bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluoride Ion Conductor of Fluorosulfide with Double-Layer Honeycomb Structure
Authors: Oura Honoka , Tachibana Shintaro , Hirai Shinziro , Orikasa Yuki , Zhong Chengchao 
Published: December 2024

All-solid-state fluoride ion batteries (FIBs) have attracted considerable attention due to their high theoretical energy density and high safety compared with those of conventional lithium-ion batteries (LIBs) [1]. However, the practical application of FIB lacks suitable solid electrolyte with high ionic conductivity and wide electrochemical potential window at room temperature. In addition, most of the fluoride ionic conductors reported previously are limited to fluorides such as fluorite, tysonite-type, and perovskite-type structures [2]. Therefore, increasing the variations of crystal structures for fluoride ion conductors are expected.
Fluorosulfides containing S2− and F− with largely different ionic radii are ideal for creating anion-ordered structures and expected to create fluoride ion conductors not found in reported fluoride[3]. In this study, we synthesized rare-earth fluorosulfides LaM
2F3S2 (M = Ba, Sr) and measured their ionic conductivity. Powder samples were weighed in stoichiometric ratio under an Ar atmosphere and pulverized by mortar mixing. The pelleted sample was placed in a Ta container, vacuum sealed using a quartz tube, and then calcined. The obtained samples were structurally evaluated by XRD measurement. For the evaluation of conductivity by the AC impedance method, the obtained powder was formed by isostatic pressing, sintered again, and Au electrodes were deposited on both sides as sintered specimens.
In the crystal structure of these fluorosulfides, anion-ordered 2D crystal structures are formed, which cannot be achieved in a single anion compound. The F− conducting layer is a double-layer honeycomb structure, with F− conducting two-dimensionally via four-, six- and four-coordination sites. The conductivity at 100°C is in a order of 10-6 S cm-1, which is highest among mixed-anion compounds but is several orders of magnitude lower than previously reported single-anion compound. On the other hand, the activation energy was 0.50 eV, which is comparable to that of the fluorite-type structure Ba0.6La0.4F2.4. The material development of fluoride ion conductors using flurosulfide compounds is expected to increase crystal structure variations with fluoride-ion conduction pathways.

References:

A. Reddy, M. Fichtner, J. Mater. Chem, 21, 17059-17062(2011).

Motohashi, T. Nakamura, Y. Kimura, Y. Uchimoto, K. Amezawa, Solid State Ionics., 338, 113-120(2019).

Tachibana, C. Zhong, K. Ide, H. Yamasaki, T. Tojigamori, H. Miki, T. Kamiyama, K. Shimoda, Y. Orikasa, Chemistry of Materials
., 35, 4235-4242(2023)
The Effect of SOFC Flow Rate Conditions on the Composition of Lean Oxygen Gas Used in Trigeneration System
Authors: Inagaki Naoyasu , Shimada Iori , Osada Mitsumasa , Takahashi Nobuhide , Fukunaga Hiroshi 
Published: December 2024

Solid oxide fuel cell (SOFC) is attracting attention for its high efficiency and low environmental impact. By integrating them into cogeneration systems, which harness the waste heat produced during power generation, significant overall efficiency gains can be achieved. Trigeneration systems (TGS), which extend this concept by incorporating exhaust gases alongside cogeneration, hold promise for reducing overall cost and energy required for the process. In this study, TGS was considered to utilize the exhaust gas from the SOFC cathode as a lean oxygen gas. Conventionally, nitrogen used as lean oxygen gas is obtained through energy-intensive deep cooling separation of air, and the process requires significant cost and energy. They are expected to be reduced by using SOFC exhaust gas to obtain lean oxygen gas. However, employing SOFC in TGS requires consideration of the tradeoff between oxygen concentration and power density. Consequently, this study aims to elucidate the impact of operating SOFC at high oxygen utilization on power generation characteristics. The influence of flow conditions on power generation characteristics was examined through experimental investigations under integral reactor conditions, where air was supplied to the cathode at a small flow rate, and under differential reactor conditions, where gas with a different composition was supplied at a larger flow rate. Additionally, simulations of oxygen concentration distribution within the flow channel were conducted.
Under integral reactor conditions, power generation characteristics of the SOFC exhibited voltage drops in the low current density region at lower flow rates. To investigate variations in oxygen utilization under different flow conditions, concentration and current density distributions within the cell were obtained from numerical analysis using the finite volume method1). A 1-D model was established for analysis, considering mass balance of gas flow in the channel direction. The distribution was calculated by correlating current density with overvoltage and oxygen concentration, as determined from results obtained under differential reactor conditions. The analysis revealed that as flow rates decreased, current density diminished towards the cell outlet, and at lower flow rates, with slight current flow observed near the outlet, indicating little oxygen is consumed there. Consequently, optimizing operating conditions to minimize the portion of the system where oxygen consumption is low are required for effective utilization of SOFC in TGS.
Acknowledgement
This work was supported by F. C. C. Co.
References
1) Y. Inui et al., IEEJ Trans. PE, 123(1), 66 (2003)
Development of Cos-PANI Core-Shell Structure Catalyst for Oxygen Reduction Reaction in Alkaline
Authors: Jae Sang Lee , Jung Won Suk 
Published: December 2024

Anion exchange membrane fuel cells(AEMFCs) are a technology that generates electricity through environmentally friendly means by reacting hydrogen and oxygen, producing water as a byproduct. Unlike Polymer Electrolyte Membrane fuel cells(PEMFCs), AEMFCs utilize non-precious metal catalysts in an alkaline environment, promoting more stable reactions. They offer cost-effectiveness and environmentally superior advantages. However, there are still performance shortcomings, necessitating research to enhance the activity of non-precious metal catalysts.
In this study, we synthesized a non-precious metal catalyst using Cobalt sulfide(CoS) and the conductive polymer polyaniline(PANI), and conducted research to enhance its activity. The electrochemical and physicochemical characteristics of the catalyst were observed according to the synthesis temperature conditions of CoS, and the optimization of the synthesis temperature was conducted. Additionally, to protect the active sites, the ratio of the monomer aniline and the oxidant APS was optimized during the polymerization of PANI, resulting in a clustered structure rather than a fiber structure, for encapsulating CoS in a core-shell configuration.
Analysis of Binder Degradation By Measuring Fluorine Emission Rate in PEMFC MEA Made with Speek Membrane and Nafion Binder
Authors: Lee Mihwa , Yoo Donggeun , Park Kwonpil 
Published: December 2024

In fuel cell vehicles for large commercial vehicles that require high power, oxygen must be sufficiently transmitted through the binder to the catalyst surface in the catalyst layer of the stack, and the durability of the binder must be high. Although research is actively underway to improve the durability of binders, an in-situ durability evaluation method for binders has not yet been established.
In this study, a study was conducted to accelerate degradation of the catalyst layer using Nafion as a binder with hydrocarbon-based sPEEK membrane and measure the binder degradation rate (FER, Fluorine Emission Rate) in-situ. The binder degradation rate was measured by analyzing the fluorine ion concentration of the condensate while deteriorating the binder in the catalyst layer using the catalytic accelerated degradation protocol. Impedance as in-situ analysis method was measured, and the data was organized using DRT(Distribution of Relaxation Time) and WLR(Warburg-like Response) methods and then compared with FER. It was shown that binder durability can be analyzed by in-situ FER measurement, and it was confirmed that research to increase the binder degradation rate is necessary to improve analysis accuracy.
Plasma-Induced Oxygen Vacancy-Controlled CuOx/N,Se Co-Doped Porous Carbon for Boosted Nitrate Reduction to Green Ammonia
Authors: Maeng Junbeom , Jang Daehee , Ha Jungseub , Kim Won Bae 
Published: December 2024

Ammonia has recently emerged as a promising renewable energy carrier owing to its carbon-free nature and high energy density of 4.3 kW h kg−1. However, traditional industrial synthesis of ammonia via the Haber-Bosch process demands high temperatures (400–500°C) and pressures (100–200 atm), resulting in substantial energy consumption and greenhouse gas emissions. The electrochemical nitrate to ammonia reduction reaction (NO3RR) presents a viable alternative to the Haber-Bosch process, although its efficacy is hindered by low reaction performance, particularly due to competitive hydrogen evolution reactions (HER).
In this study, we successfully prepared oxygen vacancy-controlled copper oxide (CuOx) catalysts via a simple plasma treatment. These catalysts were supported on high surface area porous carbon supports co-doped with nitrogen and selenium species to enhance their electrochemical properties. Among these catalysts, the oxygen vacancy-increased CuOx catalyst supported on N,Se co-doped porous carbon (CuOx/NSePC) demonstrated the highest NO3RR performance, achieving a faradaic efficiency (FE) of 87.2% and a yield of 7.9 mg cm-2 h-1 for ammonia production. These results signify significant enhancements in FE and ammonia yield compared to the un-doped or oxygen vacancy-decreased catalysts. The observed high performance can be attributed to an increase in catalytic active sites facilitated by heteroatom doping and weakened N-O bonding strength, enhancing the adsorption of NO3
- ions on modulated oxygen vacancies.
Our findings underscore the importance of co-doping heteroatoms and regulating oxygen vacancies as key factors for enhancing NO3RR catalyst performance, offering valuable insights for effective catalyst design. This work presents a novel approach in the realm of electrochemical nitrate reduction for green ammonia production, providing a foundation for the development of high-efficiency metal oxide-based catalysts and extending their applicability to diverse electrochemical reactions

Figure 1
Formation of Atomically Thin Co Layer on Ru Nanoparticles through Surface Limited Redox Replacement of Underpotentially Deposited Zn
Authors: Suyama Kyota , Muramatsu Keisuke , Sugimoto Wataru 
Published: December 2024

In order to promote the widespread commercialization of polymer electrolyte fuel cells, highly active electrocatalysts are necessary to reduce the usage of scarce and expensive Pt electrocatalysts. Among various approaches, alloying with non-Pt metals and/or fabricating core-shell structures have been recognized as effective methods to optimize the electronic state of Pt and enhance catalytic activity while reducing Pt loading.1 One ideal catalyst design to maximize Pt utilization involves depositing atomic layers of Pt onto heterogeneous metal surfaces. We have prepared Ru-core@Pt-shell nanostructures by using underpotentially deposited (UPD) Cu on Ru nanostructures and subsequent replacement with Pt atomic layers (Surface Limited Redox Replacement; SLRR).2 In this study, we aimed to control the electronic state of Pt atomic layer on Ru by using a Co-interlayer; i.e. Ru-core@Co-interlayer@Pt-shell nanoparticles.
Since Co cannot be replaced with UPD-Cu, we investigated a synthetic route involving UPD of Zn followed by Co replacement through SLRR. Ru nanoparticles supported on carbon (Ru(np)/C) with particle sizes of approximately 1–3 nm was synthesized according to a previous literature.3 Cyclic voltammetry of Ru(np)/C in an electrolyte solution containing Zn ions was conducted to examine the UPD potential (–0.10 to 0.85 V vs. RHE, 20 mV s–1, pH 11.2). Reduction current was observed near 0 V vs. RHE in the cathodic scan. The deposition potential of Zn in a solution with pH 11.2 was –0.44 V vs. RHE, while the hydrogen evolution potential was 0 V vs. RHE. Therefore, the reduction current most likely originates from UPD of Zn and hydrogen evolution. In the anodic scan, a peak attributed to oxidation of underpotentially deposited Zn was observed near 0.25 V vs. RHE. Subsequently, the Zn deposition amount was calculated by stripping of Zn after maintaining the potential at –0.04 V. The amount corresponds to approximately 40–50% of the ECSA of Ru(np). This result supports the deposition of Zn as atomic layers via UPD. After Zn deposition, Co was deposited through SLRR by immersing the electrode in an aqueous solution containing Co ions. EDS analysis showed a presence of Co and decrease in relative Zn content to Ru compared to Ru(np)/C sample after Zn UPD. Thus, it is suggested that Ru-core@Co-shell nanoparticles were synthesized via Zn UPD.
References

V. Stamenkovic, B. S. Mun, K. J. J. Mayrhofer, P. N. Ross, N. M. Markovic, J. Rossmeisl, J. Greeley and J. K. Nørskov, Angew. Chem. Int. Ed., 45, 2897 (2006).

D. Takimoto, T. Ohnishi, J. Nutariya, Z. Shen, Y. Ayato, D. Mochizuki, A. Demortière, A. Boulineau and W. Sugimoto, J. Catal., 345, 207 (2017).

Y. Takasu, T. Fujiwara, Y. Murakami, K. Sasaki, M. Oguri, T. Asaki and W. Sugimoto, J. Electrochem. Soc., 147, 4421 (2000).

Figure 1
Operando Fluorescence Spectroscopy Setup for Radical Detection during Proton Exchange Membrane Water Electrolysis Operation
Authors: Winkelmann Leonard , De Arghyadeep , Meier Stefan , Wagner Maximilian , Löttert Lukas , Martschin Philipp , Maier Maximilian , Herrmann Yanik , Boehm Thomas , Thiele Simon 
Published: December 2024

In a world with an ever-increasing energy demand, efficient and durable energy conversion devices for renewable energy sources are of great importance. Proton exchange membrane water electrolyzers (PEMWEs) are among the industry-established systems for converting electricity into hydrogen as a chemical energy carrier. In these systems, the proton exchange membrane (PEM) has to separate the two evolved gases (H2 and O2). The degradation of this membrane during operation, e.g., membrane thinning, can lead to system failure due to electrical shorts or dangerous explosive gas mixtures of H2 in O2 [1]. Therefore, it is important to gain a detailed understanding of the membrane degradation mechanisms in order to develop suitable mitigation strategies and extend the device lifetime.

One possible cause of ionomer degradation is the evolution of reactive oxygen species (ROS), namely hydroxyl and hydroperoxyl radicals, during WE operation, causing main chain scission and leading to membrane thinning [2]. Due to the very short lifetime of these highly reactive species, direct detection within the PEM is challenging.
However, there is an indirect detection method possible that has already been applied to PEM fuel cells [3]: The membrane is infused with a radical-sensitive fluorescent dye and an optical probe is embedded within this dyed membrane [Fig.1]. This way, a fluorescence signal can be measured upon excitation with a suitable light source. With the membrane being exposed to ROS, the radicals attack the membrane as well as the dye molecules, which can be measured by a change in fluorescence intensity. This setup was adapted for the application in PEMWEs to measure the effect of various operating conditions of the cell on ROS production and, hence, to detect stressors for membrane degradation.

References

[1] Grigoriev, S. A., Dzhus, K. A., Bessarabov, D. G., & Millet, P. (2014). Failure of PEM water electrolysis cells: Case study involving anode dissolution and membrane thinning. International Journal of Hydrogen Energy, 39(35), 20440-20446.

[2] Zhang, Z., Han, Z., Testino, A., & Gubler, L. (2022). Platinum and Cerium-Zirconium Oxide Co-Doped Membrane for Mitigated H2 Crossover and Ionomer Degradation in PEWE. Journal of The Electrochemical Society, 169(10), 104501.

[3] Prabhakaran, V., Arges, C. G., & Ramani, V. (2012). Investigation of polymer electrolyte membrane chemical degradation and degradation mitigation using in situ fluorescence spectroscopy. Proceedings of the National Academy of Sciences, 109(4), 1029-1034.

Figure 1
Study on the Distribution of Platinum within Polymer Membrane during MEA Degradation in PEMFC
Authors: Yoo Donggeun , Oh Sohyeong , Jung Sunggi , Lee Junsub , Park Kwonpil 
Published: December 2024

The Pt/C added to the PEMFC polymer membrane serves as a gas barrier, facilitating the generation of water through the hydrogen and oxygen combustion reactions on the Pt surface within the membrane. As water is produced, Pt acts as an antioxidant, humidifying the membrane and preventing radical generation, thus enhancing performance and durability. Pt needs to be closely spaced between particles to act as a radical scavenger, and it has been reported that under different operating and degradation conditions, the size and distribution of Pt within the membrane vary. Therefore, this experiment aimed to observe the movement and distribution changes of Pt/C within the membrane during accelerated degradation.
In this experiment, Pt/C was added to the cathode ionomer layer to manufacture a reinforced membrane with a thickness of 15 μm. The MEA was produced by hot pressing Pt/C electrodes onto the reinforced membrane, with a Pt loading of 0.4 mg/cm2. After assembling the MEA into a cell, chemical durability evaluations of the electrode catalyst, catalyst support, and membrane were conducted. The cross-sections of the MEA before and after degradation were analyzed using SEM and TEM to confirm the distribution of Pt within the membrane.
After chemical degradation of the polymer membrane, Pt/C within the membrane remained stationary, but dissolved/deposited Pt within the electrode layer migrated into the membrane, indicating a closer proximity between Pt/C and Pt. During catalyst and catalyst support degradation, movement of Pt/C within the membrane and changes in its distribution were observed.
Enhanced Electrochemical Hydrogenation of Aromatic Hydrocarbons in Alkaline Electrolytes
Authors: Markunas Brianna , Snyder Joshua David 
Published: December 2024

Thermal chemical hydrogenation (TCH) is a key reaction for converting petroleum and biomass feedstocks to value-added fuels and chemicals. Electrochemical hydrogenation (ECH) is a mild alternative where applied potential drives the hydrogenation of hydrocarbons with protons sourced from the aqueous electrolyte near ambient conditions. Lignocellulose is an abundant renewable feedstock comprised of complex phenolic compounds that can be valorized via ECH. Phenol and benzaldehyde are simple model compounds for lignocellulose that have been the focus of recent ECH studies. When both phenol and benzaldehyde are present as reactants, phenol has been shown to act as a proton shuttle, enhancing benzaldehyde ECH rates but with negligible phenol turnover. [1] The study of the role of electrolyte on the ECH of these aromatic hydrocarbons is limited to a few buffer systems (typically acetate, phosphate, or sulfate) and in a pH range of 1-5. However, it well-known that the competing hydrogen evolution reaction (HER) kinetics are slower in base, and that molecules like phenol dissociate within a pH range of 1-14. Thus, a complete understanding of the role of electrolyte pH, especially in alkaline media where slowed HER rates may improve faradaic efficiency of ECH, is desirable.
In this work, we show using cyclic voltammetry and chronoamperometry with product analysis that there are contrasting pH trends between platinum and rhodium for phenol ECH, with the highest ECH rates on platinum at pH 1 and the highest ECH rates on rhodium at pH 10. In-situ electrochemical FTIR and electrochemical impedance spectroscopy reveal that this is the result of differences in hydrogen adsorption kinetics, phenol/H coverage, and competition with HER between the two metals. For phenol ECH on rhodium, we show that pH-driven changes dictate the balance between a hydrogen atom transfer (LH) mechanism and a phenol-mediated proton coupled electron transfer mechanism. We also discuss phenol’s role as a proton shuttle towards benzaldehyde hydrogenation in alkaline pH, near the pka of phenol. With this insight, we show that the unique properties of rhodium and strategic tuning of the acid-base chemistry of phenol and the electrolyte can be utilized to yield elevated ECH rates with enhanced FE through slowed HER.
[1] Sanyal, U., et al., Hydrogen Bonding Enhances the Electrochemical Hydrogenation of Benzaldehyde in the Aqueous Phase. Angew Chem Int Ed
2021, 60 (1), 290–296. https://doi.org/10.1002/anie.202008178.
One Scale to Rule them All – A Unified Redox Scale
Authors: Kienzle Timo , Oppermann Tanja , Radtke Valentin , Krossing Ingo 
Published: December 2024

Thermodynamic quantities of single ions, such as the proton activity (i.e. pH values) or single ion Gibbs solvation energies (i.e. redox potential values), are widely used in chemistry and related sciences.[1] Thus, methods for the experimental determination of these values are of great interest. Our work focuses on the experimental determination of Gibbs transfer energies Δtrans
G(i, S1 → S2) of the ion i, between the different solvents S1 and S2, as the central values for the solvent independent, unified acidity scale pHabs
H2O and redox scale E
abs
H2O, and their two-dimensional combination, the Protoelectric Potential Map (PPM).[2] We established an 'ideal' ionic liquid salt bridge (ILSB) setup, using potential measurements between two electrochemical half cells (Fig. 1).[3] In this setup, the electroactive species is dissolved in different solvents, like water or acetonitrile, and the half-cells are connected by an ILSB. 'Ideal' regarding identical diffusion coefficients for both cation and anion of the ionic liquid to minimize liquid junction potentials at the phase boundaries.
Up to now, our research focused on solvents with high permittivity, like water or acetonitrile, utilizing the redox systems Ag+/Ag and Cl2/Cl−.[4] Within this contribution, we present the E
abs
H2O-scale extended by measured transfer energies in low permittivity solvents, like dichloromethane or fluorobenzene, which are not compatible with the previous setup due to the low solubility of the redox systems used. For this application the redox systems Ag+/Ag and Ferrocenium/Ferrocene (Fc+/Fc) were used. In this way, we can include several values measured by cyclic voltammetry.[5] The E
abs
H2O-scale gives the experimental chemist the possibility of a more straightforward synthesis design and the theoretical chemist values to benchmark his calculations.

REFERENCES

P. Hünenberger, M. Reif, Single-ion solvation. Experimental and theoretical approaches to elusive thermodynamic quantities, Royal Society of Chemistry, Cambridge, 2011.

V. Radtke, D. Himmel, K. Pütz, S. K. Goll, I. Krossing, Chem-Eur. J.
2014, 20, 4194.

a) V. Radtke, A. Ermantraut, D. Himmel, T. Koslowski, I. Leito, I. Krossing, Chem. Int. Ed.
2018, 130, 2368; b) A. Ermantraut, V. Radtke, N. Gebel, D. Himmel, T. Koslowski, I. Leito, I. Krossing, Angew. Chem. Int. Ed.
2018, 130, 2372.

a) V. Radtke, N. Gebel, D. Priester, A. Ermantraut, M. Bäuerle, D. Himmel, R. Stroh, T. Koslowski, I. Leito, I. Krossing, Eur. J.
2022, 28, e202200509.; b) V. Radtke, D. Priester, A. Heering, C. Müller, T. Koslowski, I. Leito, I. Krossing, Chem. Eur. J.
2023, 29, e202300609.

I. Krossing, C. Armbruster, M. Sellin, M. Seiler, T. Würz, F. Oesten, M. Schmucker, T. Sterbak, J. Fischer, V. Radtke et al., e-preprint DOI: 10.21203/rs.3.rs-3921217/v1.

Figure 1