bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Absorption Spectroscopy Studies of Ti-Mn Redox Flow Battery to Clarify the Redox Reaction
Authors: Asakura Daisuke , Hosono Eiji , Kitamura Miho , Horiba Koji , Magome Eisuke , Setoyama Hiroyuki , Kobayashi Eiichi , Yuzawa Hayato , Ohigashi Takuji , Sakai Takaaki , Kanega Ryoichi , Funaki Takashi , Sato Yukari , Ohira Akihiro 
Published: February 2024

Redox flow battery (RFB) is a promising candidate of large-scale stationary energy storage which is necessary to utilize renewable energy. For RFBs, the capability to easily increase the capacity by enlarging the electrolyte tank, high charge-discharge cycle performance, and wide flexibility to high- and low-frequency fluctuations are highly advantageous.
Nowadays vanadium RFBs are used for practical use, but the material cost of vanadium is problematic to further spread them. An alternative candidate for commercial use is titanium-manganese (Ti-Mn) RFBs [1] whose material cost should be lower. On the other hand, the stability of the electrolyte for positive electrode (catholyte) need to be improved, because precipitates are created by a charge disproportionation reaction of Mn ions in the charged catholyte [2]. The formation of precipitates decreases the energy density and degrades the cyclability. To improve the characteristics, the chemical state and redox reaction of the electrolytes of Ti-Mn RFBs should be clarified by precise analyses.
We performed synchrotron radiation X-ray absorption spectroscopy (XAS) for the electrolytes of a Ti-Mn RFB to directly observe the redox reaction [3]. In this study, the same Ti-Mn RFB electrolyte was used for both positive and negative electrodes. The Ti K-edge XAS of the electrolyte for negative electrode (anolyte) revealed gradual reduction reaction of Ti from Ti4+ on the charge process. The Ti L
2,3-edge XAS spectrum for the anolyte at state of charge (SOC) of 80% was mostly attributed to Ti3+ state. The results for Ti are consistent with electrochemical views in previous reports [2]. The Mn K-edge XAS of the catholyte gradually shifted to higher energy-side up to SOC of 50%, indicating a slight oxidation reaction of Mn from Mn2+. However, the Mn L
2,3-edge XAS spectrum for the catholyte solution at SOC of 80% was of Mn2+ state that was not changed from the initial state. Instead, scanning transmission X-ray microscopy (STXM; XAS mapping with a high spatial resolution) at the Mn L
3-edge unveiled that the precipitates mostly consist of Mn4+. Thus, the charge disproportionation reaction of 2Mn3+ -> Mn2+ (solution) + Mn4+ (precipitates) in the charged catholyte was confirmed. In the presentation, the electronic-structure change of the Ti and Mn ions in both catholyte and anolyte will be discussed in detail.

References

[1] T. Shigematsu, Curr. Opin. Electrochem.
18 (2019) 55-60.
[2] Y. R. Dong et al., SEI Technical Review
84 (2017) 35-40.
[3] D. Asakura et al., Chem. Asian J.
18 (2023) e202201047.
High-Throughput Screening of Molecules for Flow Batteries
Authors: Peljo Pekka , Gonzalez Gabriel , Martínez González Eduardo , Li Qiujun , Hannonen Jenna , Mattinen Ulriika , Hamza Andrea , Németh Flora , Madarasz Adam , Papai Imre , Nechaev Anton , Pihko Petri M 
Published: February 2024

Development of next generation stationary energy storage technologies is of crucial importance for increasing the share of the intermitted renewable electricity generation in the world. Traditional trial and error based approach for discovery of novel materials is very slow, so we have been thinking of how to accelerate the process. Some crucial parameters such as redox potentials can be readily evaluated with computational tools, such as those developed in our CompBat project [1], [2], but other parameters such as stability are more difficult to be evaluated. In this work we will demonstrate our web-based application for evaluating redox potentials of molecules from the SMILES structure, illustrating very impressive or problematic performance depending on the training data used for the model.
For the question of stability, we believe that sufficient quantity of experimental data is required for training of specific machine learning models for stability prediction. For this purpose, we will illustrate our experimental approach for high-throughput electrochemistry, to evaluate the stability of molecules in the time-scale of voltammetry. Moreover, we will discuss the order of magnitude of the kinetics of the decomposition reactions that can be evaluated by voltammetry, and illustrate that voltammetry is a good tool for roughly separating more stable species from the less stable, but other techniques are required for evaluating stability in the time scale of battery operation.
References

https://compbat.eu/

A. Hamza, F.B. Németh, Á. Madarász, A. Nechaev, P. Pihko, P. Peljo, I. Pápai, N-alkylated pyridoxal derivatives as negative electrolyte materials for aqueous organic flow batteries: Computational screening, 10.26434/chemrxiv-2023-bzc6w
Electrochemical Evaluation of Manganese Electrolytes for Redox Flow Batteries
Authors: Villar Erlantz , Khataee Amirreza , Lindstrom Rakel 
Published: February 2024

Redox flow batteries (RFBs) are promising candidates for long-duration energy storage mainly due to the lower cost of improving the energy density compared to lithium-ion batteries. However, the full sustainability of RFBs has not been achieved yet, and there is a lot of room for further improvement. One of the main parameters showing a strong influence on the sustainability of RFBs is redox active materials. In this work, manganese was selected for electrochemical evaluation as it fulfills the sustainability requirements. Manganese is a non-toxic, low-cost and abundant material with sufficient aqueous solubility[1]. Moreover, the standard potential of manganese (1.51 V) is higher than that of vanadium (1.26 V).
For electrochemical parameters, we have, through cyclic voltammetry (CVs) and polarization curves, estimated the diffusion coefficient (D0
) and heterogeneous standard electron transfer rate (k
0) of manganese in an acidic electrolyte in the presence of titanium as an additive. In order to investigate the performance of an RFB system using a manganese electrolyte, a hybrid system was designed that uses hydrogen gas on the negative side and an acidic manganese electrolyte the positive side. We have studied the resistance behavior of the hybrid RFB through electrochemical impedance spectroscopy at different states of charge. From EIS data, cell ohmic resistance, and a general idea of the different processes taking place at different state of charge were obtained. Moreover, we studied the performance of the hybrid RFB during 70 cycles, obtaining an average coulombic efficiency of 98.1%, voltage efficiency of 77.8% and capacity retention of 97.7%.

Carney, J.R., B.R. Dillon, and S.P. Thomas, Recent Advances of Manganese Catalysis for Organic Synthesis. European Journal of Organic Chemistry, 2016. 2016(23): p. 3912-3929.
Fabrication and Performance of Symmetric Flow Battery Systems Incorporating Novel Pyridinium Anolytes
Authors: Samaroo Sharmila , Hengesbach Charley , Opolka Taylor D. , Kruper William R. , Hickey David , Guarr Thomas F. 
Published: February 2024

The push to bring more renewable energy sources onto the grid has spawned a flurry of work to develop viable options for long duration energy storage. Redox flow batteries (RFBs) represent one of the most attractive possibilities, and research toward employing redox-active organic materials to improve or replace the incumbent commercially available vanadium-based RFB technology is burgeoning. In particular, numerous pyridinium-based salts have been extensively studied as anolytes in both aqueous and nonaqueous RFBs. We have recently reported a series of readily synthetically accessible 2,6-dimethyl-4-arylpyridinium compounds that display quite negative reduction potentials (ca. -1.55 to -1.8 V vs Fc/Fc+), along with high solubility and excellent electrochemical kinetics. Some of these materials are also extremely persistent in the reduced state, suggesting that they may be good candidates for RFB applications.
In this presentation, we will describe the preparation and properties of new pyridinium compounds from the corresponding pyrylium precursors, as well as the fabrication of symmetric RFB systems in which these materials are covalently linked to phenothiazine or ferrocene catholyte moieties. Synthesis, solubility, and electrochemical performance (including preliminary RFB cycling data) of these materials will also be discussed.
Electrode Imbibition and Surfactant Interactions with Vanadium Flow Battery Electrolytes
Authors: Imel Adam , Barth Brian , Zawodzinski Thomas A. 
Published: February 2024

Redox flow batteries (RFB) are a critical technology for stationary grid-scale energy storage, with potential usage with intermittent power sources, such as wind and solar. RFBs are attractive for long-duration energy storage because the anolyte and catholyte are stored separately external to the electrochemical reactor. Separating the electrolytes and the electrochemical cell decouples energy and power densities, unlike batteries that store charge in the solid-state, such as Li-ion, Pb-acid, or Ni-Cd. A standard RFB chemistry is the all-vanadium redox flow battery (VRFB), which utilizes the four oxidation states of vanadium, with V2+, V3+, V4+, and V5+. Recently our group found that adding small amounts of sodium dodecyl sulfate (SDS) to a VFRB increased the kinetics of the V2+ to V3+oxidation.
Furthermore, surfactants play essential roles in battery manufacturing and operation. Surfactants can change metal oxide crystal structure, inhibit dendrite growth, limit corrosion, and prevent nanoparticle agglomeration. Surfactants are never wholly removed during manufacturing and can be present during battery operation. Therefore, it is crucial to understand how surfactants impact battery performance and their effect on the materials.
This talk describes SDS's equilibrium surface properties and adsorption characteristics at the liquid−air and liquid-solid interfaces, thus providing insights into the interactions of SDS with a VFRB electrolyte. Experiments focusing on the effects of sulfuric acid and vanadium ions on SDS's equilibrium surface tension and critical micelle concentration (CMC) were completed. The Szyszkowski equation is used to calculate SDS's adsorption parameters, such as interfacial surface excess, Γsz [mol/m2], the surface excess at the saturated interface, Γ∞ [mol/m2], the minimum molecular area in the adsorption layer at the saturated interface, Amin [nm2], and the Gibbs free energy of adsorption, ΔGads [kJ/mol]. Furthermore, an examination of the spontaneous imbibition of the VFRB electrolyte with SDS into a porous carbon electrode is presented. The microstructure of porous systems, interfacial tension, and fluid−solid interactions controls the capillary-driven flow and is vital in multiphase flow in porous media. Therefore, understanding SDS's effects on the VFRB electrolyte in an electrode is critical to understanding the electrochemical reactions and molecular interactions occurring.
This work was supported as part of the Breakthrough Electrolytes for Energy Storage and Systems (BEES2), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409.
(Invited) Relationship of Pseudo-Capacitive Current in Sulphuric Acid and Vanadium Flow Battery Reaction Kinetics at Carbon Electrodes
Authors: Al Hajji Safi Maria , Buckley D. Noel , Bourke Andrea , Lynch Robert P. 
Published: February 2024

Flow battery technologies are promising solutions to the need for electricity storage driven by the increasing demand for energy supply at the same time as the electricity grid becomes more and more dependent on renewable sources such as solar, wind and ocean energy. Vanadium flow batteries (VFBs) are perhaps the most promising of these technologies and a growing number of commercial systems are in operation worldwide.
The energy efficiency of vanadium flow batteries (VFBs) largely depends upon the performance of the electrodes. Poor electrode kinetics cause large overpotentials, which reduce the voltage efficiency. They can also lead to side reactions, such as hydrogen evolution at the negative electrode and oxidation of the positive electrode, which reduce the coulombic efficiency and the overall performance and durability.
There is considerable variation in the data regarding the kinetics of vanadium redox reactions at carbon electrodes. We have previously reported that cathodic treatment enhances the kinetics of the positive (VIV-VV) electrode in VFBs but inhibits the kinetics of the negative (VII-VIII) electrode, while anodic treatment inhibits the kinetics of the positive electrode but enhances the kinetics of the negative electrode1-3. We also showed that the activity of carbon-based material is strongly dependent on the surface history, in particular the most positive and the most negative potential used to treat an electrode4. In this presentation we will further investigate the effect of electrochemical treatment of the carbon surface and show the relationship between the observed pseudo-capacitive behavior and the kinetics of the different vanadium redox couples.

References

Bourke, M. A. Miller, R. P. Lynch, X. Gao, J. Landon, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc.
163, A5097 (2016).

A. Bourke, M. A. Miller, R. P. Lynch, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc., 162, A1547 (2015).

M. A. Miller, A. Bourke, N. Quill, J. S. Wainright, R. P. Lynch, D. N. Buckley and R. F. Savinell, J. Electrochem.
Soc., 163, A2095 (2016).

M. Al Hajji Safi, A. Bourke, D. N. Buckley, R. P. Lynch, ECS Trans., 109, 67-84 (2022).
Expanding the Scanning Electrochemical Microscopy Toolset for Evaluating Electron Transfer Kinetics of Concentrated and Specialized Redox Electrolytes on Carbon Surfaces
Authors: Gaddam Raghuram , Qian Peisen , Rodriguez Lopez Joaquin 
Published: February 2024

Performing quantitative measurements of heterogeneous electron transfer reactions at electrodes (e.g., determining k0 and a) under conditions of high redox active molecule concentration in solution, such as those encountered in electrolytes for redox flow batteries (RFBs), presents significant technical challenges. For example, attempting to use transient voltammetry methodology quickly leads to limitations imposed by iR drop, as currents can be large and resistance, especially in non-aqueous systems, can be high. Additionally, using steady-state techniques based on convective principles, such as the rotating disk electrode (RDE), involve the use of relatively large equipment, with moving parts, and usually with requirements of tens to hundreds of mL of solution, which may be limiting for exploring new compounds at high concentration.
To address these issues, here we introduce the use of scanning electrochemical microscopy (SECM) for the determining the rates of electron transfer of redox active species at high concentration in non-aqueous [1] and other unconventional systems, such as deep eutectic solvents. SECM enables the resolution of higher rates of electron transfer compared to transient voltammetry and RDE, and it also enables experiments with spatial resolution, enabling the exploration of reactivity on various sites of a heterogeneous electrode. In this presentation, we will describe theoretical and practical aspects of these measurements, and we will demonstrate their utility using two model systems. The first one consists on the observation of inherent rate asymmetries observed for ferrocene derivatives, ubiquitous redox probes, at the graphite/carbonate solvent interface. These asymmetries are not present on aqueous systems or metallic electrodes, demonstrating the ability of the SECM technique to capture unique behaviors. In the second case, we will discuss how SECM measurements can be used on deep eutectic solvents such as ethaline to address how interactions between redox actives and the electrode or the solvent systems modulate the rate of electron transfer. By systematically modifying the strength of interactions by means of molecule choice, solvent composition, and electrode type and structure, we can gain insight into the processes that determine reactivity at redox flow battery electrodes. This insight is critical for exploring the interfacial aspects such as adsorption, passivation, and double-layer effects on kinetics of electron transfer.
[1] Gaddam, R.; Sarbapalli, D.; Howard, J.; Curtiss, L.A.; Assary, R.S.; Rodríguez-López, J. An SECM-Based Spot Analysis for Redoxmer-Electrode Kinetics: Identifying Redox Asymmetries on Model Graphitic Carbon Interfaces Chem: Asian J., 2023, 18, 2, e202201120.

Figure 1
Nanoisland Formation on the Low Index Planes of Pt By Repeated Electro-Oxidation and-Reduction
Authors: Fuchs Timo , Schroefel Fabian , Fehrs Jan Ole , Merkel Nick , Kempf Simon , Bunge Jonas , Qiu Canrong , Harrington David A. , Drnec Jakub , Magnussen Olaf M. 
Published: February 2024

Pt-based electro-catalysts are the most common cathode material in proton exchange membrane fuel cells given their high oxygen reduction reaction activity and stability. However, practical applications are limited by catalyst performance loss and degeneration. A main cause for this is nanoscale Pt surface restructuring, which occurs upon formation and reduction of a Pt surface oxide. During oxidation, a fraction of the Pt surface atoms are extracted in a process known as “place-exchange” from the electrode and are bound at specific sites in an oxide about 1 – 4 Å above the surface [1]. Upon subsequent oxide reduction, these atoms as well as the vacancies from which they originate can agglomerate, leading to the nucleation of adatom and vacancy islands. If this process is repeated, nanoislands with a well-defined lateral size of about 20 – 60 Å are grown [2-6]. Detailed studies of this growth process have been performed on the Pt(111) electrode [2-6], revealing two distinct growth regions which are characterized by different vertical scaling exponents [3].
For the development of catalysts with superior long-term stability, a more detailed knowledge of the restructuring of the other low index planes of Pt is required. In our recent study of the Pt oxides on Pt(111) and Pt(100) we already showed a strong dependence of the structural stability of the surface on differences in the atomic-scale oxide structure formed on those two surface orientations [1]. However, the influence of surface structure on the nanoisland growth after repeated oxidation and reduction is largely unclear.
We present a comparative operando grazing incidence small angle X-ray scattering (GISAXS) study of the nanoisland formation on Pt(111), Pt(100) and Pt(110) in acidic electrolyte. The GISAXS measurements of the nanoisland growth were performed at a high photon energy of >70 keV, which lowered background scattering from the electrolyte, enabling us to resolve the islands after the very first ox./red. cycle. Differences in island shape and growth behaviour on the low index planes will be discussed.
We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft via project no. 418603497, MA 1618/23-1 and the BMBF via 05K19FK3.
References

Fuchs et al., Nat. Catal. 3, 754–761 (2020)

Sugawara and K. Itaya, J. Chem. Soc., Faraday Trans. 185, 1351-1356 (1989)

Jacobse et al., Nat. Mater. 17 (3), 277-282 (2018)

J. Rost, et al., Nat. Commun. 10, 5233 (2019)

Ruge et al., J. Am. Chem. Soc. 139, 4532 (2017)

Jacobse, et al. ACS Cent. Sci. 5 (12), 1920–1928 (2019)
Solar Energy Is Effectively Converted to Electricity and Hydrogen Using Cyanobacteria
Authors: Lee Youngrok , Lee Jihhwan , Kim Sunghyun 
Published: February 2024

We present solar energy conversion for electricity generation and hydrogen production from water using Anabaena variabilis (A. variabilis), an oxygenic photosynthetic cyanobacterium. Electrons from water oxidation by the light reactions that take place in thylakoid membranes (TMs) undergo a series of electron transfer pathway called Z-schme. We devised a method in which electrons are directed to the external electrode. In order to extract electrons from TMs, we found that double mediators are very effective in transferring electrons to the electrode from TMs. Dimethylbenzoquinone, the first mediator, can take electrons from the Z-scheme and delivers them to ferricyanide, the second mediator. Thus transferred electrons move to the cathode where oxygen reduction reaction takes place. Figure shows how biosolar cell (BSC) is operating under illumination.
Electricity generation was achieved by simply attaching an external load between the anode and the cathode. When A. variabilis was dispersed in solution, the maximum photocurrent up to 2.14 mA cm-2 upon one sun light intensity. A complete cell produced Pmaxof 160 mW cm-2 at 750 mA cm-2 with a quantum efficiency of 4.8% over a whole spectral range and turnover frequency of 17 per PSII for water molecule oxidation. The same concept was also applied to the hydrogen production. When operated in a double-chamber reactor under anaerobic condition, pure hydrogen gas was produced from water with high energy efficiencies and high production rates upon voltage bias. The maximum H2 production rate of 122 mmol H2(mg Chla)-1h-1 at anode potential of 0.4 V vs. Ag/AgCl was achieved. Energy efficiency exceeded 100% at lower anode potentials. We expect that this study opens a new way of utilizing cyanobacteria for appreciable electricity and hydrogen production. The same concept could be extended to other oxygenic cyanobacteria.

Figure 1
DFT Studies on Cun/TiO2 (n=1-7) System for Water Splitting
Authors: Tokarz-Sobieraj Renata , Kaipanchery Vidya , Drzewiecka-Matuszek Agnieszka , Rutkowska-Zbik Dorota 
Published: February 2024

Copper deposited on titania is active in numerous catalytic reactions, incl. water splitting [1]. The activity of the system depends on the size of the copper phase, whether it is present as single atoms, sub-nanometer clusters, or nanoparticles.
The aim of the current contribution is to elucidate the relationship between the size of the copper active phase and its electronic and geometric properties by performing Density Functional Theory (DFT) calculations with PBE functional and the def2-TZVP basis set.
Theoretical model of the system comprised of a cluster model of anatase phase of titania – (TiO2)34 - with clusters of copper of varying sizes on top of it. The ground-state geometric and electronic structures were elucidated. Next, their redox and photochemical properties were determined: frontier (HOMO, LUMO) orbitals were defined, energy gaps, total and partial density of states were plotted and analysed. The interactions between components of the systems, in particular the influence of the support on the copper electronic structure, were investigated. Next, the reactivity of the metal phase towards typical intermediates observed during water splitting (H2O, OH, O, and H) was studied.
The performed calculations demonstrated that the presence of metal determines the energetics and character of the frontier orbitals of the catalyst. The size of copper active phase influences the bond lengths and bond orders with studied reagents.
Acknowledgements: This work was supported by the National Science Centre, Poland within Solar-Driven Chemistry project no 2019/01/Y/ST4/00024. This publication is based upon work from COST Action CA 18234 “Computational materials sciences for efficient water splitting with nanocrystals from abundant elements”, supported by COST (European Cooperation in Science and Technology). We gratefully acknowledge Polish high-performance computing infrastructure PLGrid (HPC Centers: ACK Cyfronet AGH) for providing computer facilities and support within computational grant no. PLG/2020/013927.
Literature:
[1] Cheng Cheng, Wei-Hai Fang, Run Long, and Oleg V. Prezhdo, JACS Au 2021, 1, 5, 550–559