Electrode Matrix Research Articles

Dynamics of functional impairments during focal transient ischemia in three-dimensional cortical space

Ischemic injury in the cerebral cortex results in decreased electrical activity across all frequency bands and the emergence of abnormal electrophysiological patterns, including spreading depolarization (SD) and negative ultraslow potential (NUP) [1, 2]. Despite this, the specific dynamics of these changes in electrical activity within the three-dimensional cortical space during ischemia remain incompletely described and poorly understood. To simultaneously investigate changes in electrical activity across the layers of the cerebral cortex and in the horizontal cortical space, we used two linear 16-channel silicone probes (Neuronexus, USA) in combination with a flexible transparent 60-channel matrix of subdural electrodes (MIPT, Russia) and intrinsic optical signal imaging (IOS, 665 nm, transillumination mode) during focal ischemia induced by intracortical injection of the potent vasoconstrictor endothelin-1 (ET-1, 1 μL, 1 μM). These experiments were carried out in head-restrained rats under urethane anesthesia (1.5 g/kg). Formation of the ischemic lesion following ET-1 administration was correlated with clusters of SDs that demonstrated considerable variability in their propagation patterns within both vertical and horizontal planes. The initial SDs originated from the injection site of ET-1 and diffused across all cortical layers. Subsequently, the initiation point of the ensuing SDs gradually shifted towards the deeper layers while the electrical activity showed inadequate recovery between SDs within the injection site. SDs originating in the surrounding cortex did not invade the area near the injection point. Instead, they tended to spread around, often compartmentalizing in the superficial layers of the cortex. Some SDs were observed deep in the cortex, while others were detected on the surface via superficial electrodes and IOS, without leaving typical intracortical electrode traces. Electrographic activity was significantly depressed, especially in the superficial layers around the injection site, three hours after ET-1 administration. However, it returned to pre-ET-1 levels at the remote site, with a spatial gradient observed in subdural electrodes. Functional impairments corresponded to the histological lesion observed in coronal brain sections. Recently discovered NUPs were initiated by SD and were most prominent in the electrodes closest to the ET-1 injection site. These NUPs reached their maximal amplitude at one hour and subsided three hours after ET-1 injection. Our research indicates intricate dynamics in the creation of an ischemic focal point. The data gathered suggest that the emergence of cerebral harm during focal ischemia is associated with the growth of a focus extending both horizontally and vertically across cortical dimensions. This growth is fueled by the generation of SDs within the ischemic penumbra.

Hydrogen peroxide electrosynthesis with nickel foam electrodes: influence mechanism of surface oxidation

AbstractBACKGROUNDNickel foam (NF) is widely used as battery electrode matrix and electrochemical process cathode. However, the surface of NF is prone to oxidation, which may affect its ability to reduce oxygen and produce H2O2, but the influence mechanism is still unclear. In this paper, surface oxidation of the NF was regulated by pickling and drying pretreatment, and the surface oxides were characterized by X‐ray photoelectron spectroscopy (XPS) and energy dispersive X‐ray spectrometry (EDS). The NF was used as the substrate, graphite powder as the catalyst, and PTFE as the binder to prepare graphite‐coated NF composite electrodes. The effect of NF surface oxidation on their ability to generate H2O2 was investigated.RESULTSThe results demonstrated that after pickling and drying, the NF surface generated a large amount of NiO, which increased the charge transfer resistance of the NF by 20.3%, and accelerated further reduction decomposition of H2O2. The rotating ring‐disk electrode (RRDE) tests further confirmed that NiO can reduce the two‐electron oxygen reaction selectivity, which was detrimental to H2O2 electrosynthesis. The graphite‐coated NF composite electrode with pristine NF as the substrate can produce 869.1 mg L−1 of H2O2 and maintain relatively good reusability.CONCLUSIONOverall, the surface oxidation of NF is not conducive to H2O2 electrosynthesis, and it is necessary to prevent oxidation during electrode preparation. This study provides a valuable reference for the preparation of NF electrodes and can promote the further study of in situ H2O2 electrosynthesis. © 2023 Society of Chemical Industry (SCI).

Wood‐Like Low‐Tortuosity Thick Electrode for Micro‐Redoxcapacitor with Ultrahigh Areal Energy Density and Steady Power Output

AbstractConventional MXene‐based thick electrodes with stacked and tortuous microstructures suffer from sluggish charge transport and low‐utilization of active substances, thus a limited boost in areal energy density of the assembled micro‐supercapacitors (MSCs). Herein, the duplication of wood‐like microstructure is realized in MXene/Ag‐nanowires (AgNWs) hybrid aerogel electrode (WL‐M/A‐AE) via directional freeze‐drying technique. Benefitting from the uniform 3D vertically‐aligned microchannels as the highways for ions transport throughout the matrix, the WL‐M/A‐AE with a thickness of up to 2000 µm can achieve a 50‐times higher of Cl− diffusion coefficient relative to closely restacked film electrode with the same mass loading of MXene. Furthermore, the evenly interspersed AgNWs serving as percolation network within the electrode matrix can facilitate horizontal electrons transmission between vertically‐aligned loose MXene flakes, while reversibly capture/release Cl− ions via phase conversion (Ag⇔AgCl) to raise the charge storage capacity of the WL‐M/A‐AE. Thus, when coupling with Zn anode, the assembled micro‐redoxcapacitor adopting polyacrylamide/ZnCl2+NH4Cl hydrogel electrolyte can deliver an areal energy density up to 292.5 µWh cm−2 in a more stable way (a smooth discharge plateau contributing 40.9% of the energy). The demonstrated hybrid thick electrode with wood‐like low‐tortuosity microstructure promises an effective avenue for tackling the performance bottlenecks facing traditional MSCs.

Electrochemical Residence Time Distribution as a Diagnostic Tool for Redox Flow Batteries

The fluid dynamic and electrochemical performance of redox flow batteries (RFBs) stems from the relationship between the flow field and the porous electrode, whose interplay determines how active species move and react during device operation. While characterization techniques, such as residence time distribution, offer insights into species mobility within a reactive volume for a traditional chemical reactor, electrochemical reactors also enable simultaneous measurement of the redox reactions, unlocking another dimension of analysis. Herein, we demonstrate how potentiodynamic measurements, using injections of electrolyte examined through moment analysis, can provide electrode-specific performance scaling relationships across a matrix of carbon paper and cloth electrodes with flow through and interdigitated flow fields. We further combine experimental campaigns with multiphysics simulations to demonstrate how electrode surface area can be estimated with this technique, which we then validate with activated and unactivated commercial carbon cloth electrodes. These studies reveal the multiscale observations that potentiodynamic measurements afford, augmenting existing electrochemical techniques for holistic electrochemical reactor diagnostics.

Target-Induced Electrochemical Sensor Based on Foldable Aptamer and MoS2@MWCNTs-PEI for Enhanced Detection of AFB1 in Peanuts.

Herein, a sensitive and selective electrochemical sensor based on aptamer folding was constructed to detect aflatoxin B1 (AFB1) in peanuts. Specifically, polyethylenimine-functionalized multiwalled carbon nanotubes modified with molybdenum disulfide (MoS2@MWCNTs-PEI) were used as the electrode matrix to enable a large specific surface area, which were characterized by the Randles-Sevcik equation. Additionally, AuNPs were used to immobilize the aptamer via the Au-S covalent bond and provide a favorable microenvironment for signal enhancement. Methylene blue (MB) was modified at the proximal 3' termini of the aptamer as the capture probe, while the signal transduction of the sensor was obtained through changes in conformation and position of MB induced by the binding between AFB1 and the probe. Changes in spatial conformation could be recorded by electrochemical methods more readily. This electrochemical aptasensor demonstrated remarkable sensitivity to AFB1 with an extensive detection range (1 pg/mL to 100 ng/mL) and a lower limit detection (1.0 × 10-3 ng/mL). Moreover, using the constructed aptasensor, AFB1 was identified successfully in peanut samples, with recoveries ranging from 95.83 to 107.53%, illustrating its potential use in determining AFB1 in food.

Detection of Microbes in Ice Using Microfabricated Impedance Spectroscopy Sensors

During the growth of a polycrystalline ice lattice, microorganisms partition into veins, forming an ice vein network highly concentrated in salts and microbial cells. We used microfabricated electrochemical impedance spectroscopy (EIS) sensors to determine the effect of microorganisms on the electrochemical properties of ice. Solutions analyzed consisted of a 176 μS cm−1 conductivity solution, fluorescent beads, and Escherichia coli HB101-GFP to model biotic organisms. Impedance spectroscopy data were collected at −10 °C, −20 °C, and −25 °C within either ice veins or ice grains (i.e., no veins) spanning the sensors. After freezing, the fluorescent beads and E. coli were partitioned into the ice veins. The corresponding impedance data were discernibly different in the presence of ice veins and microbial impurities. The presence of microbial cells in ice veins was evident by decreased electrical characteristics (electrode polarization between electrode and ice matrix) relative to solid ice grains. Further, this electrochemical behavior was reversed in all bead-doped solutions, indicating that microbial processes influence sensor response. Linear mixed-effects models empirically corroborated the differences in polarization associated with the presence and absence of microbial cells in ice. We show that EIS has the potential to detect microbes in ice and differentiate between veins and solid grains.

Zeolite integrated carbon paste sensors for sensitive and selective differential pulse voltammetric determination of carprofen

The present research demonstrates the development and the electroanalytical performance of a novel carprofen (CAR) voltammetric carbon paste electrode (CPEs). Fortification of the electrode matrix with zeolite (ZY) nanostructures with an effective electrocatalytic activity catalyzes the oxidation of the CAR molecule at the ZY/CPEs surface in the universal buffer pH 5 with irreversible anodic oxidation peak at 0.954 V following a diffusion-electrode reaction mechanism. The postulated electrooxidation mechanism of CAR molecule undergoes through oxidation of the enamine N atom (N6) through the transfer of the delocalized lone pair of electrons in addition to the involvement of one proton as estimated from the electrochemical behavior of CAR at different scan rates, pH values and sustained with the molecular orbital calculations. Calibration graphs were linear within the CAR concentration ranged from 16.6 to 323.3 ng mL−1 recording a limit of detection (LOD) value of 5.6 ng mL−1. The cited ZY/CPEs showed enhanced performance, high measurement reproducibility, ease of construction and regeneration of the electrode surface, with a prolonged operational lifetime. Based on the recorded sensitivity and selectivity, ZY/CPEs were utilized for simultaneous quantification of CAR in the presence of various interferents and degradation products. The presented voltammetric analytical technique was tested for monitoring of CAR residues in veterinary and biological samples with acceptable recoveries values compared with the official chromatographic techniques.

Exploitation of bis(tert‐butylaminomethyl)pyridine as a chemical modifier in a carbon paste electrode for sensitive and selective potentiometric determination of Al3+ ion in pharmaceutical and water samples

AbstractThe fabrication of a novel bis(tert‐butylaminomethyl)pyridine pincer ligand‐based ionophore in a carbon paste electrode (CPE) matrix for Al3+ ions was investigated. With a Nernstian slope of 20.05±0.27 mV decade−1 and a low detection limit of 1.0×10−7 mol L−1, the electrode demonstrated an excellent response for the Al3+ ion over a broad concentration range from 1.0×10−7 to 1.0×10−1 mol L−1. The formula for the graphite paste that produced the greatest results was 69.44 % graphite, 27.78 % tricresyl phosphate (TCP) binder, and 2.78 % ionophore. This pincer ligand‐based electrode worked well with aqueous Al3+ solutions that had pH values between 2.5 and 5.5. It may be used for at least 4 months without any detectable potentials digression and has a reasonably quick response time (5 s). The suggested graphitic paste electrode demonstrated strong Al3+ ion selectivity over a broad range of other cations. The isothermal coefficient of the electrode, which was determined to be 0.2884×10−3 V °C−1, was calculated by looking at the impact of test solution temperature on electrode potentials. The suggested electrode was also applied to non‐aqueous media with an aqueous‐non‐aqueous volume ratio of up to 75 : 25. The data acquired using this CPE as an indicator electrode for the potentiometric measurement of Al3+ ions in several actual samples was equivalent to that attained using atomic absorption spectroscopy (AAS).

An Electrochemical-Thermal-Mechanical Model for Large Format Lithium Ion Batteries

The intercalation reaction in Lithium-Ion batteries causes significant volume changes in the active material phases during cycling. Due to spatial limitations in common battery applications, this entails mechanical stresses on different length scales and thereby influencing performance and lifetime of the battery[1]. Mechanical effects are closely linked to electrochemical and thermal processes in the cell, giving rise to complex interactions that are difficult to predict. Moreover, large cell dimensions, which become ever so common in today’s battery industry, further increase complexity due to local variations of state variables. Therefore, modeling is essential to enhance understanding of the governing- and limiting processes.In this contribution we present a fully coupled multi-scale-, multi-physics-model that combines an electrochemical model on the particulate electrode level, namely an extended Newman model featuring a particle size distribution, and a homogenized cell material model, displaying anisotropic electrical-, thermal- and mechanical properties. To include mechanical effects into a multi-physics-model[2] a new approach is considered. We apply the poroelastic theory to describe the mechanical behavior governed by the interaction of the porous electrode matrix and the infiltrated electrolyte. The use of homogenization techniques allows to keep the computational effort in check, while still doing justice to the complexity of a three-dimensional-, multi-scale-, and multi physics problem. The model is parametrized in-house by applying different electrochemical-, mechanical-, and microstructural characterization methods. The model, its parameterization and validation as well as selected simulation results will be presented. Acknowledgements This work was funded by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the research training group SiMET (281041241/GRK2218).[1] Y. Zhao, P. Stein, Y. Bai, M. Al-Siraj, Y. Yang, B.-X. Xu, Journal of Power Sources 2019, 413, 259–283.[2] A. Schmidt, D. Oehler, A. Weber, T. Wetzel, E. Ivers-Tiffée, Electrochimica Acta 2021, 393, 1–14.

Dynamics of High-Density Unipolar Epicardial Electrograms During PFA.

Pulsed field ablation (PFA) is a novel nonthermal cardiac ablation technology based on irreversible electroporation (IRE). While areas of IRE lead to durable lesions, the surrounding regions, where reversible electroporation occurs, recover. The behavior of local electrograms in areas of different electroporation levels remains unknown. The goal of this study is to characterize electrogram dynamics after PFA in IRE and reversible electroporation areas. A total of 6 domestic swine were used. PFA was applied in the epicardium of the right and left ventricles using a focal monopolar catheter. Additional radiofrequency ablations were performed. Epicardial unipolar electrograms were acquired at baseline and for 60 minutes post PFA/radiofrequency ablation using a high-density electrode matrix attached to the epicardium. Electrogram dynamics were analyzed in areas corresponding to different levels of electroporation. Acute lesion formation was assessed after 3 to 5 hours by triphenyl tetrazolium chloride staining. Electrogram analysis demonstrated a clear association between electrogram changes and the level of electroporation. Immediately after PFA, electrograms displayed the following: a significant decrease in R/S-wave amplitude; a large elevation of the ST-segment; and a large decrease in their |(dV/dt)|max. Marked changes in electrograms were observed beyond the lesion area. Thereafter, a gradual recovery was observed. The evolution of all the electrogram parameters throughout the 60 minutes after PFA was significantly different (P<0.05) between the IRE and reversible electroporation areas. Acute lesion staining showed significantly larger depth for PFA lesions compared with radiofrequency ablation. This study shows that unipolar electrograms can differentiate between reversible electroporation and IRE areas during the first 30 minutes post ablation. Differences after the first 30 minutes are less evident. Our findings could result useful for immediate lesion assessment after PFA and warrant further investigation.

An "on-off-on" electrochemiluminescence aptasensor based on a self-enhanced luminophore for ochratoxin A detection.

A highly selective and sensitive "on-off-on" electrochemiluminescence (ECL) aptasensor based on a self-enhanced luminophore was developed for the detection of ochratoxin A (OTA). Specifically, polyethyleneimine functionalized multi-walled carbon nanotubes decorated with gold nanoparticles (AuNPs-PEI-MWCNTs) were used as the electrode matrix to accelerate electron transfer and provide a favorable microenvironment for self-enhanced luminophore loading and ECL signal enhancement. In addition, black phosphorus quantum dots (BPQDs) were used as co-reactants of the ECL reagent tris (2,2'-bipyridyl) ruthenium(II) (Ru(bpy)32+) in ECL experiments, and the reaction mechanism was investigated. The self-enhanced luminophore Ru@SiO2-BPQDs was obtained by encapsulating Ru(bpy)32+ in silica (SiO2) nanoparticles and then combining it with BPQDs through electrostatic interaction. In conventional ECL systems, the emitter and its co-reactants reacted via the inter-nanoparticle pathway, leading tolong distance electron transfer. However, the electron transfer distance in the self-enhanced luminophore was significantly shortened due to the intra-nanoparticle electron transfer pathway because BPQDs and oxidized Ru(bpy)32+ were bound within one nanoparticle, thereby improving ECL efficiency to achieve the first "switch-on" state. Then, the luminophore was quenched using ferrocenes (Fc) modified on anaptamer to achieve the "switch-off" state. Finally, OTA was specifically identified by the adapter, causing Fc to be released from the sensor interface, restoring the ECL intensity to achieve the second "switch-on" state. Under optimal conditions, the aptasensor exhibited good sensitivity, stability, and reproducibility, with a linear detection range from 0.1 to 320ng/mL and a detection limit of 0.03ng/mL. The novel ECL aptasensor provided a common analytical tool for the detection of mycotoxins and other small molecules.

Carrier Transport Regulation of Pixel Graphene Transparent Electrodes for Active-Matrix Organic Light-Emitting Diode Display.

Integrating a graphene transparent electrode (TE) matrix with driving circuits is essential for the practical use of graphene in optoelectronics such as active-matrix organic light-emitting diode (OLED) display, however it is disabled by the transport of carriers between graphene pixels after deposition of a semiconductor functional layer caused by the atomic thickness of graphene. Here, the carrier transport regulation of a graphene TE matrix by using an insulating polyethyleneimine (PEIE) layer isreported. The PEIE forms an ultrathin uniform film (≤10nm) to fill the gap of the graphene matrix, blocking horizontal electron transport between graphene pixels. Meanwhile, it can reduce the work function of graphene, improving the vertical electron injection through electron tunneling. This enables the fabrication of inverted OLED pixels with record high current and power efficiencies of 90.7cd A-1 and 89.1lm W-1 , respectively. By integrating these inverted OLED pixels with a carbon nanotube-based thin-film transistor (CNT-TFT)-driven circuit, an inch-size flexible active-matrix OLED display isdemonstrated, in which all OLED pixels are independently controlled by CNT-TFTs. This research paves a way for the application of graphene-like atomically thin TE pixels in flexible optoelectronics such as displays, smart wearables, and free-form surface lighting.

Dynamics of local unipolar electrograms during epicardial pulsed field ablation (PFA)

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Instituto de Salud Carlos III Background The use of irreversible electroporation (IRE) as a method for cardiac ablation in the treatment of cardiac arrhythmias, known as Pulsed Field Ablation (PFA), has rapidly moved from preclinical studies to clinic. The reference indicator of acute lesion formation during cardiac ablation with thermal techniques consists in recording the local electrical activity changes. In the case of PFA, modifications in the electrical activity have been observed in areas that are not permanently damaged (reversible electroporation) but this is still poorly characterized. Of particular interest from a clinical perspective is to determine how and when the electrical activity of the reversible electroporation areas recovers after PFA. Purpose The purpose of this work was to simultaneously characterize the dynamic evolution of local electrograms after PFA in areas exposed to different levels of tissue damage. Methods High-density local unipolar electrograms were acquired at baseline, and continuously and during 60 min after each PFA application. The measurements were performed in different points of the right and left ventricular epicardial surface of 5 swine weighing 57±8 kg using an open-chest approach following the Principles of laboratory animal care" (NIH Publication no. 85-23 revised 1985). Under general anesthesia, a median sternotomy was made to create a surgical window. Unipolar electrograms were recorded using a 128-channel electrode matrix attached to the epicardial surface. For PFA ablation, a standard 8F, 3.5 mm tip monopolar catheter was positioned in the region corresponding to the center of the electrode array and a return electrode patch was attached to the back of the animals (see Fig. 1). At least 3 hours after the last ablation point, animals were euthanized and tissue was processed and stained with Triphenyltetrazolium Chloride (TTC) to assess acute lesion morphology. Results Our results show an immediate change in the morphology of unipolar electrograms: from basal biphasic electrograms to monophasic electrograms displaying a sudden ST-segment elevation (from 0.0±0.3 mV to 5.9±1.7mv; p&amp;lt;0.01), reduction in the R-S amplitude (from 3.4±3.3 mV to 0.3±0.2 mV; p&amp;lt;0.01) and reduction in the maximum derivative of the QRS-complex (from 3051±2473 mV/s to 394±242 mV/s; p&amp;lt;0.01). Interestingly, the extent and dynamics of the observed changes clearly depended on the ablation level (distance from the ablation point) (see Fig 2.). Conclusions Our observations confirmed that the electrical activity of the reversible electroporation area was also acutely modified while the recovery dynamics were different from the irreversible damaged areas. Our preliminary analysis suggests that the different recovery dynamics observed could help in differentiating between reversible and irreversible electroporation areas.

Activity and stability of bifunctional perovskite/carbon-based electrodes for the removal of antipyrine by electro-Fenton process

Bifunctional perovskite/carbon-black(CB)/polytetrafluoroethylene(PTFE) electrodes for electro-generation and catalytic decomposition of hydrogen peroxide to oxidizing hydroxyl radicals have been fabricated. These electrodes were tested for electroFenton (EF) removal of antipyrine (ANT) as a model antipyretic and analgesic drug. The influence of the binder loading (20 and 40 wt % PTFE) and type of solvent (1,3-dipropanediol and water) was studied for the preparation of CB/PTFE electrodes. The electrode prepared with 20 wt % PTFE and water exhibited a low impedance and remarkable H2O2 electro-generation (about 1 g/L after 240 min, a production rate of ca. 6.5 mg/h·cm2). The incorporation of perovskite on CB/PTFE electrodes was also studied following two different methods: i) direct deposition on the CB/PTFE electrode surface and ii) addition in the own CB/PTFE/water paste used for the fabrication. Physicochemical and electrochemical characterization techniques were used for the electrode's characterization. The dispersion of perovskite particles in the own electrode matrix (method ii) exhibited a higher EF performance than the immobilisation onto the electrode surface (method i). EF experiments at 40 mA/cm2 and pH 7 (non-acidified conditions) showed ANT and TOC removals of 30% and 17%, respectively. The increase of current intensity up to 120 mA/cm2 achieved the complete removal of ANT and 92% of TOC mineralisation in 240 min. The bifunctional electrode also proved high stability and durability after 15 h of operation.

A new approach to electrochemical sensing of a wildly used antibiotic; ciprofloxacin

Excessive use of antibiotics has conducted to a substantial enhancement in drug-resistant genes. Hence, introducing efficacious devices for antibiotic monitoring can ameliorate the life quality. Thus, a valid feasible sensor was developed for ciprofloxacin (CIP) determination using the synergistic interaction of graphene nanosheets (GR NSs) and Fe3O4 nanoparticles (Fe3O4NPs) in the matrix of carbon paste electrode (CPE). Field emission scanning electron microscope (FESEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques were utilized to evaluate the sensor’s electrochemical features. As a result of the excellent properties of the applied nanostructures, the prepared sensor exhibited enhanced electrocatalytic activity. Quantitative analysis of CIP also provided detection and quantification limits of 1.8 nM and 6 nM, respectively. Moreover, the selectivity, sensitivity, stability, repeatability, and reproducibility were successfully examined. These desirable outcomes along with the extraordinary performance of GR/Fe3O4NPs/CPE in real samples promise to provide a reliable device in food and environmental applications.

Novel deliberately sensitive and selective penciclovir voltammetric sensors depending on iron oxide nanoparticles carbon paste electrodes

The present study described the construction and electroanalytical characterization of a novel penciclovir (PCV) voltammetric carbon paste sensor fortified with iron oxide nanoparticles (FeONPs/CPEs). Integration of the electrode matrix with iron oxide nanoparticles obviously enhanced the PCV oxidation peak based on its electrocatalytic activity towards the electrooxidation of PCV molecule at the electrode surface. At the optimized pH value, PCV exhibited an irreversible oxidation peak at about 1.03 V following a diffusion–reaction mechanism. Differential pulse voltammograms (DPVs) registered peak current values correlated linearly to the corresponding PCV within the concentration range from 0.09 to 4.656 µg mL−1 PCV with LOD value 0.025 µg mL−1. Based on the electrochemical behavior of PCV at various pH and the scan rate values, and with the aid of molecular orbital calculations, the electrooxidation reaction of PCV molecule undergoes through oxidation of the terminal amino group of the guanine moiety with the participation of one electron and two protons. Based on the reported selectivity and sensitivity of the FeONPs/CPE, PCV can be assayed in pharmaceutical formulations, biological fluids and surface water samples with average recoveries agreeable with the official HPLC-UV method.

Theoretical and experimental approaches to the preparation, characterization and application of a newly synthesized mesoporous Zn-MOF as a selective ionophore for Ni(II) ion in carbon paste electrode matrix

A novel carbon paste electrode (CPE) chemically modified with a newly synthesized Zn-metal organic framework (Zn-MOF) was synthesized for Ni(II) ion determination with impressing enhancement in sensitivity and selectivity over the preceding studies. Due to their electrocatalytic and substantial surface area criteria, MOFs are a reasonably new category of fascinating materials for precise electrochemical detection. Under the sonication condition, a novel Zn-MOF depending on a Schiff base ligand in nano size was synthesized, and it was characterized using different characterization methods such as powdered X-ray diffraction (PXRD), FT-IR, BET surface area, contact angle and scanning electron microscope (SEM) combined with energy dispersive X-ray analyzer (EDX). The BET surface area and contact angle measurement techniques results were 2901.08 m2 g−1 and 143.49°, respectively, for the synthesized MOF. It was concluded that under the ideal experimental circumstances, the produced Zn-MOF can extract and sense nickel ions from aqueous solution selectively. Several crucial factors were optimized to gain the ultimate electrochemical response. Response mechanism was proved by the aid of study of morphological change and functional groups chemical shifts. Ultimately, a calibration with a Nernstian slope of 28.75 mV decade−1 over linear concentration limits from 5.0 × 10−8 to 1.0 × 10−1 mol L−1 (R2 = 0.9990) and detection limit of 5.0 × 10−8 mol L−1 was obtained. The relative standard deviations and recovery ranges of the proposed approach for determining the Ni(II) ion in various water and food tests (n = 5) were 0.94–2.35% and 97.0–104%, respectively.

Highly self-adhesive, compressible, stretchable, all hydrogel-based supercapacitor for wearable/portable electronics

The increasing popularity of portable/wearable multifunctional electronic devices has highlighted the need for multifunctional power-supply devices. To fulfill this need, we firstly designed a highly self-adhesive and deformable polyacrylamide-based hydrogel electrode. Inspiration by mussels, nanofillers with the design of confined nanospace that formed by the composite of polydopamine-reduced graphene oxide and a compound of cobalt-nickel bimetal oxide and cobalt nitride was involved in the as-prepared hydrogel electrode. This design endows the as-prepared electrode with both the impressive self-adhesive property as well as electrochemical performance. Secondly, a multifunctional all hydrogel-based supercapacitor was assembled by the same as-prepared polyacrylamide hydrogel matrix of electrodes and an electrolyte. The self-adhesive property of both electrode and electrolyte provides a tightly connected interface to ensure structural stability and results in a highly electrical stability during different deformations. Moreover, this multifunctional all hydrogel-based supercapacitor can adhere to the tissue and be used as a functional electronic component as both energy storage and power-supply device. This designed multifunctional supercapacitors can provide insights for further strategies to address energy storage alternatives for portable/wearable electronics.

Decomposition of Phosphorus Pollution and Microorganism Analysis Using Novel CW-MFCs under Different Influence Factors

A constructed wetland (CW)-coupled microbial fuel cell (MFC) system was constructed to treat wastewater and generate electricity. The total phosphorus in the simulated domestic sewage was used as the treatment target, and the optimal phosphorus removal effect and electricity generation were determined by comparing the changes in substrates, hydraulic retention times, and microorganisms. The mechanism underlying phosphorus removal was also analyzed. By using magnesia and garnet as substrates, the best removal efficiencies of two CW-MFC systems reached 80.3% and 92.4%. Phosphorus removal by the garnet matrix mainly depends on a complex adsorption process, whereas the magnesia system relies on ion exchange reactions. The maximum output voltage and stabilization voltage of the garnet system were higher than those of the magnesia system. Microorganisms in the wetland sediments and electrode also changed considerably. It indicates that the mechanism of phosphorus removal by the substrate in the CW-MFC system is adsorption and chemical reaction between ions to generate precipitation. The population structure of proteobacteria and other microorganisms has an impact on both power generation and phosphorus removal. Combining the advantages of constructed wetlands and microbial fuel cells also improved phosphorus removal in coupled system. Therefore, when studying a CW-MFC system, the selection of electrode materials, matrix, and system structure should be taken into account to find a method that will improve the power generation capacity of the system and remove phosphorus.

Improving Interfaces in All-Solid-State Supercapacitors Using Polymer-Added Activated Carbon Electrodes

Solvent-free all-solid-state supercapacitors have recently received attention. Despite their highly specific capacitance, they suffer issues related to the solid–solid interface that degrade their performance during prolonged cycling. Here, we propose a novel strategy for improving the electrode–electrolyte interface by introducing a small amount of polymer into the activated carbon-based electrode. An electrode composition of 80AC:8SA:7AB:5[PEO0.95 (LiClO4)0.05]—where AC, SA, and AB stand for activated carbon, sodium alginate binder, and acetylene black, respectively—is optimized. A composite membrane—viz., PEO-LiClO4 reinforced with 38 wt% NASICON structured nano crystallites of Li1.3Al0.3Ti1.7(PO4)3—is used as a solid electrolyte. Incorporating a small amount of salt-in-polymer (95PEO-5 LiClO4) in the electrode matrix leads to a smooth interface formation, thereby improving the performance parameters of the all-solid-state supercapacitors (ASSCs). A typical supercapacitor with a polymer-incorporated electrode exhibits a specific capacitance of ~102 Fg−1 at a discharge current of 1.5 Ag−1 and an operating voltage of 2 V near room temperature. These ASSCs also exhibit relatively better galvanostatic charge–discharge cycling, coulombic efficiency, specific energy, and power in comparison to those based on conventional activated carbon.