Electrode Measurements Research Articles

Designer Electrocatalysts for the Oxygen Reduction Reaction with Controlled Platinum Nanoparticle Locality

AbstractFor global deployment of proton exchange membrane fuel cells, achieving optimal interaction between the components of the cathode active layer remains challenging. Studies addressing the effect of nanoparticle location (inside vs outside of pores) on performance and durability mostly compare porous and nonporous carbon supports, thus coming short of decoupling nanoparticle locality from carbon support effects. To address the influence of nanoparticle locality on performance and durability, new carbon‐supported electrocatalysts with designed and distinct nanoparticle localities are presented. The developed methodology allows to place Pt nanoparticles preferentially inside or outside of the mesopores of conductive carbon supports from materials under development at Cabot Corporation. Synthesis protocols are tuned to control nanoparticle size, crystallinity, and loading; this way the effect of Pt locality can be studied for two experimental carbon supports in isolation from all other parameters. For one carbon support, Pt active surface area and activity are significantly lower when nanoparticles are placed inside the pores. In contrast, for another, more graphitic carbon support, placing nanoparticles inside or outside of the carbon pores produces no appreciable difference in active surface area and performance rotating disk electrode measurements. Given their carefully tailored structure, these catalysts provide a framework for evaluating locality‐performance‐durability relationships.

Magnetic field-enhanced two-electron oxygen reduction reaction using CeMnCo nanoparticles supported on different carbonaceous matrices

The current study illustrates the successful synthesis of Ce1.0Mn0.9Co0.1 nanoparticles, characterized through XRD, EPR, magnetization curves, and TEM/HRTEM/EDX analyses. These nanoparticles were then loaded into the carbon Vulcan XC72 and the carbon Printex L6 matrices in varying amounts (1, 3, 5, and 10 % w/w) via wet impregnation method to fabricate electrocatalysts for the 2-electron ORR. Before experimentation, the material was characterized via XPS and contact angle measurements. The electrochemical results produced significant findings, indicating that the electrocatalysts with the nanostructures modifying both carbon blacks notably augmented currents in rotating ring-disk electrode measurements, signifying enhanced selectivity for H2O2 production. Moreover, our research underscored the significant impact of Magnetic Field-Enhanced Electrochemistry, employing a constant magnetic field strength of 2000 Oe, on 2-electron ORR experiments. Particularly noteworthy were the observed results surpassing the ones without the magnetic field, demonstrating heightened currents and improved selectivity for H2O2 production (more than 90 %) facilitated by CeMnCo nanoparticles. These significant findings in electrocatalytic efficiency have practical implications, suggesting the potential for developing more efficient and selective catalysts for the 2-electron ORR.

Electrochemical Analysis of Key Anticancer Herbal Drugs: Progress and Innovations in Emodin, Rutin, Berberine, Shikonin, and Sophoridine

Background: Anticancer herbal drugs have gained significant attention in pharmaceutical research due to their complex chemical profiles and multifaceted therapeutic effects. Electrochemical analysis has emerged as a powerful tool for studying these compounds, offering unique insights into their behavior and properties. Methods: This review examines recent advances in the electrochemical analysis of five key anticancer herbal drugs: emodin, rutin, berberine, shikonin, and sophoridine. Various electrochemical techniques, including cyclic voltammetry, differential pulse voltammetry, and square wave voltammetry, are discussed in relation to their application in detecting and characterizing these compounds. Results: Significant progress has been made in developing highly sensitive and selective electrochemical sensors for these herbal drugs. Nanomaterial-modified electrodes have consistently improved detection limits and expanded linear ranges. Compound-specific innovations in electrode modifications and measurement techniques have been tailored to the unique electrochemical properties of each drug. Conclusion: Electrochemical analysis of anticancer herbal drugs has advanced substantially, offering powerful tools for studying and utilizing these compounds in cancer research and treatment. Future directions include the development of multi-analyte sensors, integration with microfluidic technologies, and application of artificial intelligence for data analysis. Challenges remain in improving the stability of modified electrodes and standardizing protocols for sample preparation and analysis.

Electrochemical glucose sensor based on a phenothiazine derivative mediator with nicotinamide adenine dinucleotide-dependent glucose dehydrogenase

The phenothiazine derivative (M2) was utilized as a redox mediator for the redox processes of the nicotinamide adenine dinucleotide (NAD+) cofactor. The composite solutions were prepared by mixing NAD+-dependent glucose dehydrogenase with NAD+, M2, poly-l-lysine, and glutaraldehyde. Glucose sensors were fabricated by casting various composite solutions onto the reduced graphene oxide-modified gold electrode and additional Nafion coating processes. The composition of electrode materials (ratio and amount of each component) and measurement conditions (applied potential, pH, and temperature) were optimized to obtain the highest sensitivity. The sensor showed a low reference effect, high selectivity toward interfering species, and long-term stability. The glucose sensor performed well when human serum was injected as the actual sample and compared with a standard solution. These findings promote the development of electrochemical sensors based on other NAD+-dependent enzymes.

Impact of Nickel on Iridium-Ruthenium Structure and Activity for the Oxygen Evolution Reaction under Acidic Conditions.

Proton exchange membrane water electrolysis (PEMWE) is a promising technology to produce hydrogen directly from renewable electricity sources due to its high power density and potential for dynamic operation. Widespread application of PEMWE is, however, currently limited due to high cost and low efficiency, for which high loading of expensive iridium catalyst and high OER overpotential, respectively, are important reasons. In this study, we synthesize highly dispersed IrRu nanoparticles (NPs) supported on antimony-doped tin oxide (ATO) to maximize catalyst utilization. Furthermore, we study the effect of adding various amounts of Ni to the synthesis, both in terms of catalyst structure and OER activity. Through characterization using various X-ray techniques, we determine that the presence of Ni during synthesis yields significant changes in the structure of the IrRu NPs. With no Ni present, metallic IrRu NPs were synthesized with Ir-like structure, while the presence of Ni leads to the formation of IrRu oxide particles with rutile/hollandite structure. There are also clear indications that the presence of Ni yields smaller particles, which can result in better catalyst dispersion. The effect of these differences on OER activity was also studied through rotating disc electrode measurements. The IrRu-supported catalyst synthesized with Ni exhibited OER activity of up to 360 mA mgPGM -1 at 1.5 V vs RHE. This is ∼7 times higher OER activity than the best-performing IrO x benchmark reported in the literature and more than twice the activity of IrRu-supported catalyst synthesized without Ni. Finally, density functional theory (DFT) calculations were performed to further elucidate the origin of the observed activity enhancement, showing no improvement in intrinsic OER activity for hollandite Ir and Ru compared to the rutile structures. We, therefore, hypothesize that the increased activity measured for the IrRu supported catalyst synthesized with Ni present is instead due to increased electrochemical surface area.

Fabrication of aqueous asymmetric supercapacitor device by using spinel type (FeCoNiCuZn)3O4 high entropy oxide and green carbon derived from plastic wastes

As the world shifts towards renewable energy and more efficient energy storage systems, the demand for advanced materials that can support these technologies has increased. One such promising material class is High Entropy Alloys (HEAs). Unlike conventional alloys, which are typically composed of one or two principal elements, HEAs consist of multiple principal elements in near-equiatomic proportions. Their unique atomic structure, characterized by high configurational entropy, endows them with enhanced stability, tunability, and a high specific surface area—qualities that are highly desirable in supercapacitor applications. HEAs offer significant advantages as supercapacitor electrodes, including increased energy storage capacity, superior electrochemical stability, and the potential for synergistic effects that improve overall performance such as higher energy density, longer cycle life, and greater reliability. FeCoNiCuZn)3O4 has been synthesized by utilizing multiple induction melting process in a quartz tube at 1100 °C, followed by ball milling in order to transform the small pieces into nanostructured powder. The highest specific capacitance obtained is 245.7 F g−1 at 1.5 A g−1 in three electrode measurement system. In addition, plastic biochar was prepared using pyrolysis techniques from plastic wastage. Moreover, it is utilized for supercapacitor application, which shows a maximum specific capacitance of 180 F g−1 at 1 A g−1 for three electrode system. The combing above two electrode materials, the fabricated asymmetric device shows a maximum specific capacitance of 58 F g−1 at 1 A g−1 for 3M KOH electrolyte with maximum specific energy of 23.44 Wh kg−1 at specific power of 1700 W kg−1.

MOF-Supported Intermetallic Pt-Ni Electrocatalyst for the Oxygen Reduction Reaction

The catalyst support materials demonstrate great influence on the performance and durability of oxygen reduction reaction (ORR) electrocatalysts. Metal organic frameworks (MOFs) have been the focus of many Pt alloyed catalyst supports due to their large surface areas and well-defined pore structures. MOF-based carbon supports and a special class of MOFs that have a zeolite-type structure, and Zeolitic imidazolate frameworks (ZIFs) offer high ORR activity and enhanced stability of Pt-alloyed catalysts due to their porous structure, large surface area, and good electrical conductivity. In this study, we used two different MOF-based supports, Mn-NC and ZIF-67 derived Co-NC, to synthesize a nitrogen (N)-doped intermetallic PtNi catalyst. The synthesized material exhibits enhanced ORR activity and stability in an acidic electrolyte that is superior to commercial Pt/C catalyst. The rotating disk electrode (RDE) measurements of the PtNi/Co-NC catalyst demonstrated that the mass activity (MA) and specific activity (SA) are 0.9 A mgPt -1 and 1.8 mA cm-2, respectively at 0.9 V. The synthesized PtNi/Mn-NC catalyst demonstrated 1.4 A mgPt -1 and 2.1 mA cm-2 at 0.9 V, which are higher than those achieved with the commercial Pt/C. The MEA performance of the MOF-based PtNi catalysts will also be discussed. The mechanism of the enhanced performance of the catalysts is being formulated, based on in situ X-ray absorption spectroscopy (XAS) analysis. This work provides a promising approach to improve the activity and stability of binary and ternary Pt-based electrocatalysts for ORR by the use of MOF-based supports.

High Surface Area Metal Oxide Enhanced Self-Powered Microfluidic Device for Real-Time Pathological Detection

Biomarkers based sensing in the realm of disease prevention, its diagnosis, and drug development has shown its unique importance in health care. In particular, the platelet level in blood is strongly linked with the development of several kind of severe diseases like coronavirus disease 2019, diabetes, and microbial infections as well as individuals undergoing cancer diagnosis. Currently, commercial methods employed for platelet level determination in whole-blood are based on Coulter principle, flow cytometry, and image analysis. However, these technologies are intricate, time consuming, expensive, and require a trained operator as well as lack of portability. Considering these issues, we have developed a self-powered portable device for real-time platelet level monitoring, aimed towards point-of-care applications. The fabricated self-powered-microfluidic triboelectric nanogenerator (SPM-TENG) utilized test sample flow-resistance for sensing of platelet level and triboelectric voltage output as sensing signal. For the fine tuning of fabricated SPM-TENG, we compared the triboelectric voltage output from gold electrode measurement setup and terminal electrode measurement setup. In view of further improvement in stability, voltage output and to minimize the noise in sensing signals, the geometrical optimization of microfluidic channel was performed. In conclusion we have optimized the device as a terminal electrode measurement setup with copper tubes on terminals of microfluidic channel and copper oxide nanowires grown on the interior of copper tubes. These copper oxide nanowires provide a high surface area for solid-liquid contact separation and is responsible for enhanced sensing signal. The fabricated SPM-TENG has shown its great potential in platelet level sensing with plasma-based samples as well as whole-blood samples. The proposed device demonstrated its practicality towards real-time rapid sensing of platelet level and portability.

FeMnO3/CNT as a synergistic bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions in alkaline medium

The development of highly effective and low-cost electrocatalysts for energy conversion and storage devices is triggered by the sluggish kinetics of oxygen reduction and evolution reactions. Perovskite-based oxides are identified as potential ORR and OER electrocatalysts in an alkaline medium. Thus, the present study discusses the synthesis and characterization of FeMnO3/CNT as a bifunctional catalyst with a low potential gap of 0.89 V. The FeMnO3/CNT composite was synthesized by the solution combustion method and characterized using spectroscopic and electron microscopic techniques. The increase in the ID/IG ratio obtained from the Raman spectra of the FeMnO3/CNT composite with respect to bare CNT indicates the functionalization of CNT. The ORR and OER characteristics of the FeMnO3/CNT composite were analyzed with rotating ring disc electrode and rotating disc electrode measurements. The LSV curve of the FeMnO3/CNT composite synthesized with 0.3g of CNT show better ORR and OER activity. The ORR activity measurements of the composite done in 0.1 M KOH electrolyte show a good onset potential of 0.95 V vs. RHE and a half-wave potential of 0.74 V. The HPRR studies show that the ORR reaction mechanism follows a 2e− + 2e− reduction pathway. The OER measurements in an alkaline medium show an onset potential of 1.63 V vs. RHE with a Tafel slope of 115.3 mV dec−1. Also, this work gives an insight into the fundamental understanding of the synergy between the perovskite and CNT, leading to an enhanced ORR and OER catalytic activity. In addition, the material exhibits good stability for ORR and OER stability studies.

Electrogastrography measurement systems and analysis methods used in clinical practice and research: comprehensive review.

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Au enables PdAu aerogel efficient catalysts for oxygen reduction and C2 alcohol oxidation

Metallic aerogels (MAs) with self-supporting three-dimensional (3D) porous structures constitute a potential platform for the construction of robust catalysts. In this work, we successfully constructed 3D PdAu MAs with the optimized d-band electron of Pd and geometrical lattice expansion using a maneuverable in-situ seed-mediated strategy at room temperature. The introduction of Au accelerated the kinetics of Pd4Au3 MAs toward oxygen reduction reaction (ORR), ethylene glycol oxidation reaction (EGOR), and ethanol oxidation reaction (EOR) in alkaline electrolyte, boosting the activity and stability of Pd4Au3 MAs. The mass activities of Pd4Au3 MAs/C in ORR, EGOR and EOR were 1.74, 8.57, and 9.54 A mgPd−1, respectively, which were remarkably better than those of referenced Pd MAs/C, commercial Pt/C and Pd/C. The rotating ring-disk electrode measurement illustrated that Pd4Au3 MAs/C achieved a 4-electron transfer process in ORR from O2 to OH−. In-situ Fourier transform infrared spectroscopy revealed that Pd4Au3 MAs/C enabled the cleavage of the C–C bonds, thus accomplishing the C1-complete oxidation of 10-electron ethylene glycol and 12-electron ethanol. This study provides an efficient strategy to fabricate binary non-Pt alloy aerogels as high-performance multifunctional electrocatalysts for ORR, EGOR, and EOR.

The Influence of Alkali Cations on the Performance of Pt Electrodes in Kolbe Electrolysis of Acetic Acid

AbstractElectrochemical decarboxylation of carboxylic acids is considered a sustainable method to improve the quality of pyrolysis oil. In this study, we assess the effect of monovalent alkali cations (of the acetates) on the performance of Pt electrodes in acid decarboxylation and the competing OER, using various electrochemical methods. We reveal a strong cation dependence generally following the trend Li+<Na+<K+~Cs+ within a large pH range. Using rotating ring disc electrode measurements, we highlight the strong contribution of the oxygen evolution reaction particularly for electrolytes containing Li+ and Na+ which decreases the selectivity for Kolbe oxidation. In addition, the faradaic efficiency (FE) towards methanol ranges between 16 % (for Li+) and 29 % (for Cs+) at high solution pH (9 or 12). The observed trends are generally explained by a cation‐dependent interfacial pH and surface coverage of acetate, both lowest for Li. This is evident from differences in charge transfer resistance determined by impedance measurements and local pH measurements. Additionally, enhanced dissolution of Pt by Li+ is also proposed. This work highlights that K+ and Cs+ cations favor FE for electrochemical Kolbe oxidation, at relatively low current densities.

Textronic Capacitive Sensor with an RFID Interface.

This article presents an innovative combination of textile electrical circuits with advanced capabilities of electronic RFID sensors, indicating the revolutionary nature of the development of textronics, which is used in various areas of life, from fashion to medicine. A review of the literature relating to the construction of textronic RFID identifiers and capacitive textronic sensors is performed. Various approaches to measuring capacity using RFID tags are discussed. This article focuses on presenting the concept of a capacitive sensor with an RFID interface, consisting of a microelectronic part and a textile part. The textile part is based on the WL4007 material, where antennas and capacitive sensors are embroidered using SPARKFUN DEV 11791 conductive thread. The antenna is a half-wave dipole designed to operate at a frequency of 860 MHZ. The microelectronic part is sewn to the textile part and consists of a microcontroller, an RFID-integrated circuit and a coupling loop, placed on the PCB. The embroidered antenna is coupled with a loop on the microelectronic module. This article focuses on presenting various designs of textronic electrodes, enabling various types of measurements. Article presents capacitance measurements of individual sensor electrodes, made using a measuring bridge and a built RFID tag. The sensors' capacity measurement results are shown.

Transparent ultraviolet photosensor based on vertically aligned ZnO nanorods: The role of the electrode geometry

Ultra-violet (UV) photosensors are commonly used for environmental monitoring and space applications to measure UV radiation in order to mitigate its negative effects. This work investigates the effect of the spacing between the electrodes on the performance and response of UV photosensors. First, ZnO nanorods are thermally grown on a glass substrate with transparent interdigitated electrodes. The surface topography and morphology are characterized using advanced microscopy techniques. The optical properties are explored using UV-Vis and photoluminescence analyses. I-t and I-V measurements in the dark and under UV radiation are carried out to reveal the photosensor characteristics at electrode spacings of 50, 75, 100, 125, and 150 µm. The best photosensor performance is observed at a spacing of 75 µm under a bias voltage of +7 V. The photosensor has a responsivity of 5.06478 mAW−1, photosensitivity of 0.58002 %, gain of 1.0058, rise time of 0.533 s, and decay time of 0.474 s. Regardless of the performance of the photosensors, this study gives an insight into the role of the electrode geometry, including the electrode gap and measurement path, which could be helpful in designing UV photosensors and optimizing their performance.

Detection and Analysis of Abnormal High-Current Discharge of Cylindrical Lithium-Ion Battery Based on Acoustic Characteristics Research

The improvement of battery management systems (BMSs) requires the incorporation of advanced battery status detection technologies to facilitate early warnings of abnormal conditions. In this study, acoustic data from batteries under two discharge rates, 0.5 C and 3 C, were collected using a specially designed battery acoustic test system. By analyzing selected acoustic parameters in the time domain, the acoustic signals exhibited noticeable differences with the change in discharge current, highlighting the potential of acoustic signals for current anomaly detection. In the frequency domain analysis, distinct variations in the frequency domain parameters of the acoustic response signal were observed at different discharge currents. The identification of acoustic characteristic parameters demonstrates a robust capability to detect short-term high-current discharges, which reflects the sensitivity of the battery’s internal structure to varying operational stresses. Acoustic emission (AE) technology, coupled with electrode measurements, effectively tracks unusually high discharge currents. The acoustic signals show a clear correlation with discharge currents, indicating that selecting key acoustic parameters can reveal the battery structure’s response to high currents. This approach could serve as a crucial diagnostic tool for identifying battery abnormalities.

Study of Oxygen Reduction Reaction on Polycrystalline Rhodium in Acidic and Alkaline Media

This study examines the kinetics and mechanism of the oxygen reduction reaction (ORR) on a polycrystalline rhodium electrode (Rh(poly)) in acidic and alkaline media, using rotating disc electrode measurements. This study found that the ORR activity of the Rh(poly) electrode decreases in the order of 0.1 M NaOH > 0.1 M HClO4 > 0.05 M H2SO4 concerning the half-wave potentials. The Tafel slopes for ORR on Rh(poly) in the cathodic direction are 60 and 120 mV dec−1 at low and high overpotentials, respectively, in perchloric acid and alkaline solutions. However, strongly adsorbed sulfate anions hinder the ORR on Rh(poly) in sulfuric acid, leading to higher Tafel slopes. The highest ORR activity of Rh(poly) in an alkaline media suggests the promoting role of the specifically adsorbed OH− anions and RhOH. In all cases, ORR on Rh(poly) proceeds through the 4e-series reaction pathway.

Efficient photocatalytic molecular oxygen activation by TTF-based heterojunction for water purification

Tetrathiafulvalene (TTF), one of the well-known organic photoelectric materials, was served as active sites to accelerate the activation of molecular oxygen to degrade organic pollutants. Herein, a kind of Z-scheme heterojunction photocatalysis was constructed based on g-C3N4 and TTF. According to the experimental results, the mechanism of Z-scheme heterojunction was supported, in which photogenerated electrons transferred from g-C3N4 to TTF. More importantly, TTF on the catalyst surface could serve not only as electron donor, but also as the terminal active site to transfer photoexcited electrons to adsorbed oxygen molecules, producing mass of ⋅O2–. Meanwhile, the activation rate constant of TCN-5 for RhB was 0.0624 min−1, which was 10 and 5 times of g-C3N4 and TTF, respectively. In addition, the results of EPR spectra, rotating disk electrode measurement and molecular oxygen activation measurement also demonstrated that this catalyst was energetically favorable to generate ⋅O2– through the single-electron reduction pathway of molecular oxygen. Finally, four possible photodegradation routes for RhB were proposed based on the results of HPLC-MS. This work provides a new insight on the application of organic photoelectric materials in the purification of wastewater by the molecular oxygen activation.

Iron Triad-Based Bimetallic M–N–C Nanomaterials as Highly Active Bifunctional Oxygen Electrocatalysts

Iron Triad-Based Bimetallic M–N–C Nanomaterials as Highly Active Bifunctional Oxygen Electrocatalysts

Analysis of Kinetic and Ohmic Resistances in PEM Water Electrolysis through Reference Electrode Measurements

We investigated a three electrode setup utilized in a temperature variation study to extract the activation energy for the half-cell reactions in PEM water electrolysis and the contributions of electronic resistances to ohmic resistance. The reference electrode configuration used in this investigation is an improved version of a setup previously introduced by our group. Enhancements have been made to minimize the influence of the reference electrode and improve the accuracy of electrochemical impedance spectroscopy.

Catalyst Interaction in Unitized Regenerative Fuel Cells

Unitized regenerative fuel cells have emerged as promising energy conversion and storage systems for various applications. However, in order to optimize their efficiency, it is crucial to enhance the performance of the bifunctional catalyst. This study aims to provide deeper insights into the electrochemical behavior and performance of the bifunctional catalyst. Several electrocatalysts were prepared and evaluated using rotating disc electrode measurements. The primary focus was placed on investigating the interaction between Pt, Ir, and the support material, antimony doped tin oxide (ATO), and their impact on the oxygen evolution reaction and oxygen reduction reaction. Among the analyzed catalysts, Pt black mixed with synthesized IrO2 supported on developed ATO exhibited the highest performance, considering the results from both the fuel cell and electrolyzer systems.