bluuebunny/crossref_metadata_2025_split 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).
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.
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.
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.
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