bluuebunny/crossref_metadata_2025 huggingface dataset:
Sr Migration and Gd-Ce-Zr Interdiffusion in Solid Oxide Cells Under Different Fabrication and Testing Conditions
Authors: Liu Tian , Karki Surendra B , Ryu Sangbong , Polikarpov Evgueni , Kaspar Tiffany , Olszta Matthew , Marina Olga A
Published: December 2024

This work aims to understand how solid oxide cell (SOC) fabrication methods and SOC operating conditions affect Sr migration into the yttria stabilized zirconia (YSZ) electrolyte through the rare-earth doped ceria barrier layer. Ni-YSZ electrode-supported SOCs and coupons were fabricated using (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ-Gd0.1Ce0.9O2-δ (LSCF-GDC) oxygen electrode and GDC or samaria-doped ceria (SDC) barrier layer. Barrier layers were either screen printed and sintered to YSZ electrolyte layer at 1260 °C for 2h, or deposited using thin film deposition techniques such as PLD, electron beam and sputtering. LSCF-GDC electrode layer was sintered onto the GDC barrier at different temperatures from 950 to 1100°C for 2h to determine the effect of firing temperature and barrier layer thickness on Sr migration. Several SOCs were tested at 750°C in a wide range of operating conditions, both in SOFC and SOEC mode, for up to 12,000 hours. The GDC/YSZ interfaces in coupons and SOCs were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Sr-Zr rich phase formation at GDC/YSZ interface was observed in coupons with LSCF-GDC sintered at 1100°C, but not in the other coupons sintered below 1100°C, unless the barrier layer was too thin and porous. Furthermore, no Sr migration into YSZ was observed in SOECs with varying testing time from 0 h to12,000 h. In addition, Gd and Ce diffusion into YSZ occurred when GDC was fired at 1260°C, but not in cells with GDC deposited using thin film techniques without additional high temperature firing. No significant difference was noted in the GDC-YSZ interdiffusion layer growth after SOC testing for 1,000-12,000 h. Aberration-corrected scanning transmission electron microscopy (STEM) was involved to identify the composition and crystal structure of the Sr-Zr rich phase, which was demonstrated to be SrZrO3 phase. After the long-term SOC tests, no SrZrO3 phase or Sr migration through GDC grain boundaries was observed in cells with 5-7 microns thick porous GDC barrier. This presentation will demonstrate how optimization of fabrication conditions, thermal treatment and fabrication techniques, could mitigate the formation of the insulating SrZrO3 phase.
(Invited) A Statistical Model of Thermal Ionization of Excited Ce Ions in YAG
Authors: Collins John , Mishra Kailash C
Published: December 2024

In this talk we present a statistical model for quantifying the thermal ionization process of an excited impurity ion in a level just below the conduction band of the host while the impurity ion is under constant excitation. YAG:Ce is used as an example. We assume that under constant pumping of the Ce3+ ion into the 5d1 with a blue LED, a condition of thermal and diffusive equilibrium will exist between the conduction electrons and the electrons in the excited 5d1 level of Ce3+ ion. Using the Gibbs sum, we calculate the probability for an excited Ce3+ ion to be thermally ionized, leading to an electron in the conduction band. The density of conduction electrons is then calculated over a wide range of temperatures and excitation densities. The observed quenching of emission at high temperature in Ce-doped YAG with low Ce concentrations is also investigated within this model. It is shown that the experimentally-observed nonradiative losses in this phosphor can be reasonably simulated assuming losses occur via nonradiative decay from the conduction band to the Ce4+ ground state.
A Statistical Interpretation of Thermoluminescence
Authors: Collins John , Mishra Kailash C
Published: December 2024

In this talk we will discuss thermoluminescence-related processes using methods of statistical mechanics. With the assumption of thermal and diffusive equilibrium between the traps and the conduction electrons, we calculate the trap ionization probabilities over a wide temperature range and for traps at a variety of trap depths. These ionization probability vs. temperature curves show the expected behavior, with trap ionization increasing with increasing temperature. Using the ionization curves, it will be shown that one can reproduce, with good accuracy, the peak positions fitting of the glow curves of five traps observed in YAG:Ce.1 We find the position and shape of the glow curves depends on two factors, the trap depth and the conduction electron density. Also, the widths and shapes of the calculated glow curves have been examined in detail, and have been compared with band width expressions found in the literature2. The shapes of the calculated glow curves have been determined to be consistent with second order kinetics processes.

J. Ueda, P. Dorenbos, A. J. J. Bos, A. Meijerink, and S. Tanabe, J. Phys. Chem. C 2015, 119, 25003−25008, doi:10.1021/acs.jpcc.5b08828

R. Chen, J. Appl. Phys. 40, 570–585 (1969) doi.org/10.1063/1.1657437
Optical Properties and Application Development of Glass-Ceramics
Authors: Xu Xuhui , Yu Xue
Published: December 2024

Due to the excellent optical properties, glass ceramics are widely used in LED lighting, optical information storage, and other fields. However, the nucleation and growth process of nanocrystals in amorphous glass media is still unclear as to the key to the subjective control of optical properties and its application development. Herein, we propose a real-time in situ TEM imaging method to study the nanocrystal nucleation growth kinetics in amorphous glass media. The results reveal the missing mystery of the nucleation kinetics of amorphous nanoclusters. By directly observing the crystallization process of nanocrystals, the coexistence of the non-classical nucleation theory and the classical nucleation theory was confirmed, and the subjective regulation of the optical properties of glass-ceramics was realized. Based on the excellent optical properties of the optimized glass-ceramic, its application in up-conversion laser, laser refrigeration, short-wave shielding, and other fields has been further realized. Quantum dots with excellent scintillation performance are embedded in the glass to obtain a transparent and uniform composite material. The three-dimensional network structure of the glass ensures its scintillation performance while giving it excellent physical and chemical stability, realizing low-dose high-resolution X-ray imaging, and realizing Repairable after high-dose radiation damage. A trap center and an efficient luminescence center are constructed in the glass to realize mechanoluminescence, and the passive self-driven fiber stress sensing is realized by coupling the optical waveguide effect of the highly transparent glass fiber.
(Invited) Exploration of Pb-Free Metal Halide Crystal for Scintillator and Sensor Applications
Authors: Im Won Bin
Published: December 2024

Lead-free perovskite quantum dots (QD) and luminescent materials have garnered significant attention in the fields of optoelectronic and luminescent devices. These materials possess excellent optoelectronic properties and luminescent characteristics, making them highly promising for various applications. Recent advancements in artificial intelligence and machine learning (AI/ML) technologies have opened up new possibilities for predicting and exploring material properties. The application of AI/ML in the discovery and development of lead-free perovskite QD and luminescent materials has accelerated the research process and significantly contributed to the discovery of novel materials and improvement of existing ones. In this presentation, we introduce the latest research cases on the exploration and property prediction of lead-free perovskite QD and luminescent materials using AI/ML. We discuss the methods of material design and optimization through AI/ML and explore how these approaches contribute to the efficiency and performance enhancement of material development. Furthermore, we present the application results of lead-free perovskite QD and luminescent materials in the development of scintillator and sensors.
Exploration of Novel Crystal Structures of Narrow Band Phosphors By Deep Learning Generative Model
Authors: Abe Masaya , Takaba Hiromitsu
Published: December 2024

Recently, narrow band phosphors have been developed and are expected to be used in the display field due to their excellent luminescence with high color purity. However, the number of developed narrow-band phosphors is limited, and it takes a lot of effort and time to develop new phosphors through trial-and-error experiments. In this study, we constructed a generative model with an ingenious method for calculating crystal structure features, and attempted to search for new Eu-activated narrow-band phosphors by learning from the crystal structure database. As a search method, we used the Fourier-Transformed Crystal Properties-variational autoencoder (FTCP-VAE), which was trained on 38,657 inorganic crystal structures in the Materials Project database, to construct the latent space. The crystal structure was then generated by specifying arbitrary coordinates for the constructed latent space. The band distribution and emission wavelength were predicted by the regression model constructed from the measured data, and a promising crystal structure as a narrow-band phosphor was explored. As a result, 11 promising crystal structures of Eu2+-activated oxide phosphors were proposed. In this conference, we will present the detailed screening method of FTCP-VAE and obtained crystal structures.

Figure 1
Phosphor Technology for Display Applications
Authors: Song Younghyun , Choi SeungHee , Jeon Sie Wook , Jang InSeok , Jeong Ho-Jung
Published: December 2024

Since its opening in 2001, the Korea Photonics Technology Institute has been a specialized in the optical technology field. We are leading the lighting industry market and technology through research and development for various uses of light, including the defense field, and technical support for small and medium-sized companies.

In particular, the Korea Photonics Technology Institute's Inorganic Light-Emitting Display Research Center is actively researching related fields to lead the future display market. At this PRiME 2024 conference, we aim to provide help to researchers in related fields under the topic of ‘Phosphor technology for displays applications.’

In particular, we would like to introduce ceramic phosphor converter technology for laser displays. We would like to introduce the applicability of laser displays through nano-phosphor synthesis technology, sintering technology, and optical analysis.

In this communication, we present the feasibility of phosphor technology. By carefully designing the phosphor, these phosphor materials are believed to lead to excellent candidates as luminescence materials for display applications.
Some Approaches for Theoretical Search of Novel Phosphor Materials Based on First-Principles Calculations and Machine Learning
Authors: Ogasawara Kazuyoshi
Published: December 2024

For theoretical search of novel rare earth (RE)-doped or transition metal (TM)-doped phosphor materials, it is important to optimize the combination of luminescent ions and host crystals. For this purpose, information on the structure-property relationships such as the structure-energy relationship is indispensable. Accordingly, prediction of the absorption and emission energies for hypothetical materials is essentially important.

In our group, we conduct research to obtain such information by three approaches. (1) Analysis of detailed electronic structures based on first-principles calculations, (2) Prediction of emission and absorption energies based on first-principles calculations and machine learning, (3) Creation of structure-property maps based on systematic first-principles calculations.

In this talk, these approaches will be explained in detail and some of our results will be also presented.
Prediction of 1Eg energies in Ni2+ in Crystals Based on Racah Parameters B and C By First-Principles Calculations and Machine Learning
Authors: Kobayashi Tomoki , Tanaka Shuma , Ogasawara Kazuyoshi
Published: December 2024

Recently, demand of infrared phosphors is increasing because they can be used not only for lighting applications such as night vision camera and plant growth but also in various fields such as biomarkers that emit light by binding to abnormal sites in living organisms. Since the Ni2+-doped phosphors are drawing attentions as potential infrared phosphors, analysis of multiplet energies and emission mechanism of Ni2+ in crystals is very important for the development of novel infrared phosphors. For Mn4+, Cr3+ and Ni2+ in crystals, Brik et al. analyzed a large amount of experimental data in literature and indicated the importance of the Racah parameter C in addition to B and proposed a new Nephelauxetic parameter. Considering their results, we have recently created prediction models of 2Eg levels of Mn4+ and Cr3+ in oxides and fluorides based on the Racah parameters B and C using machine learning.

For theoretical design of infrared phosphors, a similar prediction model for 1Eg level of Ni2+ would be useful. According to the Tanabe-Sugano diagram for the d8 configuration, the energy of 1Eg is almost independent of Δ/B which is a measure of the strength of the ligand field normalized by the Racah parameter B. Therefore, the energy of 1Eg seems to be determined by the Racah parameter B. However, as pointed out by Brik et al., in actual experimental values in literature, there are Ni2+-doped crystals which have different 1Eg energies despite having almost the same B values, indicating the necessity of consideration of the Racah parameter C as well. In this work, we created systematic model clusters for Ni2+ ions in crystals and performed first-principles calculations of the multiplet energies using the DV-Xα and DVME methods. Using these systematic data as the training data, predictive models of 1Eg based on the Racah parameters B and C were created by machine learning and the influence of these parameters on the multiplet energies was investigated in detail.
Circularly Polarized Light Emission-Active Two-Dimensional Perovskites Using Helical Nanofilament Network
Authors: Lee Jae-jin , Choi Suk-Won
Published: December 2024

We present an innovative strategy for fabricating circularly polarized light emission (CPLE)-active two-dimensional (2D) perovskites by integrating a chiral superstructure composed of helical nanofilaments (HNFs). 2D perovskites with CPLE are promising candidates for advanced materials and applications due to their excellent electronic properties, enhanced optical characteristics, and potential in spintronic devices and emerging quantum technologies. Our method imparts chirality to non-chiral 2D perovskites using a porous chiral nanotemplate made of HNFs. In this process, perovskite precursors are incorporated into the porous chiral nanotemplate, allowing the 2D perovskites to grow within the chiral superstructure. This fabrication method enables the introduction of CPLE-active properties through chiral supramolecular structures, eliminating the need for complex chemical synthesis or molecular design. The CPLE properties depend on the nanopore size within the helical nanofilament networks.
Integrated Photosynthetic Bioprocess through Aerobic-Autotrophic and Electro-Fermentation in Electrolyzer Via Cupriavidus Metallidurans CH34
Authors: Song Young Eun , Kim Changman , Panichc Justin , Dou Chang , Singer Steven , Sundstrom Eric
Published: December 2024

Phototrophic bacteria and algae are primarily responsible for photosynthesis in aerobic environments, directly harnessing light energy to convert CO2 into chemical energy. Artificial photosynthesis mimics this process through strategies like the solar-to-fuel cycle, chemically reducing CO2 into various chemicals. Electrochemical systems, leveraging photovoltaic cells, have been developed to facilitate the transmission of electrons and H2, generated from water electrolysis, to microbial catalysts for fuel production. Cupriavidus metallidurans CH34, a versatile facultative chemolithotrophic microbe, utilizes Fe-Ni hydrogenase for H2 dependency. This study delved into the aerobic-autotrophic growth of C. metallidurans under electro-fermentation conditions using a single electrolyzer setup. To demonstrate mimicking photosynthesis based on an electrolyzer, we developed a scalable all-in-one single electrolyzer and applied RppA protein expressed C. metallidurans CH34 strains to confirm malonyl-CoA level measurement. As a result, Single cylinder electrolyzer fermentation appeared to demonstrate the well autotrophic growth, and it produced the malonyl-CoA, which derived chemical as flaviolin was accumulated at 695.9 ± 66.1 mg/L
(Invited) Bringing Electrochemistry to Raman Spectroscopy Again with Unconventional Approach
Authors: Kang Mijeong , Ansah Iris Baffour , KIM Donghyeon
Published: December 2024

Since the landmark discovery of enhanced Raman scattering at electrochemically roughened metal surfaces in 1974 (Chem. Phys. Lett. 1974, 26, 163), electrochemistry has ushered in a new era of Raman spectroscopy. Although the Raman signal is highly specific to molecular species and thus has great potential as a practical tool for molecular identification, its low cross-section has presented a significant challenge. This challenge has been met by the employment of plasmonic nanomaterials, the origins of which can be found in the study reported in 1974. Metallic surface with nanostructure, such as the electrochemically roughened metal surface, has surface plasmon that can greatly amplify both the incident electromagnetic wave and the scattered electromagnetic wave, which is termed electromagnetic (EM) enhancement, resulting in enhanced Raman scattering. This surface-enhanced Raman scattering (SERS) has emerged as one of the most popular analytical tools, thanks to the extensive development of new plasmonic nanomaterials. In addition to this material-wise signal enhancement, an electrochemical method can enhance Raman scattering by inducing a resonance condition: a charge-transfer resonance by the electron transfer between metal and Raman-active molecule. For achieving this chemical (CM) enhancement, it is essential to ensure proper alignment of the Fermi level of metal, the energy level of molecular orbitals, and the energy of incident light, and the application of electrochemical potential to the metal can adjust the Fermi level to meet the resonance condition.

Here, we present a unique application of electrochemical processes that can induce both EM and CM enhancements. In the presence of a metal cation (i.e., a precursor of a plasmonic substance), a suitable electrode potential can generate a new plasmonic surface on the electrode. This process can enhance the Raman signal of the molecule adsorbed on the electrode prior to the potential application, via the EM enhancement mechanism. Since the newly formed plasmonic surface is retained even after the potential application is terminated, the continuation of EM enhancement is expected; however, the Raman signal is significantly reduced. In addition, the Raman enhancement observed during the potential application is mode-selective, which is one of the characteristics of CM enhancement. In combination, the electrochemical process involving a plasmonic metal precursor harnesses both EM and CM enhancements, yielding a great enhancement of the Raman signal. The mechanistic study of this platform and its applications will be presented in this talk.
(Invited) Binding of DNA Aptamers to Target Molecules in Hydrated Ionic Liquids
Authors: Fujita Kyoko , Ikebukuro Kazunori
Published: December 2024

DNA aptamers are single-stranded oligonucleotides that bind to target molecules with high affinity and specificity. These interactions are governed not only by nucleotide sequence recognition but also by the presence of higher-order structures. The binding affinity of aptamers to target molecules may depend on various intermolecular interactions, such as electrostatic, hydrophobic, and hydrogen bond interactions. Water molecules are expected to affect the interactions between these molecules, considering that hydrogen bonding is essential for the formation of higher-order structures of both the DNA aptamers and target molecules. Furthermore, it has been reported that water activity affects the stability of DNA structures. Understanding the effect of water molecules on the structures and interactions of aptamers is, therefore, important for their further application. We have previously proposed ionic liquids (ILs) as potential candidates for controlling the state of water molecules.

ILs are salts with melting points below 100 °C, and the solvent properties can be tuned to some extent by selecting the component ions. We have previously reported that the use of "hydrated ILs", in which the component ions are selected and a small amount of water is added, allows biomolecules such as proteins and nucleic acids to dissolve while maintaining their higher-order structure as in aqueous solution [1]. Furthermore, increased long-term and thermal stability of biomolecules have been reported after dissolution in hydrated ILs. When oligonucleotides forming quadruplex structure in buffer solution are dissolved in tuned hydrated IL, i.e., hydrated cholinium dihydrogen phosphate ([ch][dhp]), the original quadruplex structure is retained [2].

Since it was found that oligonucleotides retain its original structure in hydrated ILs, the interaction of DNA aptamers with its target molecules has been investigated. As a first consideration, a thrombin-binding aptamer with an antiparallel G4 structure, namely 15-mer thrombin-binding aptamer (15TBA) and two different vascular endothelial growth factor 165 (VEGF) binding aptamers with parallel G4 structures, namely V7t1 and 3R02 were used [3]. Hydrated [ch][dhp] allowed the effective dissolution of these DNA aptamers while maintaining their G4 structure and binding affinity to the target molecule. On the other hand, change in the topology of DNA aptamers and the binding affinity were suggested in hydrated [ch][dhp] depending on the water contents. At the presentation, it will present the possibility of electrochemical detection of the binding between G4 and target molecules both in buffer solution and in hydrated ILs.

Reference

K. Fujita, H. Ohno, Chem. Rec., 23, e202200282 (2023).

K. Fujita, H. Ohno, Chem. Commun., 48, 5751 (2012).

K. Fujitta, T. Honda, K. Tsukakoshi, H. Ohno, K. Ikebukuro, J. Mol. Liq.
366, 120175 (2022).
Measurement of Cerium with Tyrosine-Functionalized EF-Hand Loop Peptide Bio-Electrochemical Sensor
Authors: Asaei Sogol , Renner Julie N.
Published: December 2024

The detection of rare earth elements (REEs) holds significant importance in various practical applications, particularly in monitoring industrial waste streams and assessing environmental samples such as urine. EF-hand loop peptide sequences, known for their affinity to REE ions, present a promising avenue for developing user-friendly sensors to support these studies. This study focuses on modifying an EF-hand loop peptide to covalently bond to a gold electrode and incorporate tyrosine as an electrochemically active indicator of REE binding. It is anticipated that as REEs bind to the peptide, a conformational shift will occur, modulating the current exchange between the redox-active tyrosine moiety and the electrode surface.

Isothermal titration calorimetry and circular dichroism are employed to evaluate the binding of the modified sensing peptide to REEs, with cerium chosen as a model REE. Utilizing a quartz crystal microbalance and cyclic voltammetry, we demonstrate the binding of the designed peptide to cerium ions while immobilized on a gold surface. Tests conducted in artificial urine and potassium phosphate buffer, mimicking physiological conditions, reveal the sensor's efficacy in detecting cerium ions.

The binding affinity of the tyrosine-conjugated peptide to cerium ions in solution is presented by KD to be approximately 4 µM, while the gold-immobilized peptide exhibits an estimated KD for cerium ions of about 1.1 µM. The effectiveness of the redox-active sensing peptide is explored in an electrochemical sensing platform, where the peptide-modified biosensor, created through thiol binding onto gold working electrodes within a screen-printed sensor setup, shows a current response modulated by different concentrations of cerium.

The developed biosensor demonstrates good affinity and selectivity for cerium, as evidenced by calibration curves constructed within a biologically relevant range. Overall, this research introduces an innovative electrochemical biosensor capable of detecting REEs using cerium ions as a model. The combination of the electrochemical platform and the designed peptide aptamer allows for the selective detection of cerium in simple buffer solutions and artificial urine, with high affinity, at concentrations relevant to human health.
Thin-Shelled Hollow Mesoporous TiO2 Spheres with Less Tortuosity As Fast-Charging Anode
Authors: Hyeon Chang-Wan , Kim Chan Woo , Chun Sang-Eun
Published: December 2024

Titanium dioxide (TiO2), abundant in nature and possessing excellent longevity characteristics, is gaining attention as a next-generation anode material for Li-ion batteries. However, compact stacking of TiO6 octahedra induces repulsion between the inserted Li ions, reducing rate performance and achievable capacity. Herein, we propose a hollow mesoporous electrode composed of TiO2 nanoparticles under 30 nm to enhance the interface between the electrode and electrolyte, facilitating the Li-ion movement and promoting a shorter diffusion distance for the inserted Li-ions. Furthermore, the formation of hollow structures enabled Li ions to enter and exit both inside and outside the hollow shell, facilitating rapid charging and discharging characteristics.

To produce this hollow mesoporous structure, TiO2 nanoparticles smaller than 20 nm synthesized by a sol-gel process were deposited on a spherical carbon support, and the support was subsequently removed. In particular, the thickness of the hollow shell was controlled to minimize the diffusional path area within the electrode through which Li ions move. Thin TiO2 shells facilitate ion migration via a reduced tortuosity while minimizing isolated pore formation, allowing D
Li+
of 3.22×10-11 cm2 s-1 to be attained, 40 times higher than that of bulk-type TiO2. With its rapid Li ion diffusion rate and thin shell, the TiO2 anode exhibited the 70% highest rate capability (10 C vs. 1 C) and a capacity of 221 mAh g-1 at 0.5 C (Fig. 1). The facile Li-ion transport enables the insertion of 0.66 mol Li ions per mole of TiO2 at 0.5 C and 67% rate performance (10 C vs. 0.5 C). When evaluating the rate capability in actual LIBs, a full cell assembled with a LiFePO4 cathode showed a rate performance of 60% (2000 mA g-1 vs. 50 mA g-1), outperforming the 40% for commercial bulk-type TiO2 in a full cell. Hollow mesoporous TiO2 provided a potential anode for fast-charging Li-ion batteries as a thin mesoporous shell allows for rapid ion insertion and extraction with the extended interface of electrode/interface.

Figure 1
Expanding Horizons in Electrocatalytic Biomass Valorization for Sustainable Chemical Synthesis
Authors: Cha Hyun Gil
Published: December 2024

Electrocatalytic biomass valorization stands as a promising pathway toward achieving carbon neutrality by leveraging sustainable energy sources to convert biomass-derived feedstocks into valuable products. Yet, to fully harness this potential, it is imperative to surmount numerous challenges and explore specific avenues for further advancement. A pivotal aspect entails broadening the spectrum of electrocatalytic processes to encompass the production of diverse high-value compounds. This study is dedicated to the synthesis of economical and robust electrocatalysts, alongside the development of integrated technologies for producing high-value chemicals. Our investigation targets critical challenges encompassing electrocatalyst design, cost-effectiveness, durability, selectivity enhancement, yield optimization, and technological integration.
(Digital Presentation) Study of Hexylamine Adsorption on a Gold Electrode
Authors: Ostapenko Gennady I. , Kalashnikova Nina A.
Published: December 2024

The adsorption of hexylamine on a gold electrode in 1 M HClO4 in the presence of 0.1 M Fe2+ and 0.1 M Fe3+was studied by the impedance method. The presence of the Fe3+/Fe2+ redox couple makes it possible to reliably fix the equilibrium electrode potential. It is assumed that the effective electrode surface decreases during surfactant adsorption and the charge transfer resistance increases in proportion to the coverage of the electrode surface with the adsorbate1. Therefore, the oxidation-reduction reaction of iron inhibited here by surfactant adsorption.

In Figure 1, Nyquist diagrams are shown for solutions with different hexylamine contents. These curves are modeled satisfactorily by the equivalent circuit presented in Figure 2. Here RΩ is the electrolyte resistance, Rctis the charge transfer resistance, W is the Warburg diffusion impedance, CPE has the meaning of a frequency distributed double-layer capacitance.

It has been shown that the adsorption of hexylamine on gold is well described by the Dhar-Fleury-Huggens isotherm. Adsorption isotherm is plotted in Figure 3. The slope values are in good agreement with the theoretical unit slope as well. Extrapolation of the straight line to log cS = 0 gives the value of the adsorption constant Kad = ([15.8±5.0] L mol–1). The Gibbs free adsorption energy ΔGad = (–16.7±1.2) kJ mol–1. The relatively low adsorption free energy (less than –20 kJ mol–1) confirms the physical nature4 of hexylamine adsorption.

J.O’M. Bockris and A.K.N. Reddy, Modern Electrochemistry, Vol. 2, 2nd ed.; Kluwer Academic, Plenum Publishers, New York (2000).

G.I. Ostapenko and N.A. Kalashnikova, J. Electrochem. Soc.
169, 116502 (2022). https://doi.org/10.1149/1945-7111/ac9d07

J. Bastidas, J. Polo and E. Cano, J. Appl. Electrochem., 30, 1173 (2000). https://doi.org/10.1023/A:1004036430497.

E. Khamis, F. Bellucci, R. M. Latanision and E. S. H. El-Ashry, Corrosion
47, 677 (1991). https://doi.org/10.5006/1.3585307

Figure 1
Electrolytic Extraction of Transition Metals from Lithium-Ion Cathodes in Molten Hydroxide Salts
Authors: Lichtenstein Timothy , Gesualdi Jarrod , Moore Colin , Stariha Sarah
Published: December 2024

We have developed an electrometallurgical recycling process that uses low melting temperature molten hydroxide salts to produce metals from lithium-ion battery materials. Existing commercial recycling processes typically use high temperatures, require high-purity reagents, and use coke as a reductant, which makes the processes expensive and CO2-emissions heavy1. Molten hydroxide salts can lower the required temperatures and emissions needed for extraction of critical materials from spent lithium-ion batteries.

Molten hydroxide salts are water-tolerant, oxyanion-conducting, and can be used as electrolytes for electrochemical extractions2. This water tolerance is unique among molten salts and enables oxyanion-based electrochemical reactions through the Lux-Flood acid-base equilibrium:

2OH- ↔ H2O + O2- (1)

Where water is the oxoacid and accepts oxyanions to form the hydroxide ion. Here, we leverage the unique properties of molten hydroxide electrolytes and demonstrate a one pot, two-step electrochemical extraction of critical metals from battery cathode materials. In the first step, lithium-ion cathodes are electrochemically reduced to form soluble oxides in the hydroxide melt. In the second step, the solubilized materials are reduced onto a separate cathode and recovered as an alloy. We will discuss test results for both process steps to recover Ni, Mn, and Co metal from both fresh NMC 622 and used cathode material (black mass). The effect of process conditions such as moisture content and operating parameters on the chemistry will be discussed.

B. MAKUZA et al., “Pyrometallurgical options for recycling spent lithium-ion batteries: A comprehensive review,” J. Power Sources 491 February, 229622, Elsevier B.V. (2021); https://doi.org/10.1016/j.jpowsour.2021.229622.

E. GÜRBÜZ et al., “Significance of Molten Hydroxides With or Without Molten Carbonates in High-Temperature Electrochemical Devices,” Front. Energy Res. 9 April, 1 (2021); https://doi.org/10.3389/fenrg.2021.666165.
Evaluating the Transport Behavior of Molten Salt Electrorefining Cells Using Simulations
Authors: Banks Dakota Scott , Tree Douglas R
Published: December 2024

Electrorefining, a fundamental process in electrochemistry, has seen broad use since its discovery more than a century ago. In the intervening time, the area was studied to the point that many saw the discipline as a solved problem and research in the area waned. However, recent developments, such as the introduction of molten salt systems and the need for refining of metals unsuitable for traditional solvents has revitalized interest in this field. One particular area of interest is the purification of actinide and lanthanide metals, especially from spent nuclear fuel. In addition to experimental work, researchers have sought to model these systems using computer simulations, yet the majority of these models are either specific to a single cell or reliant on simplifying assumptions, particularly concerning mass transport phenomena. Specifically, we hypothesize that assumptions related to migration, forced convection, diffusivities and activity coefficients can significantly impact the accuracy of these simulations. We have created a model for both operation and characterization of molten salt electrorefining cells that addresses these assumptions and in this talk we will discuss our efforts to construct and validate this model.
Hydroformylation of Alkenes by Supported Ionic Liquid Phase (SILP) Catalysis
Authors: Fehrmann Rasmus , Riisager Anders , Garcia-Suarez Eduardo Jose , Thang Le Minh
Published: December 2024

Hydroformylation of olefins forms aldehydes which are valuable final products as well as intermediates in synthesizing bulk chemicals like alcohols, amines, and esters with a yearly world production of about 12 Mt. Industrial hydroformylation processes are essentially homogeneously catalyzed systems with an economic incitement for improvement by easy separation of products and reuse of catalysts, high reactivity and selectivity by using new catalysts, novel processes and alternative methodologies.

One such potential candidate for an alternative catalyst is a Supported Ionic Liquid- Phase (SILP) catalyst comprising “heterogenized” homogeneous ionic liquid (IL) catalyst systems on a porous support. Such catalysts make it possible to apply the much preferred fixed bed continuous flow process design which overcomes the troublesome and energy demanding separation of the products from the reaction mixture obtained in the traditional homogenous batch process.In our previous and very recent studies [1-2], we have prepared SILP catalysts containing immobilized Rh-complexes of TPPTS-Cs3 in 1-butyl-3-methylimidazolium octylsulfate ([BMIM][n-C8H17OSO3]) on SiO2 support and investigated the influence of IL loading on the catalytic activity. The influence of other supports : SBA-15, MCM-41, Al2O3, ZrO2 and TiO2 has also been studied and the catalytic activity compared to the SiO2 SILP catalyst. Finaly we will report on a comparison on the catalytic activity of the SiO2 SILP catalyst by use of the ligand precurser TPPTS-Cs3 and the much cheaper TPPTS-Na3 salt.

References.

H. N. T. Ha, D. T. Duc, T. V. Dao, M. T. Le, A. Riisager, R. Fehrmann. Catal. Commun. 25, 136-141 (2012)

Nguyen, V. C., Do, V. H., Truong, D. D., Pham, T. T., Dinh, P. K., Vu, T. L., Garcia-Suarez, E. J., Riisager, A., Fehrmann, R., Le, M. T. Res. Chem. Int..49, 6, 2383-2398 (2023).
Enhancement of Oxygen Reduction Reaction Activity of Pt By Tuning Its D-band Center Via Transition Metal Oxide Support Interactions
Authors: Matsumoto Futoshi , Matsumura Tamaki , Fukunishi Mika
Published: December 2024

The enhancement of the oxygen reduction reaction (ORR) activity of platinum nanoparticles (Pt NPs) using transition metal oxide (MOx, M = Ti, Nb, Ta, W, Y and Zr) supports has been examined. In order to enable the use of transition metal oxides having low electric conductivity as supports, the Pt NPs were formed on thin transition metal oxides formed on conducting cup-stacked carbon nanotubes (CSCNTs). Metal oxide composites (M1M2Ox) prepared from two types of transition metal (M1M2: TiNb, NbTa and TaW) precursors were also used as supports. Pt NPs were photodeposited on MOx/CSCNTs and M1M2Ox/CSCNTs supports, resulting in MOx/CSCNTs and M1M2Ox/CSCNTs-supported Pt NPs catalysts (abbreviated as Pt/MOx/CSCNTs and Pt/M1M2Ox/CSCNTs). Their ORR activities in 0.1 M HClO4 aqueous solution were found to significantly depend on the atomic ratio of M1 and M2 in M1M2Ox as well as the type of metal oxide support. A “volcano-type” dependence of the ORR activity (represented as current density, mass activity and specific activity at 0.9 V vs. RHE) on the Pt d-band center, relative to the Fermi level, was obtained in a series of the Pt/MOx/CSCNTs and Pt/M1M2Ox/CSCNTs catalysts. It was found that the d-band center values (ranging from -3.83 to -3.42 eV) of the Pt deposited on MOx/CSCNTs and M1M2Ox/CSCNTs supports were lower than that (-3.39 eV) of the reference Pt/carbon black (CB), and that the Pt/TiNbOx (Ti:Nb = 1:6.6 in atomic ratio)/CSCNTs with a d-band center of -3.59 eV exhibited the maximum ORR activity, in agreement with the theoretical expectation that an ORR catalyst having a d-band center which is ca. 0.2 eV lower than that of Pt would have maximal ORR activity.
Field-Driven Reactivity and Adsorbate Reorientation on Electrode Surfaces
Authors: Warburton Robert
Published: December 2024

Electric fields affect interfacial structure and reactivity during electrochemical reactions. First-principles modeling can be used to elucidate the electrostatic potential profiles at the electrode–electrolyte interface, where these potentials can be highly inhomogeneous due to the presence of electrolyte ions and molecular adsorbates. In this presentation, periodic density functional theory (DFT) calculations are used to understand field-driven proton-coupled electron transfer reactivity and adsorbate reorientation at heterogeneous electrochemical interfaces. These calculations show that field-driven protonation of graphite-conjugated organic acids is enabled by continuous electronic conjugation between solid carbon electrodes and molecular surface sites. The redox potentials for proton-coupled electron transfer in these systems are predicted computationally, showing close agreement with experimental voltammetry measurements. Constant-potential DFT calculations are also used to understand the adsorption structure of L-cysteine on Au(111) electrode surfaces. Using a classical electrolyte model, these calculations elucidate the interactions between the cysteine adsorbate, the electrode surface, and the electrolyte ions at different applied potentials. These studies shed light on the effects of interfacial electric fields on electrochemical reactivity and adsorption geometries at solid–liquid electrochemical interfaces.
(Invited) Hydrogen Consortium: Advancements in Renewable Hydrogen Production
Authors: Dinh Huyen N
Published: December 2024

HydroGEN Energy Materials Network (EMN) is an U.S. Department of Energy (DOE) EERE Hydrogen and Fuel Cell Technologies Office (HFTO)-funded consortium that aims to accelerate the discovery and development of advanced water splitting materials (AWSM) for clean, low-cost hydrogen production. Materials innovations are key to enhancing performance, durability, and cost of hydrogen generation technologies.

HydroGEN is focused on low technology readiness level AWS technologies, including low- (alkaline exchanged membrane electrolysis) and high-temperature electrolysis (proton-conducting solid oxide electrolysis), photoelectrochecmical (PEC) and solar thermochemical (STCH) water splitting. This presentation will provide an overview of the HydroGEN EMN and technical highlights of a few lab-led and FOA-awarded R&D projects. HydroGEN continues to grow its community of industry, university, and national laboratories, forming a national innovation ecosystem focused on renewable hydrogen production.
(Invited) TiO2/MWCNT Composite Photoelectrodes for Water-Splitting Reaction Prepared Via Sol–Gel Electrophoretic Deposition
Authors: Matsunaga Mariko , Yu Yuhei
Published: December 2024

TiO2 is a representative photocatalyst used in practical applications. To improve its catalytic activity, an increase in the active surface area and electroconductivity is a promising approach. For this purpose, various composite structures have been investigated by many researchers. We investigated the composition of TiO2 with multi-walled carbon nanotubes (MWCNT) using various approaches. Recently, we have developed on environmentally-friendly sol–gel electrophoretic deposition (sol–gel EPD) to find the best composite structures of TiO2 and MWCNT as a photoanode.[1] Consequently, it was demonstrated that sol–gel EPD produces various film structures by changing the deposition conditions. For example, it was confirmed that the solute composition, that is, the proportion of TiO2 sol to MWCNT in the electrophoresis bath, linearly changed the thickness and Ti/C composition of the film. Excellent photoelectrochemical activity for the water-splitting reaction was confirmed with a TiO2 film by combining MWCNT in an appropriate manner via sol–gel EPD to improve the film conductivity and UV adsorption by TiO2. In this presentation, several conditions including solvent as well as solute composition of sol–gel EPD significantly influencing film structures of TiO2/MWCNT composite films will be introduced, and the as-prepared film structures that show the best photoelectrochemical activity are also discussed.

[1] Matsunaga, Y. Yu, K.Takahashi, “Photoelectrochemical Activity of TiO2/MWCNT Thin-Film Electrodes with Different Film Structures Prepared by Combining Electrophoretic Deposition and Sol–Gel Method,” Electrochemistry, 92(4), 047004 (2024).
(Invited) Modular Electrochemical Synthesis to Exploit Dynamic Electricity Markets and Recover Ammonia Electrochemically
Authors: Jin Song
Published: December 2024

Decarbonizing the power grid requires the widespread adoption of renewable (wind/solar) power sources but the unpredictable and intermittent nature of renewable power presents a grand challenge. This motivates the development of flexible electrochemical manufacturing technologies that can shift power demand/supply across space-time and scales. I will discuss new modular electrochemical synthesis strategies capable of providing demand flexibility at different timescales by participating in multiple electricity markets (day-ahead, real-time, and frequency regulation). Using a fast proton redox material, copper hexacyanoferrate, highly rate-mismatched modular electrochemical synthesis was achieved by decoupling half-reactions with different intrinsic kinetics to produce chemicals under drastically different reaction rates and timescales: the fast hydrogen evolution reaction and slow persulfate production reaction. Such a strategy enables flexible participation in different electricity markets and can reduce electricity cost of chemical production by 30-40%. I will also discuss how the electrochemical manufacturing of chemicals can be integrated with the electrochemical recovery of ammonium (and other nutrient) ions by using similar redox reservoir materials with ion selectivity. These results introduce innovative strategies for flexibly integrating modular electrochemical manufacturing processes various chemicals into the fluctuating power grid to achieve more economical and sustainable operations.
(Invited) Supported Design and Synthesis of Energy Materials Towards More Effective and Selective Approaches to Solar Fuels Production
Authors: Solarska Renata , Trinh Linh , Ramalingam Karthick , Bienkowski Krzysztof
Published: December 2024

Appropriate engineering of photoelectrodes is still emerging as a challenge in the search for efficient and stable materials for energy purposes. Hybrid CuO:Zn that owns small bandgap energy similar to that of pristine CuO and relatively high theoretical photocurrent still suffers from photo corrosion. Therefore, we tuned the electro-deposition of CuO:Zn nanostructures in such a way that the twisting of the coordination sphere or the Fermi level pinning of Zn ions could govern the photoelectrochemical properties, which allowed to double its apparent photocurrent compared to that of CuO. Implementing Zn ions enlarged the space-charge region, thus triggering the electron availability for the photolysis of water. Another cooper oxide, Cu2O is considered a suitable candidate for photoelectrochemical CO2 reduction to produce a variety of hydrocarbons, but its low selectivity, current density, and stability restrict further development. Herein, we also demonstrate a planar heterojunction of Cu2O@Zn5(OH)8Cl2 photocathode architecture for photo-electrochemical CO2 reduction. It provides C1, C3, C4 products (methane, propylene and butadiene) at 0.4 V vs RHE with current density of -1.2 mA/cm2 and shows excellent stability for 20 hours. The high selectivity is attributed to the synergetic effects between the zinc intermediate and Cu2O in sustaining the adsorption of CO* intermediates, enhancing the selectivity. These results provide new insights into the design of highly efficient Cu-based photo electrodes for enhancing the selectivity of photo-electrochemical CO2 reduction to produce high-value C3, and C4 products.
An Artificial Leaf That Generates Electricity: Coupling Photoelectro-Oxidation of Water to Bioelectro-Reduction of Oxygen
Authors: Kim Sung Yeol , Kim Giyong , Palmore G Tayhas
Published: December 2024

In this study, we demonstrate energy conversion in a device that couples photo- and bioelectrocatalysis. This device can be described as a photoelectrochemical biofuel cell where electricity is generated via photoelectrochemcial dioxygen evolution supplying substrate (i.e. dioxygen) for the oxydoreductase, laccase. This device mimics the photosynthetic process of leafs where the energy from sunlight is used to produce dioxygen and glucose, an energy-rich reaction product (electricity equivalent). The overall reaction of this system is the reversible interconversion of oxygen and water in a closed loop. This closed-loop device makes use of a photoanode of TiO2 (rutile, single crystal) that generates dioxygen via photoelectrolysis of water when illuminated, thereby providing an internal substrate (i.e., cathodic dioxygen fuel) for the oxidoreductase, laccase. The cathode of this system consists of an electrode coated with a conducting polymer matrix entrapping laccase and a redox mediator, 2,2'-azino-bis(3-ethylbenzothiaxoline-6-sulfonic acid (ABTS) (PAL-coated cathode), previously reported by our laboratory. The immobilization of the enzyme and its mediator eliminates the need for a separation membrane, allowing the anode and cathode to be located within the same compartment.