Conventional Electrodes Research Articles

Poly(3,4-Ethylenedioxythiophene)/Functional Gold Nanoparticle films for Improving the Electrode-Neural Interface.

Implantable neural electrodes are indispensable tools for recording neuron activity, playing a crucial role in neuroscience research. However, traditional neural electrodes suffer from limited electrochemical performance, compromised biocompatibility, and tentative stability, posing great challenges for reliable long-term studies in free-moving animals. In this study, a novel approach employing a hybrid film composed of poly(3,4-ethylenedioxythiophene)/functional gold nanoparticles (PEDOT/3-MPA-Au) to improve the electrode-neural interface is presented. The deposited PEDOT/3-MPA-Au demonstrates superior cathodal charge storage capacity, reduced electrochemical impedance, and remarkable electrochemical and mechanical stability. Upon implantation into the cortex of mice for a duration of 12weeks, the modified electrodes exhibit notably decreased levels of glial fibrillary acidic protein and increased neuronal nuclei immunostaining compared to counterparts utilizing poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate). Additionally, the PEDOT/3-MPA-Au modified electrodes consistently capture high-quality, stable long-term electrophysiological signals in vivo, enabling continuous recording of target neurons for up to 16weeks. This innovative modification strategy offers a promising solution for fabricating low-impedance, tissue-friendly, and long-term stable neural interfaces, thereby addressing the shortcomings of conventional neural electrodes. These findings mark a significant advancement toward the development of more reliable and efficacious neural interfaces, with broad implications for both research and clinical applications.

Efficient synthesis strategy and synergistic effect of Ni-Fe-Ru electrode for boosting alkaline water electrolysis

Hydrogen production from alkaline water electrolysis (AWE) has promising potential in energy storage due to the advantages of low cost and large scale, but its bottleneck is the low current density and poor durability of non-precious metal electrodes. Although numerous electrode designs with superior activity have been reported, the complicated synthesis process and refined microstructure have not changed the high preparation cost, high resistance, and poor durability of conventional AWE electrodes. Here, we report an efficient synthesis strategy of high-density Ni-Fe-Ru electrode (particle size < 5 nm) and explore the synergistic effect between Ni-Fe-Ru elements at different potentials. The electrode exhibits excellent OER activity (264 mV@100 mA cm−2, Tafel slope = 49 mV dec−1) and AWE performance (400 mA cm−2@1.89 V), it can work stably for 300 h at 500 mA cm−2, with potential for industrial applications.

Monolayer Ta2Se: A low-cost catalyst with enhanced stability and high basal plane activity for oxygen reduction reaction

The search for cost-effective two-dimensional (2D) electrocatalysts is accelerating as these materials emerge as pivotal alternatives to traditional energy technologies for fuel cells. In this work, we report a low-cost, high-performance Ta2Se monolayer as an electrocatalyst for the oxygen reduction reaction (ORR) through first-principles calculations. The Ta2Se monolayer exhibits notable stability and low cleavage energy, underscoring its practical potential for experimental synthesis. Our computations show that the Ta2Se monolayer has a metallic band structure with substantial electronic states at the Fermi level, which suggests the favorable electron transport properties. Remarkably, the outer Ta atoms in the basal plane of Ta2Se monolayer are identified as ORR active sites, exhibiting a competitive selection for dissociative and associative four-electron pathways alongside outstanding catalytic activity. Through examining the surface coverage impacts on ORR, we disclose that at a moderate oxygen coverage, the Ta2Se monolayer's limiting potential reaches approximately 0.9 eV, outstripping the conventional Pt electrodes, thus confirming its superior ORR catalytic capability. The low cost, active basal plane sites, and high ORR activity make the Ta2Se monolayer a competitive candidate for advanced fuel cell components.

Hierarchical mesh-type oxygen electrode using carbon nanotube framework for anion-exchange membrane-based unitized regenerative fuel cells

Developing three-dimensional porous oxygen electrodes (OE) is crucial for enhancing round-trip efficiency (RTE) of anion-exchange membrane-based unitized regenerative fuel cells (AEM_URFCs). Herein, a novel OE design of AEM_URFCs is presented based on a hierarchical mesh electrode (HME) with a porous carbon nanotube (CNT) framework. The HME, featuring square-shaped macropores achieved by dispersing catalyst nanoparticles on the CNT framework enhances surface area, mass transport, and electron transport. Half-cell test demonstrated superior oxygen reduction reaction and oxygen evolution reaction activity compared to conventional electrodes. Moreover, the HME maintained stable ORR and OER activity during the stability test. In single-cell tests, the AEM_URFCs with the HME exhibited higher RTE (55% at 20 mA cm−2), surpassing the conventional electrode (52%). Furthermore, RTE was maintained at a remarkable 41% under ultrahigh current density (250 mA cm−2), which is unprecedented in the literature. The AEM_URFCs featuring the HME displayed superior cyclability over 5 cycles and durable performances under both fuel cell and water electrolysis modes.

High Throughput Correlative Electrochemistry-Microscopy Analysis on a Zn-Al Alloy.

Conventional electrodes and electrocatalysts possess complex compositional and structural motifs that impact their overall electrochemical activity. These motifs range from defects and crystal orientation on the electrode surface to layers and composites with other electrode components, such as binders. Therefore, it is vital to identify how these individual motifs alter the electrochemical activity of the electrode. Scanning electrochemical cell microscopy (SECCM) is a powerful tool that has been developed for investigating the electrochemical properties of complex structures. An example of a complex electrode surface is Zn-Al alloys, which are utilized in various sectors ranging from cathodic protection of steel to battery electrodes. Herein, voltammetric SECCM and correlative microstructure analysis are deployed to probe the electrochemical activities of a range of microstructural features, with 651 independent voltammetric measurements made in six distinctive areas on the surface of a Zn-Al alloy. Energy-dispersive X-ray spectroscopy (EDS) mapping reveals that specific phases of the alloy structure, particularly the α-phase Zn-Al, favor the early stages of metal dissolution (i.e., oxidation) and electrochemical reduction processes such as the oxygen reduction reaction (ORR) and redeposition of dissolved metal ions. A correlative analysis performed by comparing high-resolution quantitative elemental composition (i.e., EDS) with the corresponding spatially resolved cyclic voltammograms (i.e., SECCM) shows that the nanospot α-phase of the Zn-Al alloy contains high Al content (30-50%), which may facilitate local Al dissolution as the local pH increases during the ORR in unbuffered aqueous media. Overall, SECCM-based high-throughput electrochemical screening, combined with microstructure analysis, conclusively demonstrates that structure-composition heterogeneity significantly influences the local electrochemical activity on complex electrode surfaces. These insights are invaluable for the rational design of advanced electromaterials.

Enhancing surface integrity and performance of EDM with sustainable dielectrics and electrode modifications

A common non-traditional method for precise machining of hard materials is electro-discharge machining (EDM). The efficiency and surface quality in the EDM process are decided by the design and type of the electrodes. Because of its lightweight, cost-effectiveness and easy machinability, aluminium is employed in a wide range of applications. In this work, AlSi10Mg electrodes are manufactured by different processing routes such as 3D printing, casting, and extrusion. Different characterization techniques are carried out to determine the mechanical, electrical, and thermal properties of all differently processed aluminium alloy electrodes. The processing route influence during the EDM of Ti-6Al-4V is evaluated with different levels of operating parameters using conventional EDM oil and lemon peel biodiesel as dielectrics. The experiments are performed with 3 different levels of current (Ip) and pulse on time (Ton) with a constant voltage. The output responses viz. material removal rate (MRR), Tool wear rate (TWR), average surface roughness (Ra) and white layer thickness (WLT) are considered to compare the EDM performance exhibited by differently processed aluminium alloy electrodes. The 3D printed aluminium alloy electrode produces about 23% less TWR and 18% improved surface quality than the conventional (extruded) electrode. The performance exhibited by the cast aluminium alloy electrode is sub-optimal when compared to electrodes processed by the other two routes. The microscopic examination revealed that WLT could be reduced to the extent of about 29% and 39% with 3D printed AlSi10Mg electrodes when compared with extruded and cast electrodes. The present study concluded that a 3D printed electrode with lemon peel dielectric is the most preferable combination for high surface finish operation.

Soft-metal bonding-enabled recyclable and anti-interference flexible multilayer piezoelectric sensor for tractor tire strain monitoring

Real-time efficient sensing of machine-soil interactions, especially precise tire-ground contact information, plays a critical role in cultivation, seeding, and harvesting for smart agriculture. However, the complicated agricultural environment poses a considerable challenge to traditional rigid sensors, which cannot suffer from both large deformation and electromagnetic interference. Here, we report a novel soft-metal BiInSn bonding-enabled recyclable and anti-interference flexible multilayer piezoelectric sensor for monitoring tractor tire strain. The printed BiInSn-ink electrode fully wraps the surface fibers of porous BaTiO3/PVDF-HFP electrospun films only through a low pressure at low temperature due to its unique thermal-softening effects, which of the adhesion strength is superior to the intrinsic tension limit of the film. The compact multilayer piezoelectric sensor is thus easily prepared, remarkably increasing the output voltage compared to a single-layer case (up to 300% for three layers). Benefiting from the low melting point of the BiInSn alloy, the sensors are easily recyclable compared to conventional metal electrodes prepared with copper, silver, and gold. In addition, its high electrical conductivity also enables the shielding layer to achieve ultrahigh shielding effectiveness of 2100 dB mm−1. This sensor can be demonstrated for tire strain sensing under complex operating conditions such as plowing, harrowing, and fertilizer application. These findings serve as a foundation for accelerating the development of smart agriculture.

Innovative Ethanol Sensors Utilizing Organic Material Patterned Surface Acoustic Wave Detection

In this paper, sensor based on surface acoustic waves for ethanol vapors detection, was fabricated and studied. For room temperature detection of the volatile compound, a novel carbyne nanofilm was deposited on the surface of a SAW transducer. The conventional electrodes were replaced by conductive polymeric coting of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) to minimize the microstructural and elemental difference between the electrode and gas sensitive material. The experimental results showed that the sensors had a good response to ethanol at room temperature. The maximum response of the sensors was at 600 ppm, where the time delay between the output and the input signals of the transducer was ~ 160 μs. The parasitic contact resistance and interface capacitance were found insufficient to affect the accuracy of the measurement, although their values are higher as compared to the sensors with metal electrodes.

Experimental study on enhancing electrostatic charging of nonwoven filter media through novel electrode configurations

The COVID-19 pandemic has underscored the urgent need for efficient particle filtration to tackle public health challenges. This study compares the electrostatic charging capabilities of two types of electrodes: conventional Metal Lamellar Electrodes (MLE) and Modified Lamellar Plate Electrodes (MLPE) with PMMA insulation, in their role of charging nonwoven polypropylene filter media. Experimental analysis unequivocally demonstrates the superiority of MLPE in promoting effective electrostatic charge, as influenced by applied high voltage and inter-electrode distance, resulting in a significant enhancement in fine particle filtration. Numerical simulations of the electric field conducted using the COMSOL software and employing the Finite Element Method (FEM) validate these findings. FEM discretizes the domain into small finite elements and applies Laplace's equation in charge-free regions, providing a comprehensive understanding of the behavior of dual-electrode corona discharge systems. These simulations indicate higher field intensities for MLPE compared to MLE.By integrating experimental and numerical analyses, this study sheds light on the potential benefits of MLPE for air filtration systems, offering a noteworthy advancement in the control of airborne infections and reduction of environmental health risks. This research lays the groundwork for the development of more efficient and durable filtration systems, meeting the increasing demands for public health protection.The findings of this study suggest that the adoption of MLPE could significantly contribute to improving indoor air quality and mitigating the transmission of respiratory diseases. MLPE may also find utility in industrial filtration and air purification in sensitive work environments. Ultimately, this research sets the stage for the development of more efficient and sustainable filtration systems, addressing the growing needs for public health protection.

Comparison of Two Types of Electrodes for Measuring Submental Muscle Activity During Swallowing.

This study aimed to investigate the potential of a newly developed small electrode to accurately record muscle activity during swallowing. This study included 31 healthy participants. The participants underwent swallowing trials with three types of material. The recordings involved the following conditions: 1) swallowing saliva, 2) swallowing 3 mL water, and 3) swallowing 5 mL water. Two types of electrodes, a conventional electrode (CE) and a newly developed small electrode (NE), were symmetrically positioned on the skin over the suprahyoid muscle group, starting from the center. From the surface electromyography data, the swallowing duration (s), peak amplitude, and rising time (duration from swallowing onset to peak amplitude: s) were measured. Additionally, the equivalence of characteristics of the waveform of muscle activities was calculated by using the variance in both the upper and lower confidence limits in duration and rising time. No significant differences in baseline, swallowing duration or rising time between the CE and NE were observed for any swallowing material. The peak amplitude was significantly higher for the NE than for the CE for all swallowing materials. The CE and NE displayed no significant difference in the equivalence of characteristics of the waveform of muscle activities for any swallowing material. The gold-plated small electrodes utilized in this study indicated the ability to record the same characteristics of muscle activity as conventional electrodes. Moreover, it was able to capture the muscle activity of each muscle group with improved sensitivity in a narrow area, such as under the submandibular region, with more precision than that of conventional electrodes.

Extraction of ion beam from laser ion source for direct plasma injection scheme

Laser ion sources are expected to be used in various applications of heavy ion beam technology. The plasma direct injection scheme (DPIS) is a method in which ion beams extracted from a laser ion source are directly injected into a radio frequency quadrupole (RFQ) linear accelerator. In this study, a new shape of the plasma electrode with a concave surface for the DPIS was proposed to inject a converging beam to a cavity of RFQ accelerator. This approach allows the use of a large-diameter extraction electrode, which is not limited by the aperture of the RFQ electrode rods. The DPIS, using the concave surface electrode, was employed to accelerate C6+ ion beams. The results indicated that both the beam current and the number of ions increased nearly twice with the proposed electrode shape compared to values obtained with the conventional electrode. This enhancement corresponded to the increased extraction area of the beam.

The layer-by-layer assembled ERGO+/ERGO− multilayer modified electrode for sensitive detection of dopamine

Graphene materials represented by graphene oxide (GO) have been widely regarded as functional coatings or films to modify surface of the electrode for detecting dopamine molecules. However, interfacial material properties for detection sensitivity, film stability, and applicability to electrodes are still highly desired. Herein, we first present a screen-printing carbon electrode (SPCE) coated with an electrochemically reduced layer-by-layer (LbL) assembled multilayer driven by an electrostatic interaction between positively charged polyethyleneimine-modified GO with amine groups (ERGO+) and negatively charged carboxyl-functionalized GO (ERGO−), which is briefly described as (ERGO+/ERGO−)n/SPCE. Firstly, without using conventional glassy carbon and gold electrodes, SPCE was tried to make coatings adapt to more flexible and unstable electrodes, simultaneously guaranteeing higher detection performance. Secondly, although a variety of electrochemical sensors such as GO−/SPCE and ERGO−/SPCE were obtained through the drop-casting technique, as-prepared (ERGO+/ERGO−)n/SPCE showed much higher electrocatalytic activities with enhanced peak current signals and reduced charge transfer resistance. Finally, excellent electrochemical properties and sensing performances of the (ERGO+/ERGO−)n/SPCE sensor for detection of dopamine were demonstrated, especially having a linear range of 1 μM to 1000 μM. Meanwhile, the detection limit is as low as 0.39 μM and S/N is equal to 3. The present work offers a potential direction to develop GO modified electrodes for sensitive biomolecular detection.

Self-powered photodetector based on 1D TiO2-3D CdS mixed dimensional heterostructure fabricated at low temperature

Solution processed photodetectors have garnered great attention in applications such as, machine vision perception, neuromorphic computing and opto-electronic memory storage. Though, such photodetectors offer several advantages such as ease of fabrication, high scalability, low thermal budget and low-cost processing, multi-modal functionality etc. however, they suffer from the major drawback of inferior device performance −as low responsivity and slow rise time, particularly due to the intrinsic poor crystallinity of the photoactive material. In this work, we demonstrate a solution processed photodetector with impressive performance at comparatively low processing temperatures (<150 °C) based on the mixed dimensional heterostructure configuration of 1D TiO2 nanorods and 3D CdS nanoflowers. TiO2 nanorods have been synthesized by hydrothermal technique, whereas their CdS sensitization is done by chemical bath deposition. Low cost carbon paste is used as electrode instead of conventional non-economic noble metal electrodes. X-ray diffraction studies validated excellent crystallinity of the photoactive material even under low temperature processing condition. The type-II Heterojunction (TiO2 and CdS) configuration photodetector shows efficient response at zero bias, thus yielding a self-powered device. The detector shows response in UV and visible region, with excellent responsivity of 110 mA/W (5 V), 563 µA/W (0 V) and a quicker rise time of 81 ms. Albeit the simple fabrication scheme and low processing temperatures, the detector exhibited promising figures-of-merit, which aids in fabrication of novel solution processed photodetectors.

Suppressing Structure Delamination for Enhanced Electrochemical Performance of Solid Oxide Cells.

Reversible solid oxide cells (rSOCs) have significant potential as efficient energy conversion and storage systems. Nevertheless, the practical application of their conventional air electrodes, such as La0.8Sr0.2MnO3-δ (LSM), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), and PrBa0.8Ca0.2Co2O5+δ (PBCC), remains unsatisfactory due to interface delamination during prolonged electrochemical operation. Using micro-focusing X-ray absorption spectroscopy (µ-XAS), a decrease (increase) in the co-valence state from the electrode surface to the electrode/electrolyte interface is observed, leading to the above delamination. Utilizing the one-pot method to incorporate an oxygen-vacancy-enriched CeO2 electrode into these air electrodes, the uniform distribution of the Co valence state is observed, alleviating the structural delamination. PBCC-CeO2 electrodes exhibited a degradation rate of 0.095mVh-1 at 650°C during a nearly 500-h test as compared with 0.907mVh-1 observed during the 135-h test for PBCC. Additionally, a remarkable increase in electrolysis current density from 636 to 934mAcm-2 under 1.3V and a maximum power density from 912 to 989mWcm-2 upon incorporating CeO2 into PBCC is also observed. BSCF-CeO2 and LSM-CeO2 also show enhanced electrochemical performance and prolonged stability as compared to BSCF and LSM. This work offers a strategy to mitigate the structural delamination of conventional electrodes to boost the performance of rSOCs.

Transforming Waste into Wealth: Advanced Carbon-Based Electrodes Derived from Refinery and Coal By-Products for Next-Generation Energy Storage.

This comprehensive review addresses the need for sustainable and efficient energy storage technologies against escalating global energy demand and environmental concerns. It explores the innovative utilization of waste materials from oil refineries and coal processing industries as precursors for carbon-based electrodes in next-generation energy storage systems, including batteries and supercapacitors. These waste-derived carbon materials, such as semi-coke, coal gasification fine ash, coal tar pitch, petroleum coke, and petroleum vacuum residue, offer a promising alternative to conventional electrode materials. They present an optimal balance of high carbon content and enhanced electrochemical properties while promoting environmental sustainability through effectively repurposing waste materials from coal and hydrocarbon industries. This review systematically examines recent advancements in fabricating and applying waste-derived carbon-based electrodes. It delves into the methodologies for converting industrial by-products into high-quality carbon electrodes, with a particular emphasis on carbonization and activation processes tailored to enhance the electrochemical performance of the derived materials. Key findings indicate that while higher carbonization temperatures may impede the development of a porous structure, using KOH as an activating agent has proven effective in developing mesoporous structures conducive to ion transport and storage. Moreover, incorporating heteroatom doping (with elements such as sulfur, potassium, and nitrogen) has shown promise in enhancing surface interactions and facilitating the diffusion process through increased availability of active sites, thereby demonstrating the potential for improved storage capabilities. The electrochemical performance of these waste-derived carbon materials is evaluated across various configurations and electrolytes. Challenges and future directions are identified, highlighting the need for a deeper understanding of the microstructural characteristics that influence electrochemical performance and advocating for interdisciplinary research to achieve precise control over material properties. This review contributes to advancing electrode material technology and promotes environmental sustainability by repurposing industrial waste into valuable resources for energy storage. It underscores the potential of waste-derived carbon materials in sustainably meeting global energy storage demands.

Mass scale synthesis of graphene nanosheets using waste cardboard for application in perovskite solar cells and supercapacitors

Advanced graphene-based materials have been proficiently incorporated into next-generation solar cells and supercapacitors because of their high electrical conductivity, large surface area, excellent charge-transport ability, and exceptional optical properties. Herein, we report the synthesis of graphene nanosheets (GNs) from waste cardboard via pyrolysis, with ethyl alcohol as the growth initiator. Additionally, we demonstrated the use of GNs in energy conversion and storage applications. Using the GN electrode in perovskite solar cells resulted in an excellent power conversion efficiency of ∼10.41 % for an active area of 1 cm2, indicating an enhancement of approximately 27 % compared to conventional electrodes. Furthermore, the GNs were used as active electrode materials in supercapacitors with excellent electrochemical performance and a high gravimetric specific capacitance of 167.5 F/g at a scan rate of 2 mV/s. The developed GNs can be efficiently used for energy storage, conversion, and electrochemical sensing applications.

High-Bandwidth Lumped Mach-Zehnder Modulators Based on Thin-Film Lithium Niobate

Recently, lumped Mach-Zehnder Modulators (MZMs) have received renewed attention due to their potential for low power consumption and compact size. However, the practicality of lumped MZMs with conventional lumped electrodes (C−LEs) is limited by their lower electro−optical (EO) bandwidth. The reduction in EO bandwidth results from the inherent trade−off between EO bandwidth and half−wave voltage length product (VπL) within the C−LE architecture. This paper proposes a thin−film lithium niobate (TFLN)−based lumped MZM with capacitively−loaded lumped electrodes (CL−LEs). The purely linear EO effect of the LN eliminates the parasitic capacitance in the doped PN junction and enhances the EO bandwidth. Furthermore, the CL−LE structure can break the limitation between EO bandwidth and VπL inherent in the C−LE design. Simulations show the proposed device achieves a high EO bandwidth of 32.4 GHz and a low VπL of 1.15 V·cm. Due to the reduced capacitance and lower VπL, the power consumption of the device is as low as 0.1 pJ/bit. Simulation results indicate that the open−eye diagrams are achieved at 64 Gb/s for 1.5 mm TFLN lumped MZM, with an ER of 2.97 dB. Consequently, the proposed device architecture substantially enhances the performance of lumped MZMs, showing promise for application in short−reach optical interconnects within data centers.

Skin‐Mount Textile‐Based Flexible Strain Sensors for Physiotherapy

Tremendous development in intelligent wearable gadgets creates opportunities for flexible strain sensors. Comfortable and safe flexible strain sensors have high demand in wearable applications and therefore the textile‐based strain sensors are desired. Achieving attributes like easy fabrication, cost‐effectiveness, high sensitivity, good stability, and portability is still a challenge to overcome. In this regard, textile‐based flexible strain sensors, one on jeans fabric and other on cotton fabric, are presented. A conventional interdigitated electrode structure is adopted and sensors are prepared by facile and economical fabrication process. Both sensors own high sensitivity factors, i.e., gauge factor &gt;200 and stability of ≈10 000 cycles. The anticipated works show a linear response R2 = 0.99, low hysteresis &lt;5%, and minimum resolution &lt;7°. The intended sensors are implemented for real‐time application, i.e., the physiotherapy of the knee and neck. The jeans‐fabric‐based sensor is used for knee therapy and the cotton for neck. The daily therapy sessions are recorded and examined. The sensors respond well to the applied strain during therapy sessions, proving to be an outstanding choice for integration into biomedical wearable devices for therapeutic purposes. The proposed sensors can also be auspicious candidates for targeting many other wearable applications.

Imperceptible liquid metal based tattoo for Human-Machine interface on hairy skin

Biopotential signals recorded by skin surface electrodes reflect the state of the body and corresponding organ functions. These signals are commonly utilized in clinical diagnosis, health monitoring, sports training, and human–computer interaction. However, the utilization of conventional electrodes on hairy skin causes a number of issues, including suboptimal skin compliance, obstructed sweat secretion and impaired tactile perception, making it difficult to obtain long-term and high-fidelity biopotential recordings. Here, we propose an imperceptible spray-on electrode tattoo (SE-tattoo) with sweat-permeability, high adhesiveness, high conductivity, and fast curing ability (<20 s). The water-based conductive ink is sprayed directly on the hairy skin to form a conformable conductive tattoo that neither affects nor is affected by the skin hair. We demonstrate it for heart health monitoring, sports training, electro-tactile display and close-loop teleoperation control. The SE-tattoo offers a reliable and versatile solution to biopotential recordings and serves as a promising platform for bidirectional human–machine interaction.One-Sentence Summary: Imperceptible sweat-permeable SE-tattoo enables high-fidelity biopotential recordings for bidirectional human–machine interaction.

Efficient oxidation of hydrazine over electrochemically activated glassy carbon electrode surface: Kinetics and sensing performance

Hazardous chemical hydrazine (HZ) can enter the body through the skin and harm the kidneys and liver. Consequently, it is imperative to accurately determine HZ concentrations in samples. One significant challenge in the direct and sensitive detection of analytes is the higher oxidation overpotential and inferior voltammetric response over the conventional bare electrode surface, attributed to the passivation of the electrode surface. To address this issue, we electrochemically activated (oxidized) a pristine glassy carbon electrode (GCE) in a mild acidic medium. The activated GCE demonstrated improved HZ oxidation efficiency. The activated GCE exhibited a distinct redox pair in 0.1 M H2SO4 because of the growth of C=O groups onto the electrode surface during electrochemical oxidation. We characterized the GCE surface before and after the functionalization using electrochemical processes, Scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). This activated electrode surface was utilized for electrochemical HZ oxidation in an alkaline medium, revealing enhanced electrochemical performance compared to the pristine GCE regarding HZ oxidation following conventional Butler-Volmer kinetics. Thorough electrochemical analyses and characterizations of the sensor were performed utilizing techniques such as Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Open Circuit Potential (OCP), Chronoamperometry (i-t curve), and Differential Pulse Voltammetry (DPV). The correlation between the current response and HZ concentration displayed an extensive linear dynamic range (LDR) spanning from 6 to 1000 μM, boasting a limit of detection (LOD) at 0.48 μM. The sensor's sensitivity was determined to be 3.1 μA μM−1 cm−2. The proposed activated GCE effectively reduces HZ oxidation overpotentials, thereby enhancing its potential application as an anode in direct hydrazine fuel cells.