characterizing the whole ion electrochemical depletion process and highlighting the existence of a good correlation among all the results. Moreover, because in recent years, the interest in using this three-dimensional cathode material seems to have slowed, the intent is to revive it as a useful tool for metal recovery, recycling processes, and water treatments. [ABSTRACT FROM AUTHOR]

Pt-based electrochemical ammonia-nitrogen sensors played a significance role in real-time monitoring the ammonia-nitrogen concentration. The alloying of Pt and transition metals was one of the effective ways to increase the detectability of the sensitive electrode. In this paper, a self-supported electrochemical electrode for the detection of ammonia nitrogen was obtained by the electrodeposition of PtNi alloy nanoleaves on a carbon cloth (PtNi-CC). Experimental results showed that the PtNi-CC electrode exhibited enhanced detection performance with a wide linear range from 0.5 to 500 µM, high sensitivity (7.83 µA µM−1 cm−2 from 0.5 to 150 μM and 0.945 µA µM−1 cm−2 from 150 to 500 μM) and lower detection limit (24 nM). The synergistic effect between Pt and Ni and the smaller lattice spacing of the PtNi alloy were the main reasons for the excellent performance of the electrode. This work showed the great potential of Pt-based alloy electrodes for the detection of ammonia-nitrogen. [ABSTRACT FROM AUTHOR]

All-solid-state lithium-ion batteries (ASSLBs) represent a promising breakthrough in battery technology owing to their high energy density and exceptional stability. When crafting cathode electrodes for ASSLBs, the solid electrolyte/cathode material interface is physically hindered by the specific morphology of carbon additive materials. In this paper, we examine the distribution of conductive additives within the electrode and its impact on the electrochemical performance of composites incorporating either nano-sized carbon black (CB) or micron-sized carbon nanofibers (CNF) into Ni-rich (LiNi0.8Co0.1Mn0.1O2) cathode material based composites. When nano-sized CB is employed as a conductive additive, it enhances the electrical conductivity of the composite by adopting a uniform distribution. However, its positioning between the solid electrolyte and cathode material leads to an increase in interfacial resistance during charge and discharge cycles, resulting in decreased electrochemical performance. In contrast, using micron-sized CNF as a conductive additive results in a reduction in the composite's electrical conductivity compared to CB. Nevertheless, due to the comparatively uninterrupted interfaces between the solid electrolyte and cathode materials, it exhibits superior electrochemical characteristics. Our findings are expected to aid the fabrication of electrochemical-enhanced cathode composite electrodes for ASSLBs. [ABSTRACT FROM AUTHOR]

Hormones regulate several physiological processes in living organisms, and their detection requires accuracy and sensitivity. Recent advances in nanostructured electrodes for the electrochemical detection of hormones are described. Nanostructured electrodes' high surface area, electrocatalytic activity, and sensitivity make them a strong hormone detection platform. This paper covers nanostructured electrode design and production using MOFs, zeolites, carbon nanotubes, metal nanoparticles, and 2D materials such as TMDs, Mxenes, graphene, and conducting polymers onto electrodes surfaces that have been used to confer distinct characteristics for the purpose of electrochemical hormone detection. The use of aptamers for hormone recognition is producing especially promising results, as is the use of carbon-based nanomaterials in composite electrodes. These materials are optimized for hormone detection, allowing trace-level quantification. Various electrochemical techniques such as SWV, CV, DPV, EIS, and amperometry are reviewed in depth for hormone detection, showing the ability for quick, selective, and quantitative evaluation. We also discuss hormone immobilization on nanostructured electrodes to improve detection stability and specificity. We focus on real-time monitoring and tailored healthcare with nanostructured electrode-based hormone detection in clinical diagnostics, wearable devices, and point-of-care testing. These nanostructured electrode-based assays are useful for endocrinology research and hormone-related disease diagnostics due to their sensitivity, selectivity, and repeatability. We conclude with nanotechnology–microfluidics integration and tiny portable hormone-detection devices. Nanostructured electrodes can improve hormone regulation and healthcare by facilitating early disease diagnosis and customized therapy. [ABSTRACT FROM AUTHOR]

Energy storage materials are constantly being improved and developed to cope with the ever-increasing demand of the electronic devices industry. Various synthetic approaches have been used to manufacture electrode materials. This paper is focused on the use of intrinsically conductive polymers such as polypyrrole (PPy) in the development of single-walled carbon nanotube-polyimide, SWCNT-PI, supercapacitor electrode materials. The polypyrrole used in the study is doped with different organic acid dopants of various sizes, including styrene sulfonic acid, SSA, toluene sulfonic acid, TSA, dodecylbenzene sulfonic acid, DBSA, naphthalene disulfonic acid, NDSA, and naphthalene trisulfonic acid, NTSA. The number of sulfonic acid functional group per dopant molecule varied from one to three, while the number of benzene rings in the aromatic unit varied from one to two. It is believed that, as the sulfonic acid to the dopant molecule ratio changes, the morphology and electrochemical properties of the doped PPy-coated electrode material will change accordingly. The change in the morphology of the doped PPy, due to the respective dopant, is correlated with the change in the electrochemical properties of the modified composite electrode. The naphthalene trisulfonic acid (NTSA) dopant was found to produce the highest specific capacitance of about 119 F/g at 5 mV/s. Furthermore, the NTSA-doped PPy electrode system showed the highest porosity and highest tan delta damping peak height for the a-transition. The styrene sulfonic acid-doped PPy/SWCNT-PI electrode material showed an impressive storage modulus of more than 2 GPa, but lower porosity. Styrene polymerization is believed to have occurred. The results obtained indicate that the porosity and electrochemical properties of the electrode materials are correlated. [ABSTRACT FROM AUTHOR]

In this paper, a relationship between the structure and the electrical properties of a nanocrystalline composite ceramics xNa2O·(100 − x)V2O5 with 'x' of 5, 15, 25, 35, and 45 mol%, abbreviated as xNV, was investigated by X-ray diffractometry (XRD), X-ray absorption spectroscopy (XAS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and cathode active performance in Na-ion battery (SIB). For the expected sodium vanadium bronzes (NaxV2O5) precipitation, the preparation of xNV was performed by keeping the system in the molten state at 1200 °C for one hour, followed by a temperature decrease in the electric furnace to room temperature at a cooling rate of 10 °C min−1. XRD patterns of the 15NV ceramic exhibited the formation of Na0.33V2O5 and NaV3O8 crystalline phases. Moreover, the V K-edge XANES showed that the absorption edge energy of ceramics 15NV recorded at 5479 eV is smaller than that of V2O5 at 5481 eV, evidently indicating a partial reduction from V5+ to V4+ due to the precipitation of Na0.33V2O5. In the cyclic voltammetry, reduction peaks of 15NV were observed at 1.12, 1.78 V, and 2.69 V, while the oxidation peak showed up only at 2.36 V. The values of the reduction peaks were related to the NaV3O8 crystalline phase. Moreover, the diffusion coefficient of Na+ (DNa+) gradually decreased from 8.28 × 10−11 cm2 s−1 to 1.23 × 10−12 cm2 s−1 with increasing Na2O content (x) from 5 to 45 mol%. In the evaluation of the active cathode performance of xNV in SIB, ceramics 15NV showed the highest discharge capacity 203 mAh g−1 at a current rate of 50 mA g−1. In the wider voltage range from 0.8 to 3.6 V, the capacity retention was maintained at 50% after 30 cycles, while it was significantly improved to 90% in the narrower voltage range from 1.8 to 4.0 V, although the initial capacity decreased to 56 mAh g−1. It is concluded that the precipitation of the Na0.33V2O5 phase improved the structural and electrical properties of 15NV, which provides a high capacity for the Na-ion battery when incorporated as a cathode active material. [ABSTRACT FROM AUTHOR]

Diabetes remains a great threat to human beings' health and its world prevalence is projected to reach 9.9% by 2045. At present, the detection methods used are often invasive, cumbersome and time-consuming, thus increasing the burden on patients. In this paper, we propose a novel noninvasive and low-cost biosensor capable of detecting glucose in human sweat using enzyme-based electrodes for point-of-care uses. Specifically, an electrochemical method is applied for detection and the electrodes are covered with multilayered films including ferrocene-polyaniline (F-P), multi-walled carbon nanotubes (MWCNTs) and glucose oxidase (GOx) on Cu substrates (GOx/MWCNTs/F-P/Cu). The coated layers enhance the immobilization of GOx, increase the conductivity of the anode and improve the electrochemical properties of the electrode. Compared with the Cu electrode and the F-P/Cu electrode, a maximum peak current is obtained when the MWCNTs/F-P/Cu electrode is applied. We also study its current response by cyclic voltammetry (CV) at different concentrations (0–2.0 mM) of glucose solution. The best current response is obtained at 0.25 V using chronoamperometry. The effective working lifetime of an electrode is up to 8 days. Finally, to demonstrate the capability of the electrode, a portable, miniaturized and integrated detection device based on the GOx/MWCNTs/F-P/Cu electrode is developed. The results exhibit a short response time of 5 s and a correlation coefficient R2 of 0.9847 between the response current of sweat with blood glucose concentration. The LOD is of 0.081 mM and the reproducibility achieved in terms of RSD is 3.55%. The sweat glucose sensor is noninvasive and point-of-care, which shows great development potential in the health examination and monitoring field. [ABSTRACT FROM AUTHOR]

Graphene is extremely sensitive to its surrounding environment. In fact, any modification on its surface, such as an adsorption of a molecule, can change its properties. The conductivity of graphene is a crucial parameter to be examined for potential graphene-based applications, especially biosensors. In this paper, we have investigated the effects of non-covalent functionalization based on π–π interaction, using 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE), on the conductivity of graphene-based electrodes by electrochemical techniques. Graphene layers were obtained by chemical vapor deposition (CVD) and characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). The results demonstrate the synthesis of a high quality and continuous monolayer graphene with an I2D/IG ratio = 2.71 and ID = 0. After the functionalization of graphene-based electrode with PBASE, the electrochemical analyses confirmed a p-doping effect existence influencing the conductivity by increasing the charge transfer resistance Rct from 816.5 to 2213 Ω. Furthermore, increasing the concentration of PBASE from 5 mM to 10 mM did not affect the conductivity as the Rct did not change. Solvent adsorption was found to be the main cause of the decrease in conductivity during the functionalization process. This study highlights the effect of non-covalent π-π stacking of PBASE on graphene to tune the electrical properties of graphene through functionalization processes for a better performance for their use as biosensors. [ABSTRACT FROM AUTHOR]

As one of the most common inorganic ions in daily food and ecological environment, nitrate (NO3−) is potentially harmful to both environment and humans. Therefore, the detection of nitrate concentration is quite important. Chemical sensors, as analytical measurement tools, usually demonstrate high selectivity, fast analysis speed, simple structure, convenient operation, and low cost and are considered to be a promising method for ion identification and detection. In this paper, a miniaturized electrochemical electrode is fabricated based on the microfabrication technology, and an electrochemical sensor for the detection of nitrate concentration in water is developed by combining the deposition technology of nanometal particles with electrochemical analysis technique. The developed electrochemical sensor utilizes electrochemical deposition to prepare a copper (Cu) granular sensitive film with a branch-cluster structure on the surface of a circular working electrode (Pt). Using copper's characteristics of electrocatalytic reduction of NO3− in the acid solution environment (pH = 2), the concentration of NO3− in the water sample was calculated by measuring the reduction current on the working electrode when the electrocatalytic reduction reaction of NO3− occurred on the surface of the copper-sensitive membrane. The sensitive film is characterized and detected both with the scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) technique; and the microsensor is used to detect nitrate standard samples; a high detection sensitivity (24.9 μA/mmol·L−1) is achieved in the concentration range of 0.0 to 3.0 mmol/L. At the same time, a MEMS three-electrode sensor without gold wire bonding and insulating glue packaging is designed, and an automatic detection system is constructed with a STM32f103 microcontroller as the controller to realize the automated detecting process for nitrate ions. At the same time, a distributed system is constructed, which can describe the nitrate concentration in every position of the water area and realize the monitoring of the whole water area. The detection system can meet the working environment under most conditions and has practical significance. [ABSTRACT FROM AUTHOR]

Foamed metal materials are introduced as a novel tool to manufacture cathodes for the electrochemical machining (ECM) of involute internal spline made from difficult-to-cut materials. This paper analyzes the porosity density and electrolyte flow characteristics of foamed metal cathodes. The geometric and mathematical model of the involute internal spline by ECM is built, and electric field simulations are conducted by using the COMSOL Multiphysics software to determine the ECM results. Based on the simulation results, suitable initial process parameters are obtained and relative process experiments are carried out. The experiment results demonstrate that foamed metal material can be used to fabricate tool cathodes for ECM of involute internal spline. When the machining voltage is 10 V, the electrolyte type is 2% NaCl + 8% NaNO3 solution, and cathodic feed rate is 1.00 mm/min, the involute internal spline machined by axial ECM can achieve better profiles that meet the finishing accuracy and precision requirements. The experimental application of foamed metal cathode lays a new technical foundation for ECM to manufacture complex internal structures and from design theory to contemporary industrial praxis. [ABSTRACT FROM AUTHOR]

In this paper, [Ni0.9Co0.1](OH)2 precursor is used to dope H3BO3 to synthesize positive electrode material when mixing lithium in wet method, and to explore the best doping by testing the microscopic morphology and electrochemical performance of the positive electrode material amount and calcination temperature. After doping with B, the microstructure of the material is improved, and the primary crystal grains are oriented and agglomerated into a needle shape. This good crystal structure can slow down the generation of grain microcracks and mechanical fracture, and improve the cycle stability of the positive electrode material. After doping B, the discharge specific capacity was slightly improved. When the calcination temperature is 750 °C and the doping amount of B is 1.0 mol%, the first discharge specific capacity reaches 223 mAh g−1. More importantly, the capacity retention rate of the battery after 100 cycles has been greatly improved, from 74 % without doping B to 87 %. [ABSTRACT FROM AUTHOR]

Understanding the electrochemical and mechanical degradations inside the electrodes of lithium-ion battery is crucial for the design of robust electrodes. A typical lithium-ion battery electrode consists of active particles enclosed with conductive binder and an electrolyte. During the charging and discharging process, these adjacent materials create a mechanical confinement which suppresses the expansion and contraction of the particles and affects overall performance. The electrochemical and mechanical response mutually affect each other. The particle level expansion/contraction alters the electrochemical response at the electrode level. In return, the electrode level kinetics affect the stress at the particle level. In this paper, we developed a multiphysics–multiscale model to analyze the electrochemical and mechanical responses at both the particle and cell level. The 1D Li-ion battery model is fully coupled with 2D representative volume element (RVE) model, where the particles are covered in binder layers and bridged through the binder. The simulation results show that when the binder constraint is incorporated, the particles achieve a lower surface state of charge during charging. Further, the cell charging time increases by 7.4% and the discharge capacity reduces by 1.4% for 1 C-rate charge/discharge. In addition, mechanical interaction creates inhomogeneous stress inside the particle, which results in particle fracture and particle–binder debonding. The developed model will provide insights into the mechanisms of battery degradation for improving the performance of Li-ion batteries. [ABSTRACT FROM AUTHOR]

In this work, β-FeOOH was synthesized and grown on carbon paper with the assistance of dopamine (PDA) via a facile hydrothermal method, producing β-FeOOH self-supporting electrode eventually. Electrochemical anodic oxidation performance to methyl orange (MO) solution using β-FeOOH anode was investigated and the major influencing factors such as current density, initial pH value and initial MO concentration on MO degradation efficiency were further explored. Experimental results suggested that 99.4% degradation rate of MO could be achieved only after 25 min electrolysis, its pseudo first-order reaction kinetic constant was 11.3 ⅹ 10−2 min−1 and the COD removal ratio was 37.3% after 120 min electrolysis under optimized conditions: current density was 10 mA cm−2, initial pH value was 3 and initial MO concentration was 10 mg L−1. At the same time, β-FeOOH electrode also exhibited a high cycling stability and the MO removal ratio was still keeping at 84.9% after eight cycles. Moreover, this electrode showed efficient decomposition performance to multiple simulated pollutants, indicating the well potential practical application values of β-FeOOH electrode. At last, the proposed degradation mechanism of MO was evaluated according to the analyzing results of UV–vis and HPLC-MS to MO solution under different degradation durations. • β-FeOOH self-supporting electrode was prepared via a facile hydrothermal method. • 99.4% removal ratio of MO could be achieved only after 25 min electrolysis. • Operating conditions during electrochemical degradation process were optimized. • The degradation intermediates of MO were identified and pathways were proposed. [ABSTRACT FROM AUTHOR]

In order to develop sustainable and renewable energy sources, novel approaches to design noble metal-free efficient electrocatalysts such as carbon and metal dichalcogenides nanostructures are being investigated for hydrogen evolution reaction (HER). In the present work, we successfully synthesize iron nanoparticles (Fe–GT) via facile green approach without using any surfactant and for the first time, green-synthesized iron nanoparticles are utilized as catalysts for production of multiwalled carbon nanotubes (MWCNTs). The synthesized MWCNTs (GT) were characterized using SEM, TEM, XRD and Raman spectroscopy techniques. The MWCNTs (GT)-coated conducting carbon paper electrode was applied as non-precious metal electrocatalyst for HER. The MWCNTs (GT) electrode demonstrates improved electrochemical activity towards HER with a smaller value of Tafel slope ~ 105 mV dec− 1 and overpotential (η10) ~ 192 mV, which is quite comparable to other reported metal-free HER catalyst. We also designed an indigenous electrochemical cell and showed the hydrogen production and collection using MWCNTs (GT) as cathode. [ABSTRACT FROM AUTHOR]

[Display omitted] • PO 4 3−-doping and Li 3 PO 4 -coating of dual modification of LiNiO 2 are achieved. • PO 4 3− doping improves the reversibility of crystal structure. • PO 4 3− doping induces surface structural transformation of the material. • Li 3 PO 4 coating could ameliorate the interface stability. Lithium nickel oxide (LiNiO 2) cathode materials are featured with high capacity and low cost for rechargeable lithium-ion batteries but suffer from severe structure and interface instability. Bulk doping together with surface coating has been proven to be an efficient approach to improve the inner structure and interfacial stability of the LiNiO 2 cathode material. Nevertheless, the role of anion doping seems to be quite different from that of cation doping, and a deep insight will be desirable for the structure design of the LiNiO 2 cathode material. In this paper, PO 4 3−-doped and Li 3 PO 4 -coating of dual modification of LiNiO 2 are achieved via a facile approach. It is demonstrated that the PO 4 3− anions are doped into the tetrahedron vacant sites of the crystal structure, alleviating the phase transition and improving the reversibility of crystal structure. Besides, the Li 3 PO 4 coating layer ameliorates the interface stability to restrain the side reactions. Therefore, the dual modification enhances overall structural stability of the material to provide excellent performance. Moreover, the consumption of the Li residues by the formation of Li 3 PO 4 coating layer, and the enlarged interlayer spacing of the crystal structure by PO 4 3− doping can facilitate the Li+ ions diffusion, resulting in a superior rate capability. [ABSTRACT FROM AUTHOR]

The manufacturing of surface microstructure is an important means for the modification of surface characteristics of parts. Through-mask electrochemical manufacturing is also an efficient way to fabricate surface microstructures. Nevertheless, in cases where the through-mask electrochemical manufacturing is used for the fabrication of microstructures, many experiments are required to control the cross-section morphology of the microstructures. Furthermore, there is a lack of quantitative analysis of the impact of key variables on the process. In this paper, using numerical simulations based on the mask geometry, we analyze the effects of the aspect ratio of mask feature and the gap between cathode to mask on electrochemical micromachining. We further investigate the influence laws of the mask geometry on the anode current density distribution and forming process. A critical value of "0.8" is also determined for aspect ratio of mask feature which is closely related to the anode current density distribution and forming process. The through-mask electrochemical micromachining experiments confirm the effect laws of the geometric structure of the mask feature. And the critical value (0.8) of aspect ratio can be used as the basis for selecting mask feature. [ABSTRACT FROM AUTHOR]

Conventional refractory materials used for calcining ternary lithium‐ion battery cathode materials, such as mullite, cordierite, and magnesia‐alumina spinel, are vulnerable to attack by Li(NixCoyMn1−x−y)O2 (LNCM) materials and therefore have a short service life. In order to improve the corrosion resistance of refractory materials to LNCM materials, mullite‐Al2TiO5 materials with different contents were synthesized in this paper by using calcined mullite powder, TiO2 powder, and La2O3 powder as raw materials, which were calcined at 1500–1600°C temperature, respectively. In this study, the potential of the materials for the preparation of LNCM materials was investigated in terms of its physical properties, resistance to the corrosion of LNCM materials, and resistance to thermal shock. The results showed that mullite‐Al2TiO5 composites can be successfully synthesized at 1500–1600°C, and the physical properties of the materials met the production requirements. The prepared mullite‐Al2TiO5 composites also exhibited better physical properties, good corrosion resistance, and proper thermal shock resistance compared with mullite refractories. [ABSTRACT FROM AUTHOR]

This paper focuses on the evaluation of the mobility of four hexachlorocyclohexane (HCH) isomers by soil vapor extraction (SVE) coupled with direct electrokinetic (EK) treatment without adding flushing fluids. SVE was found to be very efficient and remove nearly 70 % of the four HCH in the 15‐days of the tests. The application of electrokinetics produced the transport of HCH to the cathode by different electrochemical processes, which were satisfactorily modelled with a 1‐D transport equation. The increase in the electric field led to an increase in the transport of pollutants, although 15 days was found to be a very short time for an efficient transportation of the pollutants to the nearness of the cathode. Loss of water content in the vicinity of the cathode warns about the necessity of using electrokinetic flushing technologies instead of simple direct electrokinetics. Thus, results point out that direct electrokinetic treatment without adding flushing fluids produced low current intensities and ohmic heating that contributes negatively to the performance of the SVE process. No relevant differences were found among the removal of the four isomers, neither in SVE nor in EK processes. [ABSTRACT FROM AUTHOR]

Since there exist discharge problems in gas insulated metal-enclosed switchgear due to internal metal particle movement, the study in this paper thus, conducted an experiment and simulation research on the movement characteristics of particles, where the charge on particle and the collision recovery coefficient (CRC) was obtained. When the electrode is brass, the charge on the particle is close to the theory one and the CRC of aluminum, stainless steel and particle are 0.52, 0.75 and 0.79 respectively. Accordingly, the study, in order to take the particle charge and its collision process into consideration, established a particle movement model, and conducted a test has thereof. The results show that there exists excellent consistency between charge and its collision. According to the research, the relationship between particle size, material and collision characteristics was revealed. The result shows that under DC voltage the metal particle collision frequency decreases with the increase of particle size when the material of the particles is the same. The time difference between particles' moving to high voltage electrode and ground electrode becomes greater with the increase of the size of the particle. When the particle material is different, the collision characteristics are influenced by its density and collision recovery coefficient of restitution. Particle motion velocity loss becomes less before and after the collision when its collision recovery coefficient of restitution is larger. So the collision frequency is higher. The research results in this paper can offer some reference value to particles suppression measures in gas insulated metal-enclosed transmission line. [ABSTRACT FROM PUBLISHER]