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Water desalination technology has emerged as a critical area of research, particularly with the advent of more cost-effective alternatives to conventional methods, such as reverse osmosis and thermal evaporation. Given the vital importance of water for life and the scarcity of potable water for agriculture and livestock—especially in the Kingdom of Saudi Arabia—the capacitive deionization (CDI) method for removing salt from water has been highlighted as the most economical choice compared to other techniques. CDI applies a voltage difference across two porous electrodes to extract salt ions from saline water. This study will investigate water desalination using CDI, utilizing a compact DC power source under 5 volts and a standard current of 2 amperes. We will convert waste materials like sunflower seeds, peanut shells, and rice husks into activated carbon through carbonization and chemical activation to improve its pore structure. Critical parameters for desalination, including voltage, flow rate, and total dissolved solids (TDS) concentration, have been established. The initial TDS levels are set at 2000, 1500, 1000, and 500 ppm, with flow rates of 38.2, 16.8, and 9.5 mL/min across the different voltage settings of 2.5, 2, and 1.5 volts, applicable to both direct and inverse desalination methods. The efficiency at TDS concentrations of 2000, 1500, and 1000 ppm remains between 18% and 20% for up to 8 min. Our results indicate that the desalination process operates effectively at a TDS level of 750 ppm, achieving a maximum efficiency of 45% at a flow rate of 9.5 mL/min. At voltages of 2.5 V, 2 V, and 1.5 V, efficiencies at 3 min are attained with a constant flow rate of 9.5 mL/min and a TDS of 500 ppm, with the maximum desalination efficiency reaching 56%.

Carbon fiber is known for being lightweight and adaptable, making it useful for various current and future applications. However, to broaden the use of carbon fibers beyond niche applications, production costs must be lowered. A potential approach to achieving this is by using more affordable raw materials, such as lignin, which is renewable, cost-effective, and widely available compared with the materials commonly used in industry today. This study explores the impact of metal ions on the quality of carbon fiber derived from lignin, focusing on its mechanical and electrochemical properties and morphology. The effect of a specific metal ion (Ni(NO3)2·6H2O) was examined by incorporating it into the spinning solution. The carbonization stage of the fiber was conducted at temperatures of 800, 900, and 1000 °C in an inert atmosphere. Scanning electron microscopy (SEM) analysis showed no defects or damage in any of the fibers. Therefore, it was concluded that moderate concentrations of Ni2+ ions in the fibers do not influence the stabilization or carbonization processes, thus leaving the mechanical properties of the final carbon fiber unchanged. These carbon nanofibers were also tested as a sustainable alternative to the non-renewable materials used in electrodes for energy storage and conversion devices, such as supercapacitors. Electrochemical performance was assessed in a 6 M KOH solution using a two-electrode cell configuration. Galvanostatic charge–discharge tests were performed at different current densities (0.1, 0.25, 0.5, 1.0, and 2.0 A g−1). The specific capacitance of the carbon nanofibers was determined from CVA data at various scan rates: 5, 10, 20, 40, 80, and 160 mV s−1. The results indicated that at 0.1 A g−1, the capacitance reached 108 F g−1, and at a scan rate of 5 mV s−1, it was 91 F g−1. The innovation of this work lies in its use of lignin, a renewable and widely available material, to produce carbon fibers, reducing costs compared with traditional methods. Additionally, the incorporation of nickel ions enhances the electrochemical properties of the fibers for supercapacitor applications without compromising their mechanical performance.

In this study, xCaO‧5Fe2O3‧(95−x)Pb glasses and vitroceramics containing various concentrations of calcium ions (from 0 to 50 mol% CaO) were prepared using the spent anodic plate of a car battery. X-ray diffraction analysis revealed changes in the network structure as a function of CaO content. The intensities of the IR bands due to the sulfate and sulfite units were lowered, indicating a decrease in the sulfurization degree within the lead network. In the UV–vis spectra, the presence of electronic transitions of the Fe3+, Pb2+, and Fe2+ ions were identified. The EPR spectra were characterized by resonance signals centered at about g ~ 2 and 4.3, corresponding to the trivalent iron ions. For the samples with 5 ≤ x ≤ 12, the signals decreased abruptly, suggesting a Fe3+→Fe2+ interconversion and the formation of the Fe3O4 crystalline phase. A considerable increase in the intensity of the signal centered around g ~ 2 was observed as the CaO concentration increased to 30% in the host matrix. Our results confirm that the higher CaO levels of 3 mol% are responsible for the increase in the radius of curvature of the semicircle arcs in the EIS plots and the decrease in their conductivity.

The brain–computer interface (BCI) is one of the most powerful tools in neuroscience and generally includes a recording system, a processor system, and a stimulation system. Optogenetics has the advantages of bidirectional regulation, high spatiotemporal resolution, and cell-specific regulation, which expands the application scenarios of BCIs. In recent years, optogenetic BCIs have become widely used in the lab with the development of materials and software. The systems were designed to be more integrated, lightweight, biocompatible, and power efficient, as were the wireless transmission and chip-level embedded BCIs. The software is also constantly improving, with better real-time performance and accuracy and lower power consumption. On the other hand, as a cutting-edge technology spanning multidisciplinary fields including molecular biology, neuroscience, material engineering, and information processing, optogenetic BCIs have great application potential in neural decoding, enhancing brain function, and treating neural diseases. Here, we review the development and application of optogenetic BCIs. In the future, combined with other functional imaging techniques such as near-infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI), optogenetic BCIs can modulate the function of specific circuits, facilitate neurological rehabilitation, assist perception, establish a brain-to-brain interface, and be applied in wider application scenarios.

Microbial electrochemical systems that integrate the advantages of inorganic electrocatalysis and microbial catalysis are expected to provide sustainable solutions to the increasing energy shortages, resource depletion, and climate degradation. However, sluggish extracellular electron transfer (EET) at the interface between electroactive microorganisms and inorganic electrode materials is a critical bottleneck that limits the performance of systems. Electrocatalytic nanomaterials are highly competitive in overcoming this obstacle due to their effective association with microbial catalysis. Therefore, this review focuses on the cutting-edge applications and enhancement mechanisms of nanomaterials with electrocatalytic activity in promoting microbial EET. First, the EET mechanism of microbial electrocatalysis in both microbial anodes and cathodes is briefly introduced, and then recent applications of various electrocatalytic nanomaterials in diverse microbial electrochemical systems are summarized, including heteroatom-doped carbons and precious metal, as well as transition metal oxides, sulfides, carbides, and nitrides. The synergistic effects of nanomaterial electrocatalysis and microbial catalysis on enhancing interfacial EET are analyzed. Finally, the challenges and perspectives of realizing high-performance microbial electrochemical systems are also discussed in order to offer some reference for further research.

Electroactive microfiber-based scaffolds aid neural tissue repair. Carbon microfibers (CMFs) coated with the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly[(4-styrenesulfonic acid)-co-(maleic acid)] (PEDOT:PSS-co-MA) provide efficient support and guidance to regrowing axons across spinal cord lesions in rodents and pigs. We investigated the electrical and structural performance of PEDOT:PSS-co-MA-coated carbon MFs (PCMFs) for long-term, biphasic electrical stimulation (ES). Chronopotentiometry and electrochemical impedance spectroscopy (EIS) allowed the characterization of charge transfer in PCMFs during ES in vitro, and morphological changes were assessed by scanning electron microscopy (SEM). PCMFs that were 4 mm long withstood two-million-biphasic pulses without reaching cytotoxic voltages, with a 6 mm length producing optimal results. Although EIS and SEM unveiled some polymer deterioration in the 6 mm PCMFs, no significant changes in voltage excursions appeared. For the preliminary testing of the electrical performance of PCMFs in vivo, we used 12 mm long, 20-microfiber assemblies interconnected by metallic microwires. PCMFs-assemblies were implanted in two spinal cord-injured pigs and submitted to ES for 10 days. A cobalt–alloy interconnected assembly showed safe voltages for about 1.5 million-pulses and was electrically functional at 1-month post-implantation, suggesting its suitability for sub-chronic ES, as likely required for spinal cord repair. However, improving polymer adhesion to the carbon substrate is still needed to use PCMFs for prolonged ES.

Traumatic peripheral nerve injuries (PNI), present with symptoms ranging from pain to loss of motor and sensory function. Difficulties in intraoperative visual assessment of nerve functional status necessitate intraoperative nerve conduction studies (INCSs) by neurosurgeons and neurologists to determine the presence of functioning axons in the zone of a PNI. This process, also referred to as nerve “inching”, uses a set of stimulating and recording electrode hooks to lift the injured nerve from the surrounding surgical field and to determine whether an electrical stimulus can travel through the zone of injury. However, confounding electrical signal artifacts can arise from the current workflow and electrode design, particularly from the mandatory lifting of the nerve, complicating the definitive assessment of nerve function and neurosurgical treatment decision-making. The objective of this study is to describe the design process and verification testing of our group’s newly designed stimulating and recording electrodes that do not require the lifting or displacement of the injured nerve during INCSs. Ergonomic in vivo analysis of the device within a porcine model demonstrated successful intraoperative manipulation of the device, while quantitative nerve action potential (NAP) signal analysis with an ex vivo simulated “inching” procedure on healthy non-human primate nerve tissue demonstrated excellent reproducible recorded NAP fidelity and the absence of NAP signal artifacts at all points of recording. Lastly, electrode pullout force testing determined maximum forces of 0.43 N, 1.57 N, and 3.61 N required to remove the device from 2 mm, 5 mm, and 1 cm nerve models, respectively, which are well within established thresholds for nerve safety. These results suggest that these new electrodes can safely and successfully perform accurate PNI assessment without the presence of artifacts, with the potential to improve the INCS standard of care while remaining compatible with currently used neurosurgical technology, infrastructure, and clinical workflows.

Carbon nanomaterials-based electric double-layer capacitors (EDLCs) are reliable and appealing energy-storage systems offering high power density and long cycling stability. However, these energy storage devices are plagued with critical shortcomings, such as low specific capacitance, inefficient physical/chemical activation process, and self-discharge of electrode materials, hindering their future application. In this work, we use a self-activation process, an environmentally benign and low-cost process, to produce high-performance activated carbon (AC). Novel activated carbon from pecan shells (PS) was successfully synthesized through a single-step self-activation process, which combines the carbonization and activation processes. The as-synthesized pecan shell-derived activated carbon (PSAC) provides a high-porosity, low-resistance, and ordered pore structure with a specific pore volume of 0.744 cm3/g and BET surface area of 1554 m2/g. The supercapacitors fabricated from PSAC demonstrate a specific capacitance of 269 F/g at 2 A/g, excellent cycling stability over 15,000 cycles, and energy and power density of 37.4 Wh/kg and of 2.1 kW/kg, respectively. It is believed that the high-efficiency PSAC synthesized from the novel self-activation method could provide a practical route to environmentally friendly and easily scalable supercapacitors.

The galvanic dissolved oxygen sensor finds widespread applications in multiple critical fields due to its high precision and excellent stability. As its core sensing components, the oxygen-permeable membrane, electrode, and electrolyte significantly impact the sensor’s performance. To systematically investigate the comprehensive effects of these core sensing components on the performance of galvanic dissolved oxygen sensors, this study selected six types of oxygen-permeable membranes made from two materials (Perfluoroalkoxy Polymer (PFA) and Fluorinated Ethylene Propylene Copolymer (FEP)) with three thicknesses (0.015 mm, 0.03 mm, and 0.05 mm). Additionally, five concentrations of KCl electrolyte were configured, and four different proportions of lead–tin alloy electrodes were chosen. Single-factor and crossover experiments were conducted using the OxyGuard dissolved oxygen sensor as the experimental platform. The experimental results indicate that under the same membrane thickness conditions, PFA membranes provide a higher output voltage compared to FEP membranes. Moreover, the oxygen permeability of FEP membranes is more significantly affected by temperature. Furthermore, the oxygen permeability of the membrane is inversely proportional to its thickness; the thinner the membrane, the better the oxygen permeability, resulting in a corresponding increase in sensor output voltage. When the membrane thickness is reduced from 0.05 mm to 0.015 mm, the sensor output voltage for PFA and FEP membranes increases by 86% and 74.91%, respectively. However, this study also observed that excessively thin membranes might compromise measurement accuracy. In a saturated, dissolved oxygen environment, the sensor output voltage corresponding to the six oxygen-permeable membranes used in the experiment exhibits a highly linear inverse relationship with temperature (correlation coefficient ≥ 98%). Meanwhile, the lead–tin ratio of the electrode and electrolyte concentration have a relatively minor impact on the sensor output voltage, demonstrating good stability at different temperatures (coefficient of variation ≤ 0.78%). In terms of response time, it is directly proportional to the thickness of the oxygen-permeable membrane, especially for PFA membranes. When the thickness increases from 0.015 mm to 0.05 mm, the response time extends by up to 2033.33%. In contrast, the electrode material and electrolyte concentration have a less significant effect on response time. To further validate the practical value of the experimental results, the best-performing combination of core sensing components from the experiments was selected to construct a new dissolved oxygen sensor. A performance comparison test was conducted between this new sensor and the OxyGuard dissolved oxygen sensor. The results showed that both sensors had the same response time (49 s). However, in an anaerobic environment, the OxyGuard sensor demonstrated slightly higher accuracy by 2.44%. This study not only provides a deep analysis of the combined effects of oxygen-permeable membranes, electrodes, and electrolytes on the performance of galvanic dissolved oxygen sensors but also offers scientific evidence and practical guidance for optimizing sensor design.

Polyaniline has been utilized in various applications, yet its widespread adoption has often been impeded by challenges. Composite systems have been proposed as a means of mitigating some of these limitations, and anthranilic acid (2-aminobenzoic acid) has emerged as a possible moderator for use in co-polymer systems. It offers improved solubility and retention of electroactivity in neutral and alkaline media, and, significantly, it can also bestow chemical functionality through its carboxylic acid substituent, which can greatly ease post-polymer modification. The benefits of using anthranilic acid (as a homopolymer or copolymer) have been demonstrated in applications including corrosion protection, memory devices, photovoltaics, and biosensors. Moreover, this polymer has been used as a versatile framework for the sequestration of metal ions for water treatment, and, critically, these same mechanisms serve as a facile route for the production of catalytic metallic nanoparticles. However, the widespread adoption of polyanthranilic acid has been limited, and the aim of the present narrative review is to revisit the early promise of anthranilic acid and assess its potential future use within modern smart materials. A critical evaluation of its properties is presented, and its versatility as both a monomer and a polymer across a spectrum of applications is highlighted.

A reference electrode is a half-cell (an electrode) with a stable, well-defined and highly reproducible electrode potential. A vast number of electrodes have been developed for different applications. They are briefly presented. For the common types, the advantages and drawbacks are discussed. Practical hints for daily use are provided.

Ionic liquid modification for carbon-supported platinum (Pt/C) electrocatalysts to enhance their oxygen reduction reaction (ORR) activity has been well recognized. However, the research has only been reported on the low-Pt-loading Pt/C electrocatalysts, e.g., 20 wt%, while in practical applications, usually high-Pt-loading Pt/C electrocatalysts of 45–60 wt% are used. In this work, ionic liquid modification is systematically investigated for a Pt/C electrocatalyst with 60 wt% Pt loading for its ORR activity in the cathode in proton exchange membrane fuel cells (PEMFCs). Various adsorption amounts are studied on the catalyst surface. Different modification behavior is found. Mechanism exploration shows that the adsorption of ionic liquid mainly happens on the Pt electrocatalyst surface and in the micropores of the carbon support. The highest fuel cell power performance is achieved at an ionic liquid loading of 7 wt%, which is much higher than the 3 wt% reported for the low-Pt-loading Pt/C.

The nonlinear characteristics of avalanche photodiodes (APDs) inhibit their performance in high-speed communication systems, thereby limiting their widespread application as optical detectors. Existing theoretical models have not fully elucidated complex phenomena encountered in actual device structures. In this study, actual APD structures exhibiting lower linearity than their ideal counterparts were revealed. Simulation analysis and physical inference based on GaN APDs reveal that electrode size is a noteworthy factor influencing response linearity. This discovery expands the nonlinear theory of APDs, suggesting that APD linearity can be enhanced by suppressing the electrode size effect. A physical model was developed to explain this phenomenon, which is attributed to charge accumulation at the edge of the contact layer. Therefore, we proposed an improved APD design that incorporates an additional gap layer and a buffer layer to stabilize the internal gain under high-current-density conditions, thereby enhancing linearity. Our improved APD design increases the linear threshold for optical input power by 4.46 times. This study not only refines the theoretical model for APD linearity but also opens new pathways for improving the linearity of high-speed optoelectronic detectors.

The study of plant electrophysiology offers promising techniques to track plant health and stress in vivo for both agricultural and environmental monitoring applications. Use of superficial electrodes on the plant body to record surface potentials may provide new phenotyping insights. Bacterial nanocellulose (BNC) is a flexible, optically translucent, and water-vapor-permeable material with low manufacturing costs, making it an ideal substrate for non-invasive and non-destructive plant electrodes. This work presents BNC electrodes with screen-printed carbon (graphite) ink-based conductive traces and pads. It investigates the potential of these electrodes for plant surface electrophysiology measurements in comparison to commercially available standard wet gel and needle electrodes. The electrochemically active surface area and impedance of the BNC electrodes varied based on the annealing temperature and time over the ranges of 50 °C to 90 °C and 5 to 60 min, respectively. The water vapor transfer rate and optical transmittance of the BNC substrate were measured to estimate the level of occlusion caused by these surface electrodes on the plant tissue. The total reduction in chlorophyll content under the electrodes was measured after the electrodes were placed on maize leaves for up to 300 h, showing that the BNC caused only a 16% reduction. Maize leaf transpiration was reduced by only 20% under the BNC electrodes after 72 h compared to a 60% reduction under wet gel electrodes in 48 h. On three different model plants, BNC–carbon ink surface electrodes and standard invasive needle electrodes were shown to have a comparable signal quality, with a correlation coefficient of >0.9, when measuring surface biopotentials induced by acute environmental stressors. These are strong indications of the superior performance of the BNC substrate with screen-printed graphite ink as an electrode material for plant surface biopotential recordings.

In Li-ion batteries, ion diffusion kinetics represent a limitation to combine high capacity and a fast charging rate. To bypass this, textured electrodes have been demonstrated to increase the active surface, decrease the material tortuosity and accelerate the electrolyte wetting. Amongst the structuring technologies, ultrashort pulse laser processing may represent the key option enabling, at the same time, high precision, negligible material deterioration and high throughput. Here, we report a study on the structuring of electrodes with both holes and grooves reaching the metallic collector. Electrochemical models emphasize the importance of hole and line dimensions for the performances of the cell. We demonstrate that we can control the hole and line width by adjusting the applied fluence and the repetition rate. In addition, results show that it is possible to drill 65 µm-deep and ~15 µm-wide holes in nearly 100 µs resulting in up to 10,000 holes/s. To further reduce the takt time, bursts of 40 MHz pulses were also investigated. We show that bursts can reduce the takt time by a factor that increases with the average power and the burst length. Moreover, at comparable fluence, we show that bursts can shorten the process more than theoretically expected.

The Amperometric Gas Sensor (AGS) uses an electrode as the transducer element which converts its signal into a current from the electrochemical reaction of analytes taking place at the electrode surface. Many attempts to improve AGS performance, such as modifying the working electrode, applying a particular gas-permeable membrane, and selecting the proper electrolyte, etc., have been reported in the scientific literature. On the other hand, in the materials community, atomic gold has gained much attention because its physicochemical properties dramatically differ from those of gold nanoparticles. This paper provides an overview of the use of atomic gold in AGSs, both in a bulky AGS and a miniaturized AGS. In the miniaturized AGS, the system must be redesigned; for example, the aqueous electrolyte commonly used in a bulky AGS cannot be used due to volatility and fluidity issues. A Room Temperature Ionic Liquid (RTIL) can be used to replace the aqueous electrolyte since it has negligible vapor pressure; thus, a thin film of RTIL can be realized in a miniaturized AGS. In this paper, we also explain the possibility of using RTIL for a miniaturized AGS by incorporating a quartz crystal microbalance sensor. Several RTILs coated onto modified electrodes used for isomeric gas measurement are presented. Based on the results, the bulky and miniaturized AGS with atomic gold exhibited a higher sensor response than the AGS without atomic gold.

To date, batteries are the most widely used energy storage devices, fulfilling the requirements of different industrial and consumer applications. However, the efficient use of renewable energy sources and the emergence of wearable electronics has created the need for new requirements such as high-speed energy delivery, faster charge–discharge speeds, longer lifetimes, and reusability. This leads to the need for supercapacitors, which can be a good complement to batteries. However, one of their drawbacks is their lower energy storage capability, which has triggered worldwide research efforts to increase their energy density. With the introduction of novel nanostructured materials, hierarchical pore structures, hybrid devices combining these materials, and unconventional electrolytes, significant developments have been reported in the literature. This paper reviews the short history of the evolution of supercapacitors and the fundamental aspects of supercapacitors, positioning them among other energy-storage systems. The main electrochemical measurement methods used to characterize their energy storage features are discussed with a focus on their specific characteristics and limitations. High importance is given to the integral components of the supercapacitor cell, particularly to the electrode materials and the different types of electrolytes that determine the performance of the supercapacitor device (e.g., storage capability, power output, cycling stability). Current directions in the development of electrode materials, including carbonaceous forms, transition metal-based compounds, conducting polymers, and novel materials are discussed. The synergy between the electrode material and the current collector is a key factor, as well as the fine-tuning of the electrode material and electrolyte.

CubeSats have emerged as cost-effective platforms for biological research in low Earth orbit (LEO). However, they have traditionally been limited to optical absorbance sensors for studying microbial growth. This work has made improvements to the sensing capabilities of these small satellites by incorporating electrochemical ion-selective pH and pNa sensors with optical absorbance sensors to enrich biological experimentation and greatly expand the capabilities of these payloads. We have designed, built, and tested a multi-modal multi-array electrochemical-optical sensor module and its ancillary systems, including a fluidic card and an on-board payload computer with custom firmware. Laboratory tests showed that the module could endure high flow rates (1 mL/min) without leakage, and the 27-well, 81-electrode sensor card accurately detected pH (71.0 mV/pH), sodium ion concentration (75.2 mV/pNa), and absorbance (0.067 AU), with the sensors demonstrating precise linear responses (R2 ≈ 0.99) in various test solutions. The successful development and integration of this technology conclude that CubeSat bio-payloads are now poised for more complex and detailed investigations of biological phenomena in space, marking a significant enhancement of small-satellite research capabilities.

The utilization of renewable energy for hydrogen production presents a promising pathway towards achieving carbon neutrality in energy consumption. Water electrolysis, utilizing pure water, has proven to be a robust technology for clean hydrogen production. Recently, seawater electrolysis has emerged as an attractive alternative due to the limitations of deep-sea regions imposed by the transmission capacity of long-distance undersea cables. However, seawater electrolysis faces several challenges, including the slow kinetics of the oxygen evolution reaction (OER), the competing chlorine evolution reaction (CER) processes, electrode degradation caused by chloride ions, and the formation of precipitates on the cathode. The electrode and catalyst materials are corroded by the Cl− under long-term operations. Numerous efforts have been made to address these issues arising from impurities in the seawater. This review focuses on recent progress in developing high-performance electrodes and electrolyser designs for efficient seawater electrolysis. Its aim is to provide a systematic and insightful introduction and discussion on seawater electrolysers and electrodes with the hope of promoting the utilization of offshore renewable energy sources through seawater electrolysis.

Voltammetry has been used in many industries and has been a popular method for food analysis in recent years. Its high sensitivity, rapid analysis, usability in a wide variety of concentrations and temperatures have positive potential in the wine industry. With standardized methods for food analysis being too work-intensive and time-consuming for the fast market demand, the main purpose of this study was to gain an understanding of the possible benefits that voltammetry can provide to the wine industry. This review paper focused its discussion on the different voltammetric methods, parametric conditions, and electrochemical behavior of essential compounds from wine as the main substance of interest. In particular, the limit of detection (LOD), initial voltage peak, pH levels, working electrodes, and their respective reagents were taken into account to determine the applicable methods that can be utilized in the wine industry. This study could serve as a point of reference for future research into the topic.

Nanomaterials, including carbon nanotubes, graphene oxide, metal–organic frameworks, metal nanoparticles, and porous carbon, play a crucial role as efficient carriers to enhance enzyme activity through substrate channeling while improving enzyme stability and reusability. However, there are significant debates surrounding aspects such as enzyme orientation, enzyme loading, retention of enzyme activity, and immobilization techniques. Consequently, these subjects have become the focus of intensive research in the realm of multi-enzyme cascade reactions. Researchers have undertaken the challenge of creating functional in vitro multi-enzyme systems, drawing inspiration from natural multi-enzyme processes within living organisms. Substantial progress has been achieved in designing multi-step reactions that harness the synthetic capabilities of various enzymes, particularly in applications such as biomarker detection (e.g., biosensors) and the development of biofuel cells. This review provides an overview of recent developments in concurrent and sequential approaches involving two or more enzymes in sequence. It delves into the intricacies of multi-enzyme cascade reactions conducted on nanostructured electrodes, addressing both the challenges encountered and the innovative solutions devised in this field.

The measurement of biosignals in the clinical and healthcare fields is fundamental; however, conventional electrodes pose challenges such as incomplete skin contact and skin-related issues, hindering accurate biosignal measurement. To address these challenges, conductive hydrogels, which are valuable owing to their biocompatibility and flexibility, have been widely developed and explored for electrode applications. In this study, we fabricated a conductive hydrogel by mixing polyethylene glycol diacrylate (PEGDA) with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) polymers dissolved in deionized water, followed by light-triggered crosslinking. Notably, this study pioneered the use of a PEGDA−PEDOT:PSS hydrogel for electrocardiogram (ECG) monitoring- a type of biosignal. The resulting PEGDA−PEDOT:PSS hydrogel demonstrated remarkable conductivity while closely approximating the modulus of skin elasticity. Additionally, it demonstrated biocompatibility and a high signal-to-noise ratio in the waveforms. This study confirmed the exceptional suitability of the PEGDA−PEDOT:PSS hydrogel for accurate biosignal measurements with potential applications in various wearable devices designed for biosignal monitoring.

The horizontal flatbed electrophoresis method is employed to separate protein samples, providing greater flexibility for various electrophoretic applications and easier sample loading compared to its vertical counterpart. In the currently available equipment setup, cathode and anode electrodes are positioned on top of a gel at each end. Since an electric field enters the gel from the top, its strength gradually weakens from the top to the bottom of the gel. When examining the interior of gels following electrophoretic separation, the uneven electric field causes the protein bands to lie down forward in the direction of migration, leading to an increase in bandwidth. This issue has remained unaddressed for several decades. To address this problem, new clamp-shaped and double-deck electrodes were developed to apply an electric field simultaneously from both the top and bottom of the gel. Both of these new electrodes facilitated the formation of perpendicular protein band shapes and enhanced resolution at a comparable level. Due to their ease of use, double-deck electrodes are recommended. By combining these new electrodes with the field inversion gel electrophoresis (FIGE) technique, the protein bands could be focused and aligned nearly vertically, resulting in the highest level of electrophoretic resolution. Our electrodes are compatible with polyacrylamide gels of varying sizes, buffer systems, and sample well formats. They can be easily manufactured and seamlessly integrated into existing laboratory instruments for practical use.

Waste wood, which has a large amount of cellulose fibers, should be transformed into useful materials for addressing environmental and resource problems. Thus, this study analyzed the application of waste wood as supercapacitor electrode material. First, cellulose fibers were extracted from waste wood and mixed with different contents of graphene nanoplatelets (GnPs) in water. Using a facile filtration method, cellulose papers with GnPs were prepared and converted into carbon papers through carbonization and then to porous activated carbon papers containing GnPs (ACP−GnP) through chemical activation processes. For the morphology of ACP−GnP, activated carbon fibers with abundant pores were formed. The increase in the amount of GnPs attached to the fiber surfaces decreased the number of pores. The Brunauer–Emmett–Teller surface areas and specific capacitance of the ACP−GnP electrodes decreased with an increase in the GnP content. However, the galvanostatic charge–discharge curves of ACPs with higher GnP contents gradually changed into triangular and linear shapes, which are associated with the capacitive performance. For example, ACP with 15 wt% GnP had a low mass transfer resistance and high charge delivery of ions, resulting in the specific capacitance value of 267 Fg−1 owing to micropore and mesopore formation during the activation of carbon paper.

Silver nanowires (AgNWs) are a potential alternative to conventional transparent conductive materials for various applications, such as flexible and transparent electrodes in optoelectronic devices, including touch screens, solar cells, and flexible displays. However, AgNW electrodes face degradation due to environmental factors, electrical instability, and mechanical stress. To overcome these challenges, strategies to protect AgNW-based electrodes via the incorporation of polymeric materials were widely investigated to improve the durability and stability of AgNW-based electrodes. This review paper gives a comprehensive overview of the incorporation of polymeric materials with AgNW electrodes, emphasizing their performance, and applications. We compare the different polymeric materials and their effect on the electrical, optical, and mechanical properties of AgNW electrodes. Furthermore, we evaluate the key factors affecting the choice of protective layers, such as their compatibility with AgNWs, and also we present current challenges and future opportunities for the development of polymeric materials for AgNW electrodes in emerging technologies.

In energy application technology, the anode part of the electrode is typically composed of carbon-coated materials that exhibit excellent electrochemical performance. The carbon-coated electrodes facilitate electrochemical reactions involving the fuel and the oxidant. Energy electrodes are used in stationary power plants to generate electricity for the grid. These large-scale installations are known as distributed generation systems and contribute to grid stability and reliability. Understanding the practical applications of energy materials remains a significant hurdle in the way of commercialization. An anode electrode has one key limitation, specifically with alloy-type candidates, as they tend to exhibit rapid capacity degradation during cycling due to volume expansion. Herein, biomass-derived carbon from sunflowers (seeds husks) via pyrolysis and then bismuth nanoparticles are treated with carbon via a simple wet-chemical method. The electrode Bi@C offers several structural advantages, such as high capacity, good cycling stability, and exceptional capability at the current rate of 500 mA g−1, delivering a capacity of 731.8 mAh g−1 for 200 cycles. The biomass-derived carbon coating protects the bismuth nanoparticles and contributes to enhanced electronic conductivity. Additionally, we anticipate the use of low-cost biomass with hybrid composition has the potential to foster environment-friendly practices in the development of next-generation advanced fuel cell technology.

Currently, efficient utilization of low-grade thermal energy is a great challenge. Thermoelectricity is an extremely promising method of generating electrical energy from temperature differences. As a green energy conversion technology, thermo-electrochemical cells (TECs) have attracted much attention in recent years for their ability to convert thermal energy directly into electricity with high thermal power. Within TECs, anions and cations gain and lose electrons, respectively, at the electrodes, using the potential difference between the hot and cold terminals of the electrodes by redox couples. Additionally, the anions and cations therein are constantly circulating and mobile via concentration diffusion and thermal diffusion, providing an uninterrupted supply of power to the exterior. This review article focuses mainly on the operation of TECs and recent advances in redox couples, electrolytes, and electrodes. The outlook for optimization strategies regarding TECs is also outlined in this paper.

In the drying process of electrodes for lithium-ion batteries, the layer structure is defined and can only be influenced slightly in the subsequent process steps. An essential point in the drying process is the fixation of the binder, ensuring both the adhesive and cohesive strength of the electrode. It is known that high drying rates lead to the segregation of the binder in the direction of the coating surface, which results in reduced mechanical stability of the electrode. In a previous publication, an experimental approach was used to investigate the underlying processes that influence binder migration. These results are now used in a model-based approach to describe the binder migration using the convection–diffusion equation. The convective term originates from the shrinkage behavior of the layer during drying due to the relative movement between the active material particles and the solvent in which the binder is dissolved or dispersed; it is expected to be the cause of the binder migration. The diffusive term, representing the binder movement in the solvent, counteracts segregation. The interaction of these forces is simulated at different drying temperatures and the associated drying rates.

In electrical discharge machining (EDM), the tool electrode is one of the substantial components of the system, and it ensures the success or failure of the EDM process. The electrode’s role is to conduct electrical charges and erode the workpiece to the desired shape. Different electrode materials have different impacts on machining. Certain electrode materials remove metal quickly but wear out rapidly, while others degrade slowly but the material removal is too slow. The choice of the electrode has an influence on both the mechanical properties, such as metal removal rate (MRR), wear rate, surface finish, surface modification and machinability, and the electrical properties, such as sparking initiation, time lag, gap contamination and process stability. There are factors to consider when fabricating an electrode, which include the type of workpiece materials, the metallurgical alloying of the materials, the choice of fabrication techniques, the intended use of the electrode, and material cost. Considerable challenges in EDM electrode fabrication have been reported, which include excessive tool wear for green compact electrodes, high toughness for sintered electrodes, and poor rigidity for additively manufactured electrodes. To address these issues, researchers have explored different manufacturing methods, such as casting, conventional machining, electrodeposition, powder metallurgy and additive manufacturing. In this paper, the various techniques attempted and adopted in EDM electrode manufacturing are analyzed and discussed. This paper also sought to give insight into EDM, its various forms, the dielectric fluid’s properties, EDM electrode’s size and shape, the effects of the electrode on the EDM process, material removal, electrode wear, present technologies for electrode fabrication, and the limitations of these technologies. Finally, directions for future research are highlighted.

The synthesis of zinc oxide (ZnO) was accomplished from zinc borate (Zn3B2O6) minerals to be used as electrodes in supercapacitor applications. The concentrations of obtained zinc (Zn) metal after treatment with hydrochloric acid (HCl) were determined by atomic absorption spectroscopy (AAS). Direct synthesis of ZnO on a nickel (Ni) foam surface was conducted by employing the hydrothermal technique using a solution with the highest Zn content. The results showed the successful synthesis of ZnO nanorods on the surface of Ni foam with an average wall size of approximately 358 nm. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements revealed that the synthesized electrode exhibited battery-type charge storage characteristics, reaching a maximum specific capacitance of approximately 867 mF·cm−² at a current density of 2 mA·cm−². Additionally, the energy and power densities of the electrode at a current density of 2 mA·cm−² were calculated as 19.3 mWh·cm−² and 200 mW·cm−², respectively. These results exhibited promising performance of the single-component electrode, outperforming the existing counterparts reported in the literature.

Reduced graphene oxide (rGO) has attracted attention as an active electrode material for flexible electrochemical devices due to its high electric conductivity and large surface area. Compared to other reduction processes, laser reduction is a precise, low-cost, and chemical-free process that is directly applied to graphene oxide (GO) membranes. This study aims to develop rGO through laser irradiation for application as electrodes in thin flexible electrochemical sensors. Laser irradiation parameters will be optimized to achieve reduction of a low oxygen to carbon (O/C) ratio and surface impedance. The influence of humidity on the impedance of rGO electrodes will be studied. The observed instability of the rGO electrode is related to incomplete reduction and oxygenated defects involved in reduction. Partially removed oxygenated functional groups not only influence the impedance of the electrode but make it sensitive to the humidity of the working environment. The result provides references for GO’s laser reduction optimization, demonstrates the potential of applying rGO as an electrode in sensing applications, but also reveals the limitation of applying the laser reduced rGO electrode in a non-constant humidity environment.

Globally, environmental and energy conservation concerns have sparked a push for more efficient and long-term energy sources. Researchers worldwide have put significant effort into developing supercapacitor-based energy storage devices by fabricating electrode materials from affordable porous carbon. The advantages of porous carbons are low-cost processes, high porosity, high surface area, facilitation of surface modification, high conductivity, high mechanical stability, high chemical stability, facilitation of fast ion transport, high rate capability, and high specific capacitance. Using them as electrodes in supercapacitors (SCs) may lead to better performance in specific capacitance and long-term cyclic stability. This study focuses on the recent development of electrode materials for SCs using porous carbons obtained from several diverse sources, such as biomass, polymers, lignite, metal salts, melamine, etc. Therefore, the topic of this review is the most current development of electrode materials for SCs applications. SCs were subjected to a battery of electrochemical tests, which focused on their performance from a crucial perspective, concentrating on the porous carbon’s surface area and surface functional groups. The report also highlights the supercapacitor’s prospects and challenges.

The design of metal-supported solid oxide fuel cells (MS-SOFCs) has again aroused interest in recent years due to their low cost of materials, strength, and resistance to thermal cycling, as well as the advantages of manufacturability. MS-SOFCs are promising electrochemical devices for hydrogen energy. Compared to SOFCs, where ceramic electrodes or electrolytes are used as a carrier base, they are of great interest due to their fast start-up capability, greater reliability, mechanical stability, and resistance to the thermal cycle. MS-SOFCs have many advantages over conventional ceramic-based SOFCs, with the selection of metal-based electrode materials (anode, cathode) and their degradation processes being some of the biggest challenges facing researchers. Therefore, this review reports on the state of the latest research on MS-SOFCs with various structures, discusses the corresponding electrode materials and their existing problems, and puts forward topical issues that need to be addressed in MS-SOFCs.

The hydrothermal synthesis of a nanosized NiCo2O4 oxide with several levels of hierarchical self-organization was studied. Using X-ray diffraction analysis (XRD) and Fourier-transform infrared (FTIR) spectroscopy, it was determined that under the selected synthesis conditions, a nickel-cobalt carbonate hydroxide hydrate of the composition M(CO3)0.5(OH)·0.11H2O (where M–Ni2+ and Co2+) is formed as a semi-product. The conditions of semi-product transformation into the target oxide were determined by simultaneous thermal analysis. It was found by means of scanning electron microscopy (SEM) that the main powder fraction consists of hierarchically organized microspheres of 3–10 μm in diameter, and individual nanorods are observed as the second fraction of the powder. Nanorod microstructure was further studied by transmission electron microscopy (TEM). A hierarchically organized NiCo2O4 film was printed on the surface of a flexible carbon paper (CP) using an optimized microplotter printing technique and functional inks based on the obtained oxide powder. It was shown by XRD, TEM, and atomic force microscopy (AFM) that the crystalline structure and microstructural features of the oxide particles are preserved when deposited on the surface of the flexible substrate. It was found that the obtained electrode sample is characterized by a specific capacitance value of 420 F/g at a current density of 1 A/g, and the capacitance loss during 2000 charge–discharge cycles at 10 A/g is 10%, which indicates a high material stability. It was established that the proposed synthesis and printing technology enables the efficient automated formation of corresponding miniature electrode nanostructures as promising components for flexible planar supercapacitors.

Strontium and cobalt-free LaNi0.6Fe0.4O3–δ is considered one of the most promising electrodes for solid-state electrochemical devices. LaNi0.6Fe0.4O3–δ has high electrical conductivity, a suitable thermal expansion coefficient, satisfactory tolerance to chromium poisoning, and chemical compatibility with zirconia-based electrolytes. The disadvantage of LaNi0.6Fe0.4O3–δ is its low oxygen-ion conductivity. In order to increase the oxygen-ion conductivity, a complex oxide based on a doped ceria is added to the LaNi0.6Fe0.4O3–δ. However, this leads to a decrease in the conductivity of the electrode. In this case, a two-layer electrode with a functional composite layer and a collector layer with the addition of sintering additives should be used. In this study, the effect of sintering additives (Bi0.75Y0.25O2–δ and CuO) in the collector layer on the performance of LaNi0.6Fe0.4O3–δ-based highly active electrodes in contact with the most common solid-state membranes (Zr0.84Sc0.16O2–δ, Ce0.8Sm0.2O2–δ, La0.85Sr0.15Ga0.85Mg0.15O3–δ, La10(SiO4)6O3–δ, and BaCe0.89Gd0.1Cu0.01O3–δ) was investigated. It was shown that LaNi0.6Fe0.4O3–δ has good chemical compatibility with the abovementioned membranes. The best electrochemical activity (polarization resistance about 0.02 Ohm cm2 at 800 °C) was obtained for the electrode with 5 wt.% Bi0.75Y0.25O1.5 and 2 wt.% CuO in the collector layer.

The global population has increased over time, therefore the need for sufficient energy has risen. However, many countries depend on nonrenewable resources for daily usage. Nonrenewable resources take years to produce and sources are limited for generations to come. Apart from that, storing and energy distribution from nonrenewable energy production has caused environmental degradation over the years. Hence, many researchers have been actively participating in the development of energy storage devices for renewable resources using batteries. For this purpose, the lithium-ion battery is one of the best known storage devices due to its properties such as high power and high energy density in comparison with other conventional batteries. In addition, for the fabrication of Li-ion batteries, there are different types of cell designs including cylindrical, prismatic, and pouch cells. The development of Li-ion battery technology, the different widely used cathode and anode materials, and the benefits and drawbacks of each in relation to the most appropriate application were all thoroughly studied in this work. The electrochemical processes that underlie battery technologies were presented in detail and substantiated by current safety concerns regarding batteries. Furthermore, this review collected the most recent and current LIB recycling technologies and covered the three main LIB recycling technologies. The three recycling techniques—pyrometallurgical, hydrometallurgical, and direct recycling—have been the subject of intense research and development. The recovery of valuable metals is the primary goal of most recycling processes. The growth in the number of used LIBs creates a business opportunity to recover and recycle different battery parts as daily LIB consumption rises dramatically.

One of the most important problems in the development of proton exchange membrane fuel cells remains the selection of an efficient electrocatalyst support capable of providing a low loading of active metal with minimal changes in the electrochemical surface, electronic conductivity, and activity. In this work, carbon nanotube arrays (CNTAs) grown directly on commercial gas diffusion layers (GDLs) are used to form electrodes of a new type. The CNTAs are used in the electrode as a microporous layer. The catalytic layer is formed in the microporous layer by a method that does not destroy the carbon support structure and consists of the controlled impregnation of CNTAs with the Pt-precursor with subsequent reduction in platinum particles in the surface volume of the layer. The resulting electrode was studied by scanning/transmission electron microscopy and Raman spectroscopy. This electrode provides increased electrical conductivity of the layer and can also improve stability and longer service life due to the enhanced adhesion of carbon materials to the GDL.

The vanadium redox flow battery (VRFB) has been regarded as one of the best potential stationary electrochemical storage systems for its design flexibility, long cycle life, high efficiency, and high safety; it is usually utilized to resolve the fluctuations and intermittent nature of renewable energy sources. As one of the critical components of VRFBs to provide the reaction sites for redox couples, an ideal electrode should possess excellent chemical and electrochemical stability, conductivity, and a low price, as well as good reaction kinetics, hydrophilicity, and electrochemical activity, in order to satisfy the requirements for high-performance VRFBs. However, the most commonly used electrode material, a carbonous felt electrode, such as graphite felt (GF) or carbon felt (CF), suffers from relatively inferior kinetic reversibility and poor catalytic activity toward the V2+/V3+ and VO2+/VO2+ redox couples, limiting the operation of VRFBs at low current density. Therefore, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. Here, we give a brief review of recent progress in the modification methods of carbonous felt electrodes, such as surface treatment, the deposition of low-cost metal oxides, the doping of nonmetal elements, and complexation with nanostructured carbon materials. Thus, we give new insights into the relationships between the structure and the electrochemical performance, and provide some perspectives for the future development of VRFBs. Through a comprehensive analysis, it is found that the increase in the surface area and active sites are two decisive factors that enhance the performance of carbonous felt electrodes. Based on the varied structural and electrochemical characterizations, the relationship between the surface nature and electrochemical activity, as well as the mechanism of the modified carbon felt electrodes, is also discussed.

Background: Pelotherapy is the traditional procedure of applying curative muds on the skin’s surface—shown to have a positive effect on the human body and cure illnesses. The effect of pelotherapy is complex, functioning through several mechanisms, and depends on the skin’s functional condition. The current research objective was to develop a methodology and electrodes to assess the passage of the chemical and biologically active compounds of curative mud through human skin by performing electrical bioimpedance (EBI) analysis. Methods: The methodology included local area mud pack and simultaneous tap water compress application on the forearms with the comparison to the measurements of the dry skin. A custom-designed small-area gold-plated electrode on a rigid printed circuit board, in a tetrapolar configuration, was designed. A pilot study experiment with ten volunteers was performed. Results: Our results indicated the presence of an effect of pelotherapy, manifested by the varying electrical properties of the skin. Distinguishable difference in the measured real part of impedance (R) emerged, showing a very strong correlation between the dry and tap-water-treated skin (r = 0.941), while a poor correlation between the dry and mud-pack-treated skin (r = 0.166) appeared. The findings emerged exclusively in the frequency interval of 10 kHz …1 MHz and only for R. Conclusions: EBI provides a promising tool for monitoring the variations in the electrical properties of the skin, including the skin barrier. We foresee developing smart devices for promoting the exploitation of spa therapies.

Fuel cell efficiency can be improved by using progressive electrodes and electrolytes. Green nanomaterials and green technologies have been explored for the manufacturing of high-performance electrode and electrolyte materials for fuel cells. Platinum-based electrodes have been replaced with green materials and nanocomposites using green fabrication approaches to attain environmentally friendly fuel cells. In this regard, ecological and sustainable electrode- and electrolyte-based membrane electrode assemblies have also been designed. Moreover, green nanocomposites have been applied to form the fuel cell electrolyte membranes. Among fuel cells, microbial fuel cells have gained research attention for the incorporation of green and sustainable materials. Hence, this review essentially focuses on the potential of green nanocomposites as fuel cell electrode and electrolyte materials and application of green synthesis techniques to attain these materials. The design of and interactions with nanocomposites have led to synergistic effects on the morphology, impedance, resistance, power density, current density, electrochemical features, proton conductivity, and overall efficiency. Moreover, we deliberate the future significance and challenges of the application of green nanocomposites in electrodes and electrolytes to attain efficient fuel cells.

Background and Objectives: Prostate cancer is on the rise in the European Union, and radiofrequency ablation (RFA) is one of the minimally invasive treatment options used for its treatment. Therefore, the aim of this study was to investigate and analyze the effects of RFA on prostate tissues. Materials and Methods: A standard prostate RFA procedure was performed on 13 non-purebred dogs in three sessions: no cooling (NC), cooling with a 0.1% NaCl solution (C.01), and cooling using a 0.9% NaCl solution (C.09). Microtome-cut 2–3 µm sections of prostate samples were stained with hematoxylin and eosin and further examined. Results: A histopathologic evaluation identified four zones of exposure: direct, application, necrosis, and transitional, as the damage on tissues decreased going further from the ablation site. The areas and perimeters of these zones were calculated, and geometric shapes of ablative lesions were evaluated using the quotient formula. Areas and perimeters of prostate tissue lesions in the NC and C.09 sessions were of similar size, whereas those found in C.01 were statistically significantly smaller. Lesions observed in session C.01 were of the most regular geometric shape, while the most irregular ones were found in session C.09. The shapes of lesions closest to the ablation electrode were the most irregular, becoming more regular the further away from the electrode they were. Conclusions: Prostate RFA leads to tissue damage with distinct morphological zones. Notably, the prostate lesions were the smallest and the most regular in shape after RFA procedures using the 0.1% NaCl cooling solution. It can be argued that smaller ablation sites may result in smaller scars, thus allowing for faster tissue healing if the blood flow and innervation at the ablation site are not compromised.

MgCo2O4 nanomaterial is thought to be a promising candidate for renewable energy storage and conversions. Nevertheless, the poor stability performances and small specific areas of transition-metal oxides remain a challenge for supercapacitor (SC) device applications. In this study, sheet-like Ni(OH)2@MgCo2O4 composites were hierarchically developed on nickel foam (NF) using the facile hydrothermal process with calcination technology, under carbonization reactions. The combination of the carbon–amorphous layer and porous Ni(OH)2 nanoparticles was anticipated to enhance the stability performances and energy kinetics. The Ni(OH)2@MgCo2O4 nanosheet composite achieved a superior specific capacitance of 1287 F g−1 at a current value of 1 A g−1, which is higher than that of pure Ni(OH)2 nanoparticles and MgCo2O4 nanoflake samples. At a current density of 5 A g−1, the Ni(OH)2@MgCo2O4 nanosheet composite delivered an outstanding cycling stability of 85.6%, which it retained over 3500 long cycles with an excellent rate of capacity of 74.5% at 20 A g−1. These outcomes indicate that such a Ni(OH)2@MgCo2O4 nanosheet composite is a good contender as a novel battery-type electrode material for high-performance SCs.

Carbon nanotube (CNT)-based electrodes in flexible supercapacitors have received significant attention in recent years. Carbon nanotube fiber fabrics (CNT-FF) have emerged as promising materials due to their high surface area, excellent conductivity, and mechanical strength. Researchers have attempted to improve the energy density and rate performance of CNT-FF supercapacitor electrodes through various strategies, such as functionalization with conductive materials like MnO2 nanoparticles and/or incorporation of graphene into them. In addition, the utilization of CNTs in combination with thin metal film electrodes has also gained widespread attention. Research has focused on enhancing electrochemical performance through functionalizing CNTs with conductive materials such as graphene and metal nanoparticles, or by controlling their morphology. This review paper will discuss the recent developments in supercapacitor technology utilizing carbon nanotube-based electrodes, including CNT fiber fabrics and CNTs on thin metal film electrodes. Various strategies employed for improving energy storage performance and the strengths and weaknesses of these strategies will be discussed. Finally, the paper will conclude with a discussion on the challenges that need to be addressed in order to realize the full potential of carbon nanotube-based electrodes in supercapacitor technology.

Currently, aqueous zinc-ion batteries, with large reserves of zinc metal and maturity of production, are a promising alternative to sustainable energy storage. Nevertheless, aqueous solution has poor frost resistance and is prone to side reactions. In addition, zinc dendrites also limit the performance of zinc-ion batteries. Biomass, with complex molecular structure and abundant functional groups, makes it have great application prospects. In this review, the research progress of biomass and its derived materials used in zinc-ion batteries are reviewed. The different regulation strategies and characteristics of biomass used in zinc-ion battery electrodes, electrolyte separators and binders are demonstrated. The regulation mechanism is analyzed. At the end, the development prospect and challenges of biomass in energy materials application are proposed.

The primary purpose of this study was to produce an ore-based high-capacity supercapacitor electrode. For this, chalcopyrite ore was first leached with nitric acid, and then metal oxide synthesis was carried out immediately on nickel foam using a hydrothermal technique from the solution. Cauliflower-patterned CuFe2O4 with a wall thickness of about 23 nm was synthesized on the Ni foam surface, characterized by XRD, FTIR, XPS, SEM, and TEM investigations. The produced electrode also displayed a feature of a battery-like charge storage mechanism with a specific capacity of 525 mF cm−2 at 2 mA cm−2 current density, energy of 8.9 mWh cm−2, and a power density of 233 mW cm−2. Additionally, even after 1350 cycles, this electrode still performed at 109% of its original capacity. The performance of this finding is 255% higher than that of the CuFe2O4 in our earlier investigation; despite being pure, it performs far better than some of its equivalents in the literature. Obtaining such performance from an electrode made from ore indicates that the use of ore has a lot of potential for supercapacitor production and property improvement.

The surface microstructure of a catalyst coating layer directly affects the active area, hydrophilicity and hydrophobicity, and the high porosity is desirable especially for solid–liquid–gas three-phase catalytic reactions. However, it remains challenging to customize catalyst distribution during the coating process. Here, we report a simple strategy for achieving ultrafine nanocatalyst deposition in a porous structure via introducing the surfactant into coating inks. For a proof-of-concept demonstration, we spin-coated the nanoscale IrO2 sol with a surfactant of sodium dodecyl sulfate (SDS) onto the glassy carbon (GC) electrode for oxygen evolution reaction (OER). Due to the surfactant action, the deposited IrO2 nanocatalyst is evenly distributed and interconnected into a highly porous overlayer, which facilitates electrolyte permeation, gas bubble elimination and active-site accessibility, thus affording high-performance OER in alkaline media. Particularly, the SDS-modified electrodes enable the industrial-level high-current-density performance via enhanced mass transfer kinetics. Such manipulation is effective to improve the coating electrodes’ catalytic activity and stability, and scalable for practical applications and suggestive for other gas-evolving electrodes.

Electrical Impedance Tomography (EIT) is a detection imaging technology developed 30 years ago. When the conventional EIT measurement system is used, the electrode and the excitation measurement terminal are connected with a long wire, which is easily affected by external interference, and the measurement result is unstable. In this paper, we developed a flexible electrode device based on flexible electronics technology, which can be softly attached to the skin surface for real-time physiological monitoring. The flexible equipment includes an excitation measuring circuit and electrode, which eliminates the adverse effects of connecting long wires and improves the effectiveness of measuring signals. At the same time, the design also uses flexible electronic technology to make the system structure achieve ultra-low modulus and high tensile strength so that the electronic equipment has soft mechanical properties. Experiments have shown that when the flexible electrode is deformed, its function is completely unaffected, the measurement results remain stable, and the static and fatigue performances are satisfactory. The flexible electrode has high system accuracy and good anti-interference.

NaH2PO4-MnO2-PbO2-Pb vitroceramics were studied usinginfrared (IR), ultraviolet-visible (UV-Vis) and electron paramagnetic resonance (EPR) spectroscopies to understand the structural modifications as potential candidates for electrode materials. The electrochemical performances of the NaH2PO4-MnO2-PbO2-Pb materials were investigated through measurements of cyclic voltammetry. Analysis of the results indicates that doping with a suitable content of MnO2 and NaH2PO4 removes hydrogen evolution reactions and produces a partial desulphatization of the anodic and cathodic plates of the spent lead acid battery.

This work presents the design and test of an e-textile based functional electrical stimulation system for post-stroke upper limb rehabilitation. The prototype was tested on five stroke survivors to assess stimulation comfort, the stimulation intensity required to achieve hand opening, and ease of use. Wrist extension was measured using two inertial measurement units. The wearable e-textile prototype achieved similar stimulation comfort compared to high-quality hydrogel electrodes with a score difference of between 0 and 1. The stimulation intensity to achieve full hand opening was the same for the hydrogel electrodes and the e-textiles for all five participants. A second design based on a knitted sleeve has been assessed in terms of usability. Additional new designs have been proposed to improve the usability.

Indium tin oxide (ITO) is currently the most widely used material for transparent electrodes; however, it has several drawbacks, including high cost, brittleness, and environmental concerns. Silver nanowires (AgNWs) are promising alternatives to ITO as materials for transparent electrodes owing to their high electrical conductivity, transparency in the visible range of wavelengths, and flexibility. AgNWs are effective for various electronic device applications, such as touch panels, biosensors, and solar cells. However, the high synthesis cost of AgNWs and their poor stability to external chemical and mechanical damages are significant challenges that need to be addressed. In this review paper, we discuss the current state of research on AgNW transparent electrodes, including their synthesis, properties, and potential applications.