bluuebunny/crossref_metadata_2025 huggingface dataset:
Guided Phase Transition in Host Formation Reaction for Designing Cathode Materials of Li-Ion Batteries
Authors: Jo Hyoi , Jung Sung-Kyun
Published: December 2024

Conversion reaction-based cathode materials accompanying phase transition from transition metal compounds to lithium compounds and transition metal (MaXb + cLi → dLieX + aM, M: transition metal, X: anion) have been regarded as potential candidates for high-capacity cathodes due to multi-electron transfer reaction compared to intercalation cathode materials (LiMO2, M=Ni, Co, Mn) involving single electron transfer. Conversion reaction cathode materials also have received a lot of attention due to the high degree of freedom of designing the cathode materials according to the numerous combinations of transition metal (M) and anions (X). However, since the conversion reaction involves structural reorganization including phase separation, voltage hysteresis is inevitable due to the compositional inhomogeneity that occurs during the repeated lithiation/delithiation processes. These issues cause large irreversible capacity and progressive capacity degradation. Therefore, to utilize conversion reaction materials, it is desperately necessary to establish a reversible reaction path that can minimize voltage hysteresis and enable long-term cycle stability.

The exploration of materials that separately store lithium ions and electrons has opened a new branch of cathode materials and design strategies through numerous combinations of lithium compounds and transition metal compounds. In certain combinations of these, the anions separated by the electrochemical decomposition of the lithium compound are incorporated into the transition metal compound, which enables to discover the new host of cathode materials polymorphs that can store the lithium and electrons reversibly. Herein, we introduce the mechanism of guided phase transition in host formation reactions inducing the phase transformation of transition metal compounds to a new metastable phase analogous to the original crystal structure. In the LiF-FeF2 composite system, the crystal structure of pristine tetragonal FeF2 successfully guides the phase transition route to reach metastable tetragonal FeF3 rather than the formation of thermodynamically stable rhombohedral FeF3. Induced tetragonal FeF3, due to its structural similarity to discharged FeF2, enables facile phase transitions even during insertion and conversion reactions, thereby reducing compositional inhomogeneity and providing low voltage hysteresis and high reversibility. We believe that guiding the reaction pathway to minimize changes in crystal structure during the charging and discharging processes is essential to evade the irreversible reaction pathway for the conversion reaction cathode materials. Therefore, a deeper understanding of the reaction mechanisms in the LiF-FeF2 nanocomposite provides valuable insights into designing cathode materials with enhanced performance and cycle stability by controlling the reaction pathway and crystal structure.
Fast Li Ion Transportation via Dielectric Nanoislands
Authors: Teranishi Takashi , Toyota Yuji , Higaki Yusuke , Fujisawa Kana , Kondo Shinya , Kishimoto Akira
Published: December 2024

Drastic enhancement in the high rate capability of lithium ion battery up to the level of supercapacitors has been required while maintaining its high energy density, towards the next generation power sources. The strategy to incorporate the dielectric nanoisland including benchmarking dielectric compound, BaTiO3 (BTO), into the active materials–electrolyte interface delivers the ultrafast charge transfer pathway via the dialectic layer [1-3]. A series of experimental results and density functional theory and molecular dynamics (DFT-MD) based calculations demonstrated the activated interfacial charge transfer pathway. For instance, in charging, The solvated Li adsorbed onto the dielectric surface and then desolvated at the same surface. The naked Li preferentially intercalates into the electrode bulk via the triple phase interface (TPI): dielectrics-active materials-electrolyte interface.

The idea of fast charge transfer architecture via the mentioned TPI, involving activated electrochemical reaction on dielectric surface, has been utilized to Li ion batteries (LIB) and capacitors, to further enhance their cell performances. For instance, the BTO nanocube (NC) decoration onto cathodes for LIB yields to many unequalled advantages that the conventional nanoparticles hardly achieve; most importantly, the NC displays a high dispersibility owing to the steric hindrance effect originating from the bulky oleic acids on the NC surface. In fact, the NC with the cube length, ca. 25 nm decorated LiCoO2 (LCO) displays significantly enhanced high rate capability as the LIB cathode. The pulsed-laser-deposition (PLD) based nanodecoration technique also effectively increased TPI density. 3D nanodecorated LCO (BTO nanodots were decorated onto LCO raw powder prior to its processing to form a working cathode) were found to exhibit notably higher capacity retention value at 10C rate, namely ~47% higher than that of their sol-gel processed cathode. The activated dielectric interface was also utilized to the lithium ion capacitor (LIC) cathode, activated carbon (AC). Optimized capacity of the BTO-AC composite was 35% higher than that of the bare AC. The strengthened LIC capacity is responsible for the enhancement of the Li desolvation activities on the dielectric surface, rather than that in the AC micropores.

[1] T. Teranishi et al., Appl. Phys. Lett.,105,143904 (2014). [2] T. Teranishi et al., Adv. Electron. Mater. 4, 1700413 (2018). [3] T. Teranishi et al., J. Power Sources 494, 229710 (2021). [4] T. Teranishi et al., J. Appl. Phys. 131, 124105 (2022). [5] Y. Toyota et al., ACS Appl. Energy Mater. 7, 1440 (2024).
Novel Reduced-Order Electrochemical Models for Lithium-Ion Batteries Integrating Comprehensive Degradation Mechanisms across Various Operational Scenarios
Authors: Gao Tianhan , Lu Wei
Published: December 2024

It is crucial to enhance the computational efficiency while ensuring accuracy in battery simulations, particularly given the presence of degradation factors. We propose reduced order electrochemical models, including a revised single-particle model (RSPM) and fast-calculating P2D (FCP2D) model. They use shape functions to model the lithium-ion concentration and electrolyte potential distribution, and apply the weak form to construct equations for solving the time-dependent polynomial parameters. These two reduced-order electrochemical models have incorporated comprehensive side-reactions, including the anode SEI formation and evolution, anode transitional metal reduction, cathode SEI formation and evolution, cathode film formation and evolution, cathode transitional metal dissolution, and electrolyte oxidation. The performances of the reduced order models are evaluated by comparing the simulation results with those generated by the P2D benchmark model during constant current charging/discharging single cycle, random C-rate operation mode, and dynamic charging/discharging cycling. Results show that the RSPM and FCP2D models can predict the battery performance (e.g., terminal voltage, salt concentration, electrolyte potential) and degradation (e.g., the current density of each side-reaction, the concentration of side-reaction species, cell capacity degradation) accurately and efficiently. The relative error is below 10% while the RSPM and FCP2D demonstrate a much higher calculation efficiency than the P2D benchmark model, with a calculation speed up to ten times faster.
A Solid-State Reference Electrode for High Temperature Molten Salts
Authors: Yuan Yating , Mahurin Shannon , Dai Sheng
Published: December 2024

A reliable and robust reference electrode is essential for electrochemical applications in high-temperature molten salts. However, developing such an electrode is challenging due to strict requirements for chemical and mechanical stability. The current state-of-the-art reference electrode, which employs Ag/AgCl redox, typically requires a container to separate the inner electrolyte from the target electrolyte. This design not only complicates the electrode structure but also heavily relies on the conductivity of the container materials, affecting performance. To overcome this limitation, we have developed a solid-state reference electrode based on the reversible intercalation and de-intercalation of Mg into MnO2. This feature enables direct contact between the reference electrode and the target electrolyte, eliminating the need for the container. The redox reaction involved was studied using various electrochemical techniques and characterization methods. Our study provides valuable insight for designing new reference electrodes for high-temperature molten salts.
In-Situ Monitoring of Molten Chloride Salt Chemistry and Corrosion Using Microelectrode
Authors: Kim Changkyu , Couet Adrien
Published: December 2024

Molten chloride salts have emerged as promising candidates for coolant and energy storage medium applications. However, corrosion presents a significant challenge in their utilization, compounded by the complexities of material selection. This underscores the critical need for in-situ monitoring of molten chloride salt chemistry and corrosion. Such monitoring is essential for advancing nuclear reactor systems, optimizing reactor performance, and ensuring long-term stability. In this context, the integration of microelectrodes for in-situ monitoring of molten chloride salt chemistry and corrosion offers several advantages. Their small size and high spatial resolution enable precise characterization of electrochemical processes at microstructure specific sites at the corroding surfaces, facilitating a deeper understanding of corrosion mechanisms and redox reactions at the electrode-electrolyte interface. Additionally, microelectrodes provide faster response times and lower detection limits, enhancing sensitivity and enabling real-time monitoring of redox kinetics in molten salt systems.

In this study, in-situ redox monitoring in high-temperature molten salts has been explored using microelectrode fabricated with glass-coated 25µm diameter Tungsten microwire. The diffusion coefficients of targeted ions, Eu3+ or Ni2+, in 500°C LiCl-KCl eutectic molten salt has been addressed using cyclic voltammetry with varied scan rate. The electrochemical performance of the fabricated microelectrode has been validated by comparing the diffusion coefficient of the targeted species with those obtained using conventional macro-electrode. Furthermore, the potential applicability of the microelectrode as a high temperature scanning electrochemical microscopy (HT-SECM) for molten salt environment also has been addressed by performing approach curve experiment on Ni-Cr alloys. These results are promising and can be implemented to better understand both molten salt chemistry and grain-level corrosion under aggressive environment, ultimately ensuring the long-term stability of next-generation nuclear reactor system.
(Invited) Modification of Photocatalyst Surface for Selective Conversion of CO2
Authors: Iguchi Shoji , Naniwa Shimpei , Teramura Kentaro
Published: December 2024

Catalytic conversion of CO2 into valu-added products such as CO, HCOOH, HCHO, CH3OH, and CH4 is attracting great attentions as a promising technique for carbon neutrality. In the conventional heterogeneous catalytic processes for the CO2 conversion, it is necessary to use a reducing reagent such as H2 or hydrocarbons under high-temperature conditions. However, the photocatalytic conversion of CO2, regarded as an artificial photosynthesis, mainly use H2O as a more favorable reductant. Among many reported photocatalysts for the conversion of CO2 using H2O as a reductant, number of photocatalysts is limited to those which satisfy the following requirements: (i) origin of CO2 reduction products is confirmed using 13C isotope labeled CO2, (ii) selectivity toward the CO2 reduction products is above 50%, and (iii) stoichiometric O2 (the oxidation product of H2O) is produced. The appropriate modifications of the photocatalyst surface are significant for the improvement in the selectivity of photogenerated electrons toward CO2 reduction, because H2 evolution via reduction of protons (H+) is thermodynamically favorable as compared with CO formation via reduction of CO2. In this presentation, some of the achievements in the photocatalyst development focusing on surface modification will be presented.
Utilizing a High-Efficiency and Durable Electrocatalyst on GaAs for PEC Water Oxidation
Authors: Kang Soon Hyung
Published: December 2024

Gallium arsenide (GaAs) semiconductor photoanode has been the subject of extensive research due to its promising potential for photoelectrochemical water splitting. However, GaAs photoanodes have been severely limited by stability issues, including photocorrosion, light-induced degradation, and oxidation. The oxidation of GaAs can lead to the formation of surface defects, which reduce the photocurrent generation. Herein, we investigate the effects of surface modification of GaAs photoanodes with electrocatalysts consisting small amount of Pt@NiOOH and their mixture, on the PEC oxygen evolution reaction (OER) performance. Among the pristine samples, Pt@NiOOH-modified GaAs photoanodes showed the lowest onset potential for PEC water oxidation. Here, we demonstrate Pt@NiOOH/GaAs photoanodes can exhibit an ultrahigh stability of 200 h at a large photocurrent density (>25 mA cm-2) in 3-electrode configuration under AM 1.5G one-sun illumination and further provide extremely robust protection for the GaAs surface for over time without any performance degradation, i.e., without any loss of photocurrent, onset potential, or efficiency.
A Nitrogen-Doped CuWO4 Photoanode with Oriented Crystal Growth for Efficient Visible-Light-Driven Water Oxidation
Authors: Katsuki Tomohiro , Hoshino Norihisa , Zahran Zaki , Tsubonouchi Yuta , Chandra Debraj , Yagi Masayuki
Published: December 2024

A photoanode capable of efficiently promoting water oxidation is a key essence for realizing a photoelectrochemical (PEC) water splitting system for hydrogen production. Copper tungsten oxide, CuWO4 is a superior photoanode material with a narrower band gap (2.2- 2.4 eV) than BiVO4 (~ 2.4 eV) and WO3 (~ 2.7 eV) studied extensively as photoanodes for water oxidation. In the last decade, many efforts have been devoted to developing efficient CuWO4-based photoanodes by elements doping and surface treatments. However, there has been no report on nitrogen doping CuWO4 for improving its PEC performance. Recently, we have reported a unique preparation technique (a mixed metal-imidazole casting; MiMIC) to form rigidly adhering metal oxides films on electrode substrates by casting precursor methanol solutions (or suspensions) of the corresponding metal ions in the presence of imidazole derivatives followed by annealing.1) Imidazole derivatives were reported to act as a binder for metal oxide nanoparticles to be well-interconnected and nitrogen source for N-doping for synthesis of N-doped BiVO4.2) Herein we report effects of N-doping into a CuWO4 photoanode on its electronic property and PEC performance for efficient water oxidation CuWO4.

The N-doped CuWO4 photoanode was prepared using a MiMIC method. The top view SEM images of the CuWO4 films with different fraction (Fim
= 0 ~ 50%) of imidazole derivatives in precursor solutions showed that the particle size decreased from 1 to 0.1 μm with secondary particle decay. PEC properties were measured using a single-chamber cell in the three-electrode configuration under solar simulated irradiation. The photocurrent density (0.21 mA cm-2 at 1.23 V vs. RHE) for the N-doped CuWO4 photoanode with Fim
of 33% is higher than that (0.04 mA cm-2) for a CuWO4 photoanode (Fim
= 0%). An onset wavelength of an IPCE action spectrum for the CuWO4 photoanode (Fim
= 33%) was longer than the CuWO4 photoanode (Fim
= 0%) due to nitrogen doping.

1) Z. N. Zahran, T. Katsuki, M. Yagi, et al., ACS Appl Energy Mater, 2022, 5, 2, 1894.

2) T. Eo, T. Katsuki, Z. N. Zahran, M. Yagi, et al., ACS Appl Energy Mater, 2021, 4, 4, 2983.
Investigating the Effect of Alkali Metal Cations on Electrochemical Ammonia Oxidation Reaction on Polycrystalline Platinum Electrode
Authors: Bang Junbeom , Ahn Sang Hyun
Published: December 2024

It is widely recognized that hydrogen is an appropriate fuel for the sustainable energy system because it can be utilized as an energy storage material of intermittent renewable energy sources, and it generate no environmentally harmful products after combustion. However, in region where green hydrogen production cannot follow the need, import is necessary. In this case, transportation and storage of pure hydrogen can be a problem because of the high cost of maintaining liquefied state and low amount of hydrogen in compressed gas. In this regard, ammonia has received much attention as a hydrogen carrier with advantageous properties of relatively mild condition for liquefaction, high volumetric density of hydrogen, and no carbon content.

Electrochemical ammonia oxidation reaction (AOR) to extract the hydrogen has been researched as much less energy is required for electrolysis when replacing oxygen evolution reaction to the AOR in aqueous alkaline condition. But high overpotential even when the most active electrocatalyst, platinum, is used and rapid poisoning by strongly adsorbed N species inhibit the practical application. To deal with these problems, there are a lot of on-going researches with various methods and perspectives.

In this study, we investigated the effect of alkali metal cations on electrochemical AOR on polycrystalline platinum electrode. With same concentration but different alkali metal cations, measured the activity of platinum was different for the AOR peak (K+ > Na+ > Li+ ≈ Cs+). The reaction kinetics were also affected, supported by the electrochemical impedance spectroscopy and Tafel slope. Also, we checked that the alkali metal cation promotes the AOR by comparing the cyclic voltammetry results with and without the cation in ammonia solution. These kinds of cation effects are also demonstrated in other electrochemical reactions including the hydrogen evolution reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and oxygen evolution reaction. Mainly, there are two explanations i) the degree of interaction between cations and water structure and reaction intermediates at the interface, ii) the local electric field between electrode and hydrated cation in electric double layer. We will present and discuss the effect of alkali metal cations on the AOR in this point of view and competitive adsorption of water, proton, hydroxide and ammonia on the platinum surface in aqueous alkaline electrolyte.
(Invited) Evaluating Protocols for Real-Time Electrochemical CO2 Reduction Selectivity Measurements on Gold Rotating Ring Disk Electrodes
Authors: Kelly Maria , Wnuk Rachel A , Kas Recep , Teeter Glenn , Smith Wilson A
Published: December 2024

The electrocatalytic carbon dioxide reduction reaction (CO2RR) has the potential to convert carbon dioxide to higher value fuels and chemicals, offering a pathway for carbon neutral (or negative) synthesis of carbon monoxide, ethylene, and several other compounds. A common challenge for CO2RR research is driving the selective CO2RR over the competing hydrogen evolution reaction (HER). This key performance metric is quantified by the catalyst’s faradaic efficiency (FE): the number of electrons that go toward producing a specific product divided by the total number of electrons passed during electrolysis.

FE is often determined by gas and liquid chromatography. However, these methods have long response times (minutes to hours) and therefore prevent selectivity analysis in real-time. Instead, rotating ring disk electrodes (RRDE) have emerged as a rapid and sensitive method for quantitative CO2RR selectivity measurements with negligible time delays. To date, work has focused on a polycrystalline Au RRDE, especially for bench scale mechanistic studies. The Au disk electrode catalyzes both CO2RR and HER, while the concentric Au ring electrode senses the CO produced at the disk and oxidizes it back to CO2. By comparing the ring and disk currents, FECO and FEHER can be determined using the subtraction method.

However, comparison across several works have reported a wide range for FECO values, 60-83%, despite identical conditions: CO2 saturated 0.1 M NaHCO3 (pH = 6.8), Edisk
= -0.6 V vs RHE, and rotation at 2500 rpm [A. Goyal, et al., J. Am. Chem. Soc., 142, 4154–4161 (2020); R. E. Vos and M. T. M. Koper, ChemElectroChem, 9, e202200239 (2022)]. This work investigates the possible causes of this poor reproducibility in RRDE selectivity measurements by comparing protocols with different electrochemical methods, reagent purities, and glassware cleaning procedures. Most notably, we observed rapid loss of selectivity toward CO production during chronoamperometry measurements. Lastly, we propose operational bounds for RRDE selectivity measurements on Au under CO2RR conditions and provide our perspective on next steps for developing this into a robust analytical technique.
Scalable Synthesis of AgCl-Derived Ag Structures for Electrochemical CO2 Reduction
Authors: Chae Younghyun , Won Da Hye
Published: December 2024

Electrochemical CO2 reduction reaction (CO2RR) has the potential to serve as a competent technology capable of reducing the CO2 levels in the atmosphere while utilizing renewable energy. The CO generated from the CO2RR forms a component of syngas (CO/H2), which is highly demanded in the market and industry, recognized for its value as a chemical feedstock. However, to achieve an industrial-level current density, improvement in the CO2-to-CO catalyst is necessary. Au, Ag, and Zn exhibit high CO selectivity in the CO2RR due to their low CO desorption energy barrier and poor hydrogen binding energy, showing over 90% FE of CO. Particularly, Ag is considered a promising catalyst due to its high durability, selectivity, and moderate price. However, it fails to suppress HER at high potential and current regions, limiting the incretion in CO current density.

In this study, we developed a scalable AgCl nanocube catalyst for the CO2RR using a sonochemistry-based method. The AgCl nanocube achieved a CO current density of over 400 mA cm-2 in a 0.1 M KHCO3 electrolyte using an MEA cell. AgCl releases Cl and forms Ag surface through an electrochemical reduction process, resulting in AgCl-derived Ag catalysts. This AgCl-derived surface possesses high porosity, enhancing CO2 mass transfer, and promote CO2 adsorption through charged surfaces, leading to high CO current density. The uniform AgCl nanocube catalyst, which can be synthesized on a gram scale under mild conditions, offers cost-effective and rapid catalyst supply. During the reduction process, the AgCl nanocubes break into smaller particles, resulting in an AgCl-derived Ag catalyst with an increased surface area. Surface spectroscopic analysis revealed enhanced CO2 adsorption and the presence of Cl remaining on the catalyst surface. As a result, the AgCl nanocube successfully suppressed HER at high potential regions, maintaining a high level of CO selectivity, thereby increasing the productivity of CO2-to-CO electroreduction. A rapid and scalable synthetic method for nanoparticle that simultaneously obtains a reagent (Cl) that enhances the reaction and a CO2RR catalyst (Ag) could provide insights for future catalyst development.
Structure Sensitivity and Catalyst Restructuring for CO2 Electro-Reduction on Copper
Authors: Cheng Dongfang , Nguyen Khanh-Ly , Heyde Markus , Roldan Cuenya Beatriz , Alexandrova Anastassia N , Sautet Philippe
Published: December 2024

Cu is the most promising metal catalyst for CO2 electroreduction (CO2RR) to multi-carbon products, but the structure sensitivity of the reaction and the stability versus restructuring of the catalyst surface under reaction conditions are still controversial. Here, atomic scale simulations of surface energies and reaction pathway kinetics supported by experimental evidence unveil that CO2RR does not take place on perfect planar Cu(111) and Cu(100) surfaces but rather on steps or kinks defects, and that these planar surfaces tend to restructure in reaction conditions to the active stepped surfaces. By combining basin hopping global sampling and grand canonical density functional theory, we show that the extremely low CO coverage on (111) and (100) surfaces, originating from sluggish CO2 conversion and unfavorable CO binding, limits the ability of these surfaces to reduce CO2 to multi-carbon products. Steps and kinks at surfaces, despite the lack of decrease in C-C coupling barriers on these sites, exhibit a significant increase in activity arising from beneficial CO2 activation and higher CO coverage. Notably, the square motifs adjacent to defects, not the defects themselves, are the active sites for CO2RR via synergistic effect. In addition, the strong binding of CO on defective sites acts as a thermodynamic driving force for the restructuring of planar surfaces to active stepped terminations under reactive conditions. We evaluate these mechanisms against experiments of CO2RR on UHV-prepared ultraclean Cu surfaces. Overall, our findings highlight the structural sensitivity in steering CO2RR and elucidate the origin of in situ restructuring of Cu catalysts during the reaction. We furthermore feature that the active sites for CO2RR are created under reaction conditions.
Detection of Essential Biomolecules Using Paper-Based Electrode Sensors
Authors: Tolino Tonya , Wilson Katelyn , Begay Makeiyla , Platero Joshua , Billey Wayant , Platero Justin , Plummer Dallen , Soundappan Thiagarajan
Published: December 2024

Electrochemical paper-based biosensors (EPBs) have emerged as promising tools for rapid and cost-effective detection of essential biomolecules. The Nano Electrochemical Analysis and Energy Storage (N.E.S.T.) Laboratory at the Navajo Technical University is currently developing paper-based electrodes to assess levels of essential biomolecules, such as dopamine—a neurotransmitter that is responsible for functions involving memory, motivation, and learning. Traditional methods for the electrochemical detection of biomolecules often rely on screen-printed electrodes which, though effective, pose limitations in terms of cost, environmental impact, and accessibility, especially for communities such as the Navajo Nation. In contrast to traditional electrodes, paper-based electrodes offer an innovative alternative for addesssing these challenges. The unique properties of paper substrates in the paper electrodes make them ideal platforms for sensor development, particularly in resource-limited settings.The porosity of paper essentially allows for enhanced electrochemical reactions which facilitate more sensitive and faster detection of biomolecules like dopamine. The degradability of paper materials also contrasts with the more persistent waste generated by traditional electrodes, aligning with increasing demands for eco-friendly technologies. Further, the ease of modification and functionalization of paper surfaces allows for the tailored detection of a wide range of biomolecules, such as uric acid, glucose, and ascorbic acid. This advantage makes the use of paper based electrodes highly versatile and adaptable to various health and diagnostic needs. In all, this research demonstrates that paper-based electrodes are capable of revolutionizing the field of biosensing by providing an economical, efficient, and environmentally sustainable alternative to traditional methods such as electrodes that are screen printed.
Development of a Low-Cost Electrochemical Sensor Based on Oxygen Plasma-Modified Plastic Chip Electrode for Detection of Cxcl-10 Biomarker
Authors: Luhar Sunil , Patel Kinjal Bajiravbhai , Srivastava Divesh Narayan , Sabri Ylias , Rane Ramkrishna , Ippolito Samuel
Published: December 2024

The development of low-cost electrochemical sensors is crucial for point-of-care diagnostics and biomedical research. In this study, we present a novel approach using an Oxygen Plasma-Modified Plastic Chip Electrode for the detection of the CXCl-10 biomarker. CXCl-10, or interferon-inducible protein-10 (IP-10), is a key chemokine involved in immune responses and inflammation regulation, secreted by various cell types in response to interferon-gamma (IFN-γ) stimulation. Elevated levels of CXCl-10 have been linked to autoimmune disorders, infectious diseases, and cancer. The proposed sensor utilizes oxygen plasma treatment to modify the surface of a plastic chip electrode, enhancing its sensitivity and specificity towards CXCl-10 detection. Scanning Electron Microscopy (SEM) analysis reveals significant surface modifications post-plasma treatment, optimizing receptor attachment and analyte capture. Electrochemical techniques such as Electrochemical Impedance Spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) are employed to confirm receptor attachment and assess sensor performance.

This low-cost electrochemical sensor demonstrates promising results for sensitive and selective detection of CXCl-10, offering potential applications in point-of-care diagnostics and biomedical research for various diseases associated with CXCl-10 dysregulation. The development of such sensors contributes to advancing affordable and accessible diagnostic tools for improved healthcare outcomes.
Recyclable Cardiac Biosensor Based on Light-Triggered Antibody Regeneration Method
Authors: Masaki Masaki , Akimoto Yosuke , Shetty Vivek
Published: December 2024

Introduction: The diagnostic utility of heart failure biomarkers, particularly Brain Natriuretic Peptide (BNP), is well-documented. Yet, the clinical translation of BNP for tracking the progression of heart failure and assessing the therapeutic efficacy of drugs requires advancements in wearable sensor technology. Traditional antigen-antibody reaction-based biosensors, while effective, are hampered by the need for frequent reagent replenishment due to antibody regeneration challenges. We introduce a novel method employing laser irradiation to modulate pH levels, facilitating antibody regeneration and enabling the development of a wearable BNP sensor.

Methodology: Our approach utilizes a photoacid (Hydroxypyrene Trisulfonic Acid or HPTS) immobilized around the capture antibody of a sensor. Irradiating the sample with visible light for seconds induces HPTS to acidify the local environment, dissociating the bound antigens and regenerating the antibodies for reuse. The biosensor design incorporates: (a) a stainless-steel mesh substrate with gold vapor-deposited on the surface (gold mesh substrate); (b) an anti-BNP antibody immobilized on the substrate via a self-assembled monolayer; (c) HPTS immobilized on the gold mesh substrate; (d) a chamber containing the gold mesh substrate for immunoreaction; (e) a photomultiplier tube for signal detection. We validated this methodology by measuring pH changes in a 1 mL HPTS solution irradiated with a 50 mW, 405 nm laser for 5 minutes. Subsequently, a calibration curve for the BNP immunosensor was established using BNP standards (0.1 - 100 pg/mL). Finally, the light-triggered regeneration method was employed to dissociate BNP from the anti-BNP antibody.

Results: Laser irradiation triggered a decrease in HPTS solution pH, which rapidly returned to its baseline upon cessation of irradiation. This phenomenon was repeatable up to three times. The sensor captured BNP from a 50 µL sample via anti-BNP antibody interaction. Subsequent introduction of enzyme-labeled detection antibody formed a BNP sandwich complex. Luminescent substrate addition allowed for luminescence intensity (I) measurement at 450 nm. The resulting calibration curve fit the equation: I = 2980 ln (BNP) + 19713 (R2 = 0.86). The gold mesh substrate enabled visible light to penetrate the reaction area, facilitating detection by the photomultiplier tube. Finally, laser irradiation in the presence of 5 mM HPTS dissociated the antigen (BNP).

Conclusion: We present a novel laser-based method for antibody regeneration in biosensors, facilitating the realization of wearable devices for continuous heart failure monitoring. Overcoming the limitations of traditional biosensor reagent replenishment, our technology paves the way for advanced heart failure management tools, potentially transforming diagnostic and therapeutic strategies in cardiovascular medicine.

Figure 1
A Miniature Biosensor Based on Microbial Fuel Cell for Hexavalent Chromium in Wastewater
Authors: Wang Chin-Tsan , Li I-Ting , Jang Jer-Huan
Published: December 2024

Hexavalent chromium is considered as a human carcinogen due to its mutagenic and teratogenic properties, which can cause severe birth defects. Microbial Fuel Cell (MFC) is a promising power generation device for sustainable energy. The application of MFC is limited due to low power generation. In the present study, a miniature biosensor based on microbial fuel cell has been designed and assembled for detecting hexavalent chromium in wastewater. The miniature biosensor can generate power for sustaining operation. The power provided by the biosensor has been studied in the present investigation. Besides, both conductive silver glue and carbon cloth are employed as the anode for the biosensor. Electrochemical analyses for the above materials are conducted for the biosensor in detecting hexavalent chromium in the anode chamber. It is found that the maximum voltage can reach up to 518.17 mV and the power density of 1,075 mW/cm2 can be achieved with carbon cloth as the anode electrode using an external resistance of 1000W. It is also measured that a higher limiting current density can reach up to 0.015 mA/cm2 with conductive silver glue as the anode electrode. Furthermore, the voltage output of the biosensor decreased severely with the addition of hexavalent chromium into the wastewater. In addition, the recovery time for the biosensor is much shorter than those in previous studies. It is concluded that the biosensor possesses the potential of simultaneous detection of hexavalent chromium and electricity generation, leading to a new era of autosensing applications in the environment as well as smart powering devices.
Modification of rGO/ZIF-68 Based on Molecularly Imprinted Polymer Electrochemical Sensor for Detection of Acetamiprid
Authors: Mutlu Esma , Akyuz Duygu
Published: December 2024

Molecular imprinting (MIP) is one of the most efficient strategies used to provide recognition materials with continuous good selectivity, commonly employed in electrochemical sensors as recognition elements or modifier agents[1]. In this study, a highly sensitive Molecularly Imprinted Polymer (MIP) sensor was developed and successfully utilized for acetamiprid recognition. The MIP was decorated onto the surface of a zeolitic imidazolate framework (ZIF-68) and reduced graphene oxide (rGO) composite modified with a glassy carbon electrode (GCE) to fabricate the GCE/rGO/ZIF-68/MIP electrode. Spectroscopic and microscopic analyses such as XRD, FT-IR, XPS, and SEM were employed to evaluate the composition and morphology of the surface of the GCE/rGO/ZIF-68/MIP electrode. The electrochemical characterization of the electrodes was performed using cyclic voltammetry (CV), Squarewave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Additionally, different parameters influencing the sensitivity of GCE/rGO/ZIF-68/MIP, such as the percentage of rGO, template:monomer ratio, number of electropolymerization cycles, pH, extraction and incubation time were optimized. Under optimal conditions, the MIP sensor exhibited a wide linear range, low detection limit, as well as good reproducibility, stability, and selectivity, and it was successfully used for the determination of pesticide in real solutions. The sensor was applied to real samples for the acetamiprid pesticide, and successful recovery values were obtained.

Keywords: Electrochemical sensor; Molecularly imprinted polymer (MIP); Acetamiprid.
Self-Powered Device for Ultrasensitive Virus Detection Using Bimetallic Nanorod Co-Catalyst with Pt Tips
Authors: Ganganboina Akhilesh BABU
Published: December 2024

Self-powered photoelectrochemical (PEC) sensors have recently attracted a lot of attention in healthcare systems. An advancement and upgraded system is proposed for the ultrasensitive virus detection by self-powered PEC detection method. The detection signal is majorly based on the photo current response generated by novel electrocatalyst Co3O4-CdSe-CdS-Pt upon excitation with visible light. The proposed novel architecture of Co3O4-CdSe-CdS-Pt using hollow sphere, rod and quantum dot allowing to adjust Pt and Co3O4 position at a particular distance regulates the hole and electron recombination rate, improving the photo-catalytic performance. For the amplification of the detection signal, Co3O4-CdSe-CdS-Pt are encapsulated inside the liposomes. Conjugating the Co3O4-CdSe-CdS-Pt encapsulated vesicles with virus, followed by magnetic separation allows the variation of analytical signal in response to virus concentration. In brief a self-powered visible-light-driven device for rapid detection system for electrochemically sensitive viruses which can meet the emerging need for point of care diagnosis has been developed.
Ionic Conduction-Based Polycrystalline Oxide Radiation-Ionic Detection Effects
Authors: Defferriere Thomas , Gilgenbach Colin , Müller Matthias , Christian James F , LeBeau James , Tuller Harry L.
Published: December 2024

We recently demonstrated the ability to use photogenerated charge carriers to modulate the grain boundary resistance of a model polycrystalline oxygen solid electrolyte thin film (Gd-doped CeO2)[i]. These findings were inspired by the recognition that above bandgap light is well known to reduce band bending at interfaces by providing additional charge carriers which screen potential barriers. While our initial observations were limited to thin films due to the short absorption depths of above bandgap light, we then demonstrated that the same concept is applicable using gamma radiation, which is expected to have much deeper penetration depths than UV (nm vs. mm)[ii]. We showed that we could reproduce a similar optoionic effect in a bulk ceramic of Gd-doped CeO2 (1mm thick) and that reversible resistances modulation on the order of ~103 near room temperature could be obtained. In this talk, we discuss how our findings demonstrate new radiation detection concepts which rely on the modulation of ionic currents at grain boundaries in solid electrolytes instead of the collection of photogenerated charges carriers in single crystalline semiconductors. This paves the way for new, inexpensive, low-power, and miniaturizable solid-state detection devices that can operate in harsh environments. We will discuss our approaches for engineering impedance, radiation sensitivity and response time with the aim of achieving high-performance detection. This phenomenon is yet an example of the rapidly developing field of Opto-ionics, allowing for contactless triggering of ionic conduction in solids, and is expected to apply to other kinds of ion-conducting solid electrolytes (Li+ or H+), thus paving the way to a broad new class of radiation detecting materials.

The authors acknowledge support by the U.S. Department of Homeland Security, Countering Weapons of Mass Destruction Office, under awarded grant 22CWDARI00046. This support does not constitute an express or implied endorsement on the part of the Government.

[i] T. Defferriere, D. Klotz, J. C. Gonzalez-Rosillo, J. L. M. Rupp, and H. L. Tuller, Photo-Enhanced Ionic Conductivity Across Grain Boundaries in Polycrystalline Ceramics
, Nat. Mater. 21, 438-444 (2022) https://doi.org/10.1038/s41563-021-01181-2

[ii] T. Defferriere, A. S. H. A. Elwakeil, J. Rupp, J. Li and H. L. Tuller, Ionic Conduction Based Polycrystalline Oxide Gamma Ray Detection - Radiation-Ionic Effects. Adv. Mater., 2309253 (2024). https://doi.org/10.1002/adma.202309253
In-Situ Formation of Porosity and Metallic Particles on 2D Oxides Via Photothermal Effect Toward High Performance Formaldehyde Sensing
Authors: Ryu Ahrom , Nahm Sahn , Jang Ji-Soo , Choi Ji-Won
Published: December 2024

In recent years, the precise detection of Volatile Organic Compounds (VOCs) has become increasingly crucial owing to their substantial effects on both the environmental and human well-being. Within the spectrum of VOCs, formaldehyde (HCHO) stands out as a pollutant in indoor air and has been classified as a human carcinogen. Conventional gas sensor technologies have faced limitations in terms of their response speed, sensitivity, and ability to distinguish between difference gases. Consequently, the development of high-performance gas sensors with excellent selectivity, low operating temperature, fast response, and short recovery time has become imperative for effective detection and analysis of HCHO gas.

2D metal oxides have attracted significant attention across various scientific research fields due to their extraordinary physicochemical properties derived from unique crystal structures and surfaces. However, unfortunately, there are still challenges to achieving fast and sensitive chemical sensing using 2D metal oxides, primarily due to their limited surface porosity.

Here, a simple but powerful synthetic approach is proposed for producing highly porous and catalyst-loaded 2D metal oxides via a combination of 2D oxide exfoliation and flash-thermal shock (FTS). The molecular thin 2D Ti0.87O2 are simply synthesized by ion-exchange exfoliation and subsequent ultra-fast FTS (7.5 ms) process, resulting in simultaneous formation of uniform pores and catalytic Ti nanoparticles (NPs) on 2D Ti0.87O2 surface.

Ti nanoparticles (NPs) on surface of 2D Ti0.87O2. Density functional theory calculations and ex-situ TEM analysis reveal that the fast phase transformation of 2D Ti0.87O2 are key driving force of porosity and Ti NPs formation. Based on these features, the porous 2D Ti0.87O2 demonstrates an exceptional HCHO sensing performances, including outstanding reversibility and sensitivity even at room temperature.
Preparation of Platinum Nanoelectrodes Using Tapered Tungsten Probes and Their Application to a Single Cell Measurement
Authors: Yasuzawa Mikito , Sato Yusuke , Kido Takanori , Zhao Yumeng , Kurashina Masashi , Nagase Masao , Ueki Tomoyuki , Tabata Atsushi
Published: December 2024

Platinum nanoelectrodes, which the electroactive region is located on the tip, were prepared in two steps. First, an insulating film was formed on the tapered tungsten probe by electrodeposition coating using the cationic electrodeposition paint, and then platinum nanopillars with a diameter of about 200 nm were formed on the tip using Focused-Ion-Beam Chemical-Vapor-Deposition (FIB-CVD). The conditions for forming an insulating film on tungsten surface with low thickness and excellent insulation properties were investigated and were evaluated by electrochemical measurements and SEM observations, and an appropriate insulating film was successfully produced. After the formation of a platinum pillar on the tip of an insulating film-coated tungsten probe, a platinum nanoelectrode was obtained and confirmed to function as an electrode. Using automatic micro manipulation system, repeated insertion of platinum nanoelectrode into HeLa cell was attempted. The results showed that the insertion of platinum nanoelectrodes into HeLa cells appeared to be successful.
Catalytic Combustion Type H2 Gas Sensor Based on Cerium Oxide
Authors: Tamura Shinji , Sakurai Asuki , Imanaka Nobuhito
Published: December 2024

Hydrogen gas is the most promising clean energy source, but its use carries an explosion hazard (LEL: 4 vol%). Therefore, the real-time and accurate detection of H2 gas leakage at every emitting site is required with the compact sensor to prevent a critical accident. Among the compact H2 gas sensors proposed, the catalytic combustion type gas sensor using precious metal-loaded γ-Al2O3 such as Pt/Al2O3 as the catalyst is one of the sensors in practical use because of its long life and low-cost features. However, platinum is an expensive and scarce resource, and its use is desired to be reduced. Therefore, for the realization of the coming hydrogen society, the development of novel catalytic combustion type sensor using a noble-metal-free catalysts is important.

In this study, we focused on CeO2, Fe2O3, Co3O4, NiO as H2 oxidation catalyst and investigated the sensing performance of these metal oxides. In addition, we applied CeNbO4
+δ [1], having high oxide ion conductivity and redox property, as a promoter for CeO2 catalyst, and the H2 gas sensing performance of the sensor with 4 wt% CeO2/CeNbO4
+δcatalyst was investigated.

Among the sensors applied metal oxide (CeO2, Fe2O3, Co3O4, NiO), the sensor with CeO2 showed highest sensor output which is over 2 times higher than the sensors with other metal oxides. This is due to high specific surface area and low heat capacity of CeO2. Although the sensor using CeO2 showed good sensing performance, quantitative detection of H2 required a temperature of 105 °C or higher, which is still high for practical use.

To improve the H2 oxidation activity of CeO2, we applied CeNbO4
+δ as a promoter and the sensor with 4 wt% CeO2/CeNbO4
+δcatalyst. Figure 1(a) displays the response curves to H2 gas concentration change for the sensor applied 4 wt% CeO2/CeNbO4
+δ and CeO2. The sensor with 4 wt% CeO2/CeNbO4
+δcatalyst showed about 2.6 times higher sensor output compared to the sensor with only CeO2, indicating that the combination of CeNbO4
+δ improves H2 oxidation activity. Furthermore, the sensor with 4 wt% CeO2/CeNbO4
+δcatalyst was able to detect H2 gas concentration quantitatively even at 75 °C (Fig. 1(b)) with a 90% response time of about 14 seconds. The sensitivity to other gases such as carbon monoxide, methane, ethanol, and acetaldehyde was examined, and the sensor showed excellent selectivity for H2 at 75 °C.

[1] Y. Jin, Y. Quan, J. Liu, C. Qui, P. Pan, B. Shan, H. Luo, and P. Yang, J. Solid State Chem., 313, 123318 (2022).

Figure 1
Simultaneous Speciation of Inorganic Arsenic (III and V) Utilizing Gold-Manganese Oxide Nanoparticles Modified Electrochemical Sensors
Authors: Zhao Ke , Mao Canwei , Ding Ruiyu , Song Dean , Ge Liya , Lisak Grzegorz
Published: December 2024

Inorganic arsenic exists primarily in two stable valence states: III and V, each exhibiting distinct toxicological characteristics[1, 2]. Precisely distinguishing between As(III) and As(V) is essential for accurate risk assessment and environmental monitoring. Traditionally, this speciation involves a combination of costly and bulky instruments such as high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS)[3]. In response to the need for more efficient methods, alternative approaches like voltammetry have been explored. Despite attempts using gold and manganese in voltammetric detection, simultaneous measurement of As(III) and As(V) has remained unresolved. This study introduces a novel nanocomposite with an Au-Mn ratio of 10:1 (m/m) to modify the surface of screen-printed carbon electrodes (SPCEs). These modified SPCEs were successfully utilized for simultaneous monitoring and speciation of inorganic arsenic via voltammetry during simulated wastewater treatment. The linear range spans from 0.2 to 2 mg·mL-1 (ppm), with limits of detection (LOD) recorded at 0.048 ppm for total arsenic and 0.07 ppm for As(III), respectively. Significantly, the performance and accuracy of the developed voltammetric sensors for the simultaneous detection of total arsenic, As(III), and As(V) were validated against the sophisticated HPLC coupled with triple quadrupole ICP-MS (HPLC-ICP-QQQ) method.

References:

Navarathna, C.M., et al., Removal of Arsenic(III) from water using magnetite precipitated onto Douglas fir biochar. Journal of Environmental Management, 2019. 250: p. 109429.

Wang, Y., et al., Review of arsenic speciation, toxicity and metabolism in microalgae. Reviews in Environmental Science and Bio/Technology, 2015. 14(3): p. 427-451.

Chen, M.-L., L.-Y. Ma, and X.-W. Chen, New procedures for arsenic speciation: A review. Talanta, 2014. 125: p. 78-86.

Figure 1