bluuebunny/crossref_metadata_2025 huggingface dataset:
Changing Mechanisms for CO2 Reduction to Formate Via Protonation of the Catalyst
Authors: Lee Kevin , Berben Louise A. , Aceves Marcos
Published: August 2024

Electrochemical reduction reaction of CO2 (CO2RR) is a promising method to transform CO2 to useful products for consumption such as formic acid, carbon monoxide, or methane. Simply increasing the driving force of a catalytic process to speed up the rate of CO2 reduction is unviable because of the competing Hydrogen Evolution Reaction (HER) pathway and of increased energy cost. Controlling the reactivity of active intermediates is of substantial importance for such processes. [Fe4N(CO)12]− is a formate selective electrocatalyst previously studied by our group and was modified through protonation and replacement of several CO ligands with triethylphosphines (PEt3) to synthesize [HFe4N(PEt3)4(CO)8] . This PEt3 substituted, pre-protonated analog of [Fe4N(CO)12]− exhibits altered rates compared to a non-protonated analog which we attribute to a switch in mechanism. We further explore explanations for different rates despite similar “active intermediates” and similar driving force using Cyclic Voltammetry (CV).
(Invited) Multiplexed CRISPR-Based ECL Assay for Alzheimer’s Biomarkers
Authors: Hiniduma Keshani , De Silva P.I. Thilini , Shawky Sherif , Canete Rachelle , Bhalerao Ketki S. , Rouge Jessica L. , Rusling James F.
Published: August 2024

Currently, more than 6 million Americans live with Alzheimer’s disease (AD), and it is projected to be 13 million by 2050. AD has no permanent cure yet, and early detection is important to slow down the progress of the disease. Diagnosis is complicated by AD’s similarity to other geriatric diseases. Beta-amyloid peptide (Aβ42), tau proteins and neurofilament light (NFL) measured in the cerebrospinal fluid (CSF) is a reasonably effective method for diagnostics, but very painful for the patients. MicroRNA’s (miRNAs) expressed in the brain are promising biomarkers and our goal of this study is to develop a sensitive and selective point-of-care (POC) test to detect AD specific miRNA (miRNA 30e, 34c and 200c) based on the CRISPR-Cas system. The Cas 13a protein has the regular sequence specific RNase activity followed by a collateral RNase activity. We used this feature of Cas 13a to generate an electrochemiluminescence (ECL) signal by binding specific miRNA biomarkers, and then collaterally cleaving poly-ribose guanine (poly-rG). This cleaved strands of poly-rG and rG itself are coreactants for ECL, and react with ECL polymer Ruthenium Polyvinyl Pyridine (RuPVP) to generate ECL. RuPVP is deposited into pyrolytic graphite (PG) micro wells. Using a 3D-printed microfluidic device equipped with the Pt reference and Ag/AgCl counter electrodes, patient serum mixed with poly-rG is introduced to the RuPVP coated electrode at 1.3 V to provide ECL light measured by a CCD camera. The assay was multiplexed to detect 3 AD specific miRNAs, and obtain a separate calibration for each miRNA biomarker with linear ranges from 70 pg/ mL to 7 µg/mL, from 7.4 pg/ mL to 74 µg/ mL and from 7.4 fg/ mL to 74 µg/ mL for 30e, 34c and 200c respectively. Preliminary LODs were 42 pg/ mL, 0.074 fg/ mL and 0.15 fg/ mL for miRNA 30e, 34c and 200c respectively. Results confirm the sensitivity of the assay. Further, spike recovery, cross reactivity studies and patient sample assays will be reported.
Triggering Tau Fibrillization by Electroreduction: A New Tool for Studying Amyloid Diseases
Authors: Masquelier Eloise , Fojut Sabrina , He Xaotian , Tochikura Seren , Sepunaru Lior , Gordon Michael J. , Morse Daniel E
Published: August 2024

The pathological aggregation of the microtubule-associated protein tau is a hallmark of various neurodegenerative disorders, including Alzheimer’s disease (AD), Pick’s disease and frontotemporal dementia. Tau protein’s reversible assembly and binding to microtubules in brain neurons are regulated by charge-neutralizing phosphorylation. Hyperphosphorylation, on the other hand, leads to irreversible formation of cytotoxic filaments. Under physiological conditions, tau remains remarkably stable, exhibiting intrinsically disordered behavior and reversible assembly. Irreversible aggregation requires specific mutations, preformed seeds or nucleating polyanionic cofactors. However, heparin-induced fibrils differ structurally from brain-derived filaments, and the presence of such cofactors can impede therapeutic agent development. We have developed a quick and easy method to generate cofactor-free filaments using heterogeneous electroreduction as a surrogate for charge-neutralization by hyperphosphorylation. We combine electrochemistry with in situ UV absorbance, circular dichroism and dynamic light scattering spectroscopies to dynamically follow tau’s conformational changes and assembly. Electroreduction of positively charged residues of the protein leads to rapid formation of b-rich structures, even at times as short as 15 minutes. The extent of assembly can be controlled by fine-tuning electroreductive potentials and electrolyte conditions. Relevance of this new method was confirmed by examining the impact of an early-onset AD-causing tau mutant and known inhibitors on aggregation kinetics. Our results demonstrate comparable effects to heparin-induced fibrils, as assessed by thioflavin-T fluorescence, dynamic light scattering, circular dichroism and electron microscopy. Low-voltage electroreduction provides a platform to study the effects of tau mutations and effectors, as well as to develop rapid assays to test how additional effectors may inhibit, disassemble or direct the trajectory of tau assembly. The versatility of our approach also suggests its potential applicability to a broader spectrum of neurodegenerative amyloid diseases.
In-Situ Investigation of Surface Modifiers Dithiocarbamates on Au Electrodes for Electrochemical CO2 Reduction
Authors: Lu Jiayao , Nichols Eva Megan
Published: August 2024

Molecular functionalization of metal electrodes via self-assembled monolayers (SAMs) can introduce synthetically tunable properties to metal surfaces and has exhibited great potential in electrocatalysis. Alkanethiols are commonly used organic ligands because of their strong affinity to Au but they are prone to desorption at negative potentials. Alternatively, dithiocarbamates (DTC) show superior electrochemical stability. In this study, a series of DTCs, differing in hydrophobicity, size, and steric bulk, were synthesized to prepare SAM-functionalized Au electrodes. The properties of the resulting surfaces (e.g. wettability, surface coverage, and reductive stability) were investigated by analytical and electrochemical techniques. Particularly, in-situ approaches such as surface-enhanced infrared absorption spectroscopy (SEIRAS) are employed to characterize the molecularly modified interface. The novel catalyst platforms were explored for electrochemical CO2 reduction.
A Comprehensive Online Analytical System Coupled with Standardized Data Analysis for the Electrochemical Reduction of CO2
Authors: Senocrate Alessandro , Kraus Peter , Bernasconi Francesco , Battaglia Corsin
Published: August 2024

The electrochemical reduction of CO2 (CO2RR) is a promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and thus to achieve a circular carbon economy.
1 Depending on catalyst type and reaction conditions, different gaseous and liquid products can be obtained from the CO2RR, and their production rates vary with reaction time. It becomes thus imperative, for any catalytic performance analysis, to be able to assess the product distribution online during CO2RR.
2,3 However, while gaseous products are readily analyzed online by gas chromatography, liquid products are typically only assessed at the end of the reaction due to the lack of suitable automated liquid sampling and analysis methods. In addition, reaction parameters such as CO2 mass flow rates, temperatures and pressures are seldom recorded, causing the loss of significant information on catalysts, electrodes, and electrolyzers behavior.

To overcome these issues, we assemble a comprehensive analytical system coupling online gas and liquid product analysis by gas and liquid chromatography leveraging a special automated liquid sampling valve with electrochemical protocols that assess CO2RR performance, electrolyzer cell resistance and electrode surface area. In addition, we record CO2 mass flow rates, electrolyzer temperatures, as well as gas and liquid flow pressures.
4 To rapidly and reproducibly handle the large and heterogeneous data volume obtained we implement a standardized data pipeline based on our own open-source software,5 which automatically parses the numerous different raw data files, composes a data set following FAIR practices,6 and post-processes and plots the data in a standardized way. We validate the analytical system by carrying out CO2RR at 200 mA/cm2 on Cu gas diffusion electrodes, following the changes in selectivity with reaction time for > 10 gaseous and liquid products, and recording mass flow rates, electrolyzer temperatures and pressures. The modular nature of our analytical system, combined with the standardized data pipeline, allows us to freely increase the number and type of sensors used with minimal impact on the data analysis time, as well as to multiplex our analysis to 8 parallel electrolyzer cells, paving the way for a much deeper and faster understanding of the function of CO2RR catalysts, electrodes, and electrolyzers.

References

[1] Senocrate, Battaglia, J. Energy Storage
2021, 36, 102373.

[2] Wang, de Araújo, Ju, Bagger, Schmies, Kühl, Rossmeisl, Strasser, Nat.
Nanotechnol.
2019, 14, 1063.

[3] Löffler, Khanipour, Kulyk, Mayrhofer, Katsounaros ACS Catal.
202
0, 10, 6735.

[4] Senocrate, Kraus, Bernasconi, Battaglia, in preparation,
2023.

[5] https://dgbowl.github.io

[5] Kraus, Vetsch, Battaglia, Journal of Open Source Software
2022, 7, 4166.
Polybenzimidazole Membranes for Waste Stream Remediation to High Value Products
Authors: Likit-anurak Kris , Karki Ishwor , Howard Ben , Shimpalee Sirivatch , Benicewicz Brian , Meekins Benjamin
Published: August 2024

Electrochemical remediation of industrial waste products represents an economically attractive method to continuously convert waste streams to high value products. Electrochemical remediation has been more limited for processes that are very dry, very acidic, or a combination of both, because the most widely used polymer membranes (for example, Nafion™) need external humidification to maintain conductivity. We show that para-polybenzimidazole (PBI) membranes can be used as an effective polymer membrane separator in these types of harsh environments, improving the performance of the current state-of-the-art aqueous HCl electrolyzer, enabling the first completely anhydrous gas-phase HCl electrolyzer, and pushing the electrolysis of SO2 in the Hybrid Sulfur (HyS) cycle to the point of economic viability. The discussion will also cover how PBI membrane preparation affects electrochemical performance and the development of a Computational Fluid Dynamics (CFD) model that both provides insight into the transport phenomena of the anhydrous electrolyzer and allows us to examine operating parameters that are dangerous experimentally.
Effect of pH on the Selectivity of γ-MnO2 Electrocatalysts Towards Oxygen Evolution Reaction in the Presence of Chloride Ions in Alkaline Environment
Authors: Baturina Olga A , Finn Matthew , Weathers Brandice
Published: August 2024

This paper reports on progress in development of electrocatalysts intended for use in seawater, which optimize the balance of competing reactions between chlorine evolution and oxygen evolution. The oxygen evolution reaction (OER) from H2O is thermodynamically more favorable due to a lower equilibrium potential [1]. However, chlorine evolution successfully competes with the OER due to faster kinetics. One of a few catalysts that demonstrates high selectivity towards the OER in the presence of chloride ions in the alkaline environment (i.e. pH 12) is γ-MnO2 [2].

In this presentation, we (1) compare activities and selectivities towards the OER of electrodeposited and chemically synthesized γ-MnO2 and (2) determine how pH affects selectivity in the pH range from 11 to 13.

g-MnO2 powder was synthesized using hydrothermal method. The synthesis resulted in fabrication of material with a flower-like morphology, characterized by a crystallite size of 5-15 nm and BET surface area of 75 m2/g. In parallel, MnO2 films were prepared by electrodeposition on a Pt RDE substrate, following the procedure outlined by Tsagareli et al. [3]. The electrocatalytic activity of both γ-MnO2 powder and electrodeposited MnO2 was investigated by the thin-film RDE method. The thin films of γ-MnO2 powder were obtained by drop-casting MnO2/VC ink [1] on glassy carbon substrates.

We found that the shape of polarization curves on MnO2/VC films is strongly dependent on the Nafionä loading. At low Nafion loadings, we observe diffusion-limited currents, which we attribute to OH- diffusion through the Nafion. At higher Nafion loadings, neither diffusion-limited currents, nor the currents’ dependence on the rotation rate are observed. Our data indicate that at low Nafion loadings, MnO2/VC films selectively produce O2 in 0.5M NaCl at pH 12 and 13 and current densities up to 15 mA/cm2. Because of the potential effect of Nafion on the permeability of Cl-
ions to the catalyst’s active sites, a set of parallel experiments is being carried out on the electrolytically deposited MnO2 films. The results of the latter experiments will be compared to those obtained on MnO2/VC films in the presentation.

References

[1] F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, P. Strasser, Chemsuschem, 9 (2016) 962.

[2] K. Fujimura, T. Matsui, K. Izumiya, N. Kumagai, H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto, Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 267 (1999) 254.

[3] G. Tsagareli, S. Makhatadze, M. Soselia, N. Maisuradze, Journal of the Indian Chemical Society, 99 (2022).
Advancing Catalyst Performance in Electrochemical Water Splitting
Authors: Zlatar Matej , Cherevko Serhiy
Published: August 2024

The transition to renewable energy, vital for a sustainable future, frequently encounters challenges such as low energy density and intermittency. A promising solution lies in converting renewable energy into chemical bonds, notably hydrogen, through electrochemical water splitting. This process, however, is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) at the anode. Consequently, this necessitates the use of rare and expensive iridium-based catalysts. Given that iridium is the only metal resilient enough to withstand the harsh anodic conditions of OER, reliance on it poses significant economic challenges, making water electrolysis less competitive compared to fossil fuel-based technologies.

In response to these challenges, our research has two main objectives. First, we aim to understand the often observed trade-off between iridium OER activity and stability. (1) Second, we intent to enhance our understanding of catalyst-support interactions by explore the use of conductive and potentially durable materials as supports for iridium to improve efficiency, a critical yet largely unexplored area.

To achieve these goals, we employ advanced techniques, including inductively coupled plasma mass spectrometry coupled with scanning flow cell. This method enables us to perform detailed potential and time-resolved stability analyses.

Specifically, we conduct an in-depth investigation of the impact of pH across a range from acidic to alkaline environments. Furthermore, we explore a variety of backing electrodes, investigate accelerated stress tests (AST) parameters, (2) and assessing how catalyst loading and Nafion content affect the performance and stability of iridium catalysts.

Our findings provide a deeper understanding of iridium’s stability during OER and highlight the importance of catalyst-support interactions. (3, 4) By addressing the key challenges associated with iridium-based catalysts, this knowledge is crucial for the development of more cost-effective catalysts with minimized use and hence sustainable water electrolysis technologies, marking a step closer to realizing more efficient and economically viable methods for harnessing and storing renewable energy.

References:

S. Cherevko, A. R. Zeradjanin, A. A. Topalov, N. Kulyk, I. Katsounaros and K. J. J. Mayrhofer, ChemCatChem, 6, 2219 (2014).

M. Zlatar, D. Escalera-López, M. G. Rodríguez, T. Hrbek, C. Götz, R. Mary Joy, A. Savan, H. P. Tran, H. N. Nong, P. Pobedinskas, V. Briega-Martos, A. Hutzler, T. Böhm, K. Haenen, A. Ludwig, I. Khalakhan, P. Strasser and S. Cherevko, ACS Catalysis, 13, 15375 (2023).

M. Zlatar, D. Nater, D. Escalera-López, R. M. Joy, P. Pobedinskas, K. Haenen, C. Copéret and S. Cherevko, Electrochimica Acta, 444, 141982 (2023).

R. A. Krivina, M. Zlatar, T. N. Stovall, G. A. Lindquist, D. Escalera-López, A. K. Cook, J. E. Hutchison, S. Cherevko and S. W. Boettcher, ACS Catalysis, 13, 902 (2023).
Proton Transfer Kinetics at a Defect-Free Liquid-Liquid Interface
Authors: D'Antona Nicholas R , Barnard Nadia F. , Kempler Paul A. , Boettcher Shannon W.
Published: August 2024

Proton transfer at electrochemical interfaces is fundamentally important for many areas of science and technology, yet kinetic measurements of this elementary step are often convoluted by inhomogeneous electrode surface structures. We show that facilitated proton transfer at the interface between two immiscible electrolyte solutions (ITIES) can serve as a model system to study proton transfer kinetics in the absence of defects found at solid|electrolyte interfaces. Diffusion-controlled micropipette voltammetry revealed that 2,6-diphenylpyridine (DPP) facilitated direct proton transfer across the liquid|liquid interface and voltammetry at nanopipette-supported interfaces yielded activation-controlled ion transfer currents. The exchange current density for proton transfer at the ITIES is comparable to exchange current densities recently reported for H-UPD on Pt (111) and provides the first direct means of comparing ion transfer kinetics between solid|liquid and liquid|liquid interfaces, supporting the development of a general theory of ion transfer kinetics.
Porous Bismuth Vanadate Photoelectrodes for Solar Water Oxidation Reaction
Authors: Pattadai Jayaraman Jayanthan , Goldman Benjamin , Harbauer Karsten , Johnson Hannah , Sivula Kevin , van de Krol Roel
Published: August 2024

Bismuth vanadate (BiVO4), a material known for its high visible light activity and good stability, is a promising candidate as a photoanode for overall water splitting [1]. Its performance is limited by its relatively short charge carrier diffusion length, which has recently been estimated to be ~15 nm [2]. For these kinds of photo-absorbers, commercial flat transparent conducting oxide (TCO) substrates are unsuitable since the thickness needed to absorb a sufficient amount of light far exceeds the carrier diffusion length. With this in mind, deposition of very thin semiconductor film onto the internal structure of (micro)porous, conducting substrates can ensure sufficient light absorption [3], whilst ensuring the individual film thickness is uniformly lower than the carrier diffusion length. Nanostructured TCO substrates can be fabricated using a convenient template-free technique called glancing angle deposition (GLAD). The glancing angle deposition method can be used to synthesize different variations of highly oriented submicron-sized pillars, ranging from vertical and tilted columns to zig-zag and helical structures with the help of shadowing effects and substrate rotation [4]. The optical and electrical properties of nanostructured TCO’s were found to depend on the type of material and the substrate temperature during deposition. We find that pillars made from tin-doped indium oxide show good conductivity (79 Ohm/sq) and are promising for the fabrication of nanostructured substrates for bismuth vanadate. A recently developed alternative approach is the use of transparent, porous, conducting substrates (TPCS) made from quartz felt, in which the quartz fibers are coated with F-doped SnO2 [5]. We found that a BiVO4 film thickness of 50 nm within these porous substrates is enough to absorb the same amount of light as a compact 400 nm bismuth vanadate film. We will discuss the deposition of BiVO4 into the TPCS substrates and the photoelectrochemical performance of these porous photoanodes.

[1] K. Sivula and R. van de Krol, Nat. Rev. Mater. 1, 15010 (2016)

[2] M. Schleuning, M. Kölbach, F. F. Abdi, K. Schwarzburg, M. Stolterfoht, R. Eichberger, R. van de Krol, D. Friedrich, H. Hempel, PRX Energy 1, 023008 (2022)

[3] U. Björksten, J. Moser and M. Grätzel, Chem. Mater. 6, 858 (1994)

[4] M. M. Hawkeye, M. T. Taschuk and M. J. Brett, “Glancing Angle Deposition of Thin Films”, John Wiley & Sons, Ltd., Chichester, UK (2014).

[5] M. Caretti, E. Mensi, R.-A. Kessler, L. Lazouni, B. Goldman, L. Carbone, S. Nussbaum, R. A. Wells, H. Johnson, E. Rideau, J.-h. Yum, K. Sivula, Adv. Mater. 35, 2208740 (2023)
Studies of Hydrogen Desorption in Graphite Using Extreme Time Scale Chronoamperometry in a Molten Salt Environment
Authors: Bruni Colton , Vergari Lorenzo , Williams Haley , Scarlat Raluca O.
Published: August 2024

Controlling tritium is a major issue in developing nuclear reactors which employ molten salts; to aid this, we must understand tritium retention in these reactors. An important factor that must be considered for tritium retention is the effect the molten salt environment has on the interactions between tritium and the graphite moderator. Traditionally, Thermal Desorption Spectroscopy (TDS) is used to study the adsorption of hydrogen and its isotopes onto graphite; however, this is done in a vacuum at a constant heating rate to remove desorbed hydrogen where the gas is then measured for hydrogen gas concentration vs. temperature. To test in a molten salt environment, a method is needed to create a concentration gradient to drive diffusion of hydrogen to the surface of the graphite since a vacuum cannot be applied. This can be done electrochemically using a graphite working electrode submerged in salt by applying a constant oxidizing potential. Desorbed hydrogen gas is oxidized by this potential on the surface of the graphite, creating a concentration gradient which continuously drives diffusion as the graphite and salt is heated. This technique, known as Electrochemical Thermal Desorption Spectroscopy (ETDS) can be used to study tritium interactions with graphite in molten salt using hydrogen as a surrogate.

Previous attempts of ETDS used chronoamperometry with a constant heating rate to determine current peaks and relate them to hydrogen desorption peaks from various traps in graphite identified in TDS literature. The largest problem facing this previous work was the contribution to measured current from sources other than hydrogen oxidation at the surface. Work has been done to use a “blank” sample of graphite to run heated chronoamperometry and act as a baseline to subtract from the “charged” sample data to find current contributions only from hydrogen oxidation. Additionally, characterization of the salt is being done to determine a theoretical background current based on the kinetics of possible reactions and the effects of overpotential, concentration and high temperature.

Current challenges facing ETDS development are being studied. In this work, we examine the contributions of background reactions to measured current, as well as current contributions due to the oxidation of hydrogen within the electrode rather than at the surface. The answers to these questions will increase signal to noise ratios of ETDS, allowing the technique to extract valuable kinetic parameters of hydrogen interactions and quantify hydrogen in graphite in a molten salt environment.
Cyclic Electrogravimetry Reveals Details of Copper Electrodeposition in the Presence of Additives
Authors: Leppin Christian , Langhoff Arne , Johannsmann Diethelm
Published: August 2024

Copper electroplating was studied based on cyclic voltammetry combined with a new type of acoustic microgravimetry. The instrument operates similarly to a quartz crystal microbalance with dissipation monitoring (EQCM-D), meaning that it reports shifts in resonance frequency, Δf, and half bandwidth, ΔΓ, on several overtones. Compared to the existing instruments, the time resolution was improved by a factor of 10 down to 10 ms using multifrequency lockin amplification. The frequency noise after accumulation was reduced below 10 mHz ≙ 0.12 ng/cm2 ≙ 0.14 pm (assuming ρ = 8.96 g/cm3) by modulating the electrode potential and averaging of Δf and ΔΓ. Mostly, Δf and ΔΓ are in line with the Sauerbrey prediction (Δf/n
≈const. and ΔΓ/n < -Δf/nwith n the overtone order). Small unsystematic deviations between overtones due to compressional wave effects are seen but no evidence for strong roughness or viscoelasticity. Further, the Faraday efficiency is almost unity, meaning that Δf is close to the expectations derived from the electrical current. The improved sensitivity enables to determine the time derivative of the frequency shift, which is equal to an apparent mass transfer rate that can be compared to the current directly. Again, small deviations are seen for bulk deposition and stripping. These go back to weak roughness effects most pronounced in the initial phase of bulk deposition and, also, to the presence of a Cu(I) intermediate during dissolution. When adding benzotriazole (BTA) or thiourea (TU) as plating additives, the gravimetric and the voltammetric response changes. For BTA, the deviations between mass transfer rate and current vanish indicative of decreased roughness. For TU additional features appear, related to a potential-dependent adsorption of TU and to increased underpotential deposition (UPD). In the presence of TU, the electrode-electrolyte interface displays viscoelasticity, evident by the bandwidth increases during deposition.[1]

Caption: Currents, time derivatives of the frequency shift, and bandwidth shift obtained during copper electrodeposition without additives (A), in the presence of 10 µM benzotriazole (B), and in the presence of 10 µM thiourea (C). Reprinted with permission from Reference [1].

References

[1] Leppin, C.; Langhoff, A.; Höfft, O.; Johannsmann, D. A Modulation QCM Applied to Copper Electrodeposition and Stripping. Electroanalysis
2021, 33 (12), 2529–253.

Figure 1
Understanding the Role of Corrosion and Reactive Oxygen Species in Electrochemical Ozone Production on Nickel and Antimony Doped Tin Oxide
Authors: Alaufey Rayan , Tang Maureen H. , Keith John , Zhao Lingyan , Wood Ezra , Lindsay Andrew , Siboonruang Tana
Published: August 2024

Electrochemical ozone production (EOP), a six-electron reaction, offers promising green applications for water disinfection and organic synthesis. Nickel and antimony-doped tin oxide (Ni/Sb-SnO2, NATO) electrodes are known to be active for EOP. Still, the mechanism of NATO's selectivity and activity and the origin of its instability need to be clarified. We combine electrochemistry, spectroscopic detection of reactive oxygen species (ROS) using selective chemical probes, oxygen anion chemical ionization mass spectrometry (CIMS), and density-functional theory (DFT) simulations to identify the reaction mechanism and investigate the role of corrosion and homogenous reactive oxygen species in EOP on NATO electrodes. We identify hydrogen peroxide as a critical reaction intermediate. Our results suggest that the presence of nickel in NATO enables the catalysis of hydrogen peroxide to hydroperoxyl radicals, which subsequently undergo oxidation to produce ozone. The isotopic makeup of products shows that water is the primary source of ozone, but it also contains oxygen from the metal oxide lattice. The change in the isotopic generation pattern of ozone suggests that NATO catalysts corrode irreversibly, and the lattice oxygen is not regenerated, explaining NATO's instability.
(Digital Presentation) The Effects of Heat Treatment on Electroreduction of Tungsten (VI) Oxide
Authors: Medvezhynska Olha , Kuleshov Serhii , Omel'chuk Anatoliy
Published: August 2024

According to the classic scheme of the FFC Cambridge process, oxides of refractory metals are reduced in the solid state. Before electrolysis, oxides are shaped into cylindrical preforms and annealed at high-temperatures (~1000 °С). Therefore, the purpose of this study is to establish the effect of heat treatment of the initial sample of tungsten trioxide on its electrochemical reduction on a solid cathode in a CaCl2–NaCl melt.

There are two types of tablets (preforms) were used for research: non-sintered (only compressed) WO3 and annealed at a temperature of 1000 °C. The surface of a pelletized tungsten trioxide sample without sintering is characterized by a uniform distribution of particles, shown in the SEM image (Fig. a). The particles agglomeration is characteristic for the sample WO3 after heat treatment (1000 °С) (Fig. b), which leads to a decrease in the area and an increase in the size of the voids. The unsintered sample has a larger surface area between the particles due to their dispersed state, which facilitates the penetration of the melt compared to the annealed sample.

Electrochemical reduction of pressed WO3 samples (d=0.8 cm, h=0.15±0.20 cm, m=0.45–0.50 g) was carried out under galvanostatic conditions (800 °С) with using steel as the cathode and graphite as the anode. It was established that preliminary heat treatment of WO3 does not contribute to its electrochemical reduction. After applying 1.20 A·h of electricity, the porous granules of unsintered WO3 were completely transformed into metallic tungsten (W), which is shown in Fig. c, line 1. However, sintered samples after electrolysis (quantity of electricity is 1.42 A·h) reduced only partially: W – 74.1%; CaWO4 – 25.9% (Fig. c, line. 2).

The results show that the reduction occurs more intensively in samples with more micropores, through which mass transfer occurs at the phase interface: tungsten compound to be reduced molten electrolyte mixture. That is why in the unsintered WO3 sample, the electrochemical reduction is faster. It can be assumed that the degree of reduction of WO3 on a solid electrode in CaCl2–NaCl also depends on its crystal structure. The annealed sample (tetragonal structure) is less susceptible to electrochemical reduction compared to the unannealed sample of tungsten trioxide (monoclinic structure). This is due to the fact that tetragonal WO3 (above 740 °C) is resistant to chemical attack, a poor conductor of electricity and has a low surface area. Monoclinic WO3 (from 17 to 330 °C) is more reactive, a better conductor of electricity and has a higher surface area.

Figure 1
(Digital Presentation) The Influence of Particle Size on Electrophotocatalytic Properties of Tungsten Trioxide Photoanodes
Authors: Chittoory Valli Kamala Laxmi Ramya , Dzik Petr , Sanak Tomas , Bartoš Radim , Králová Marcela , Vesely Micheal
Published: August 2024

The need for advanced wastewater treatment technologies has been highlighted owing to the widespread contamination of water sources with toxic and persistent organic chemicals. Thin films of tungsten (VI) oxide (WO3) were prepared by spin-coating and meyer rod coating nanoparticulate dispersions following a top-down approach through ball milling. The morphological properties of the layers were investigated by profilometry. The results showed that the surface area increased with the increase in milling time and for 96 hours sample it showed a nine-fold increase compared to commercial tungsten (VI) oxide powder. The electron microscopic images provided insight into the change in particle size and layer texture which comply with the morphological changes observed by profilometry. The influence of the particle size on the charge generation efficiency was investigated using photoanodes prepared from the studied suspensions. Two distinct formulations of different particle sizes were mixed in variable ratios, and we showed that multimodal coatings exhibit larger photocurrents than monomodal coatings. The main contribution of this work can be found in the economically inexpensive method of preparing thin films WO3.
Reconstructing the Pseudo-2-Dimensional (p2D) Model in Comsol Multiphysics Using Mathematical Interfaces
Authors: Mishra Lubhani , Jang Taejin , Garrick Taylor R. , Subramanian Venkat R.
Published: August 2024

The classic ‘pseudo-2-dimensional’ (p2D) model of Newman and co-workers (also known as the DFN model), with its different efficient implementations, is the state-of-the-art physics-based electrochemical model for lithium-ion batteries. COMSOL Multiphysics (COMSOL) is a popular modeling software for multiphysics simulations, and its Battery Design Module for Li-ion batteries is widely used in the battery modeling community. This work presents a step-wise model development for reconstructing the detailed p2D model equations. This includes variable model parameters and weak-form implementation for the solid-phase diffusion, eliminating the need for non-local couplings and approximations for modeling the pseudo radial-dimension in the solid-phase.

To model and understand the effect of capacity degradation on lithium-ion cells, the battery models in COMSOL need to incorporate additional degradation mechanisms. In this work, we have followed the approach of equation-based modeling in COMSOL, which enables us to formulate the p2D model using the mathematical PDE interfaces. This approach provides us with a lot of flexibility in terms of battery degradation model formulation and helps develop a clearer understanding of the p2D model equation in light of the assumptions involved.

The steps in the model development involved writing the conservation equations in the generic mathematics interfaces coupled with the additional equations for the degradation mechanisms. The efforts were centered on developing cycling simulations based on Events for practically relevant operating conditions. This custom model was validated against the results from COMSOL’s Battery Interface, in-house codes, and baseline cycle data from the experiments and further developed as a physicochemical degradation model for automotive, large-format Lithium-ion batteries.

This equation-based COMSOL model with cycling works without the requirement for Battery Design Module, LiveLink and Application Builder and can be adopted for a variety of electrochemical modeling applications by the electrochemical modeling community.
Phase-Field Model of SEI Formation in Li-Metal Batteries
Authors: Ji Yanzhou , Zhang Kena , Wu Qisheng , Qi Yue , Chen Long-Qing
Published: August 2024

The formation of solid electrolyte interphase (SEI) is critical to the overall performance of lithium batteries. Here we have developed a rather comprehensive phase-field model for predicting the formation and growth of SEI, taking into account of multiple electrochemical/chemical reaction pathways leading to multiple SEI reaction products, diffusion of ionic and molecular species, and electron tunneling. All the SEI products are treated stoichiometric compounds without the typical approximation of parabolic composition dependence in almost all existing phase-field models involving stoichiometric compounds, allowing the direct connection between the phase-field model and atomistic calculations without further approximation. As a model system, we consider a 1-D prototypical half-cell with Li metal anode, liquid ethylene carbonate (EC) electrolyte with 1 molar (M) LiPF6, and SEI products Li2BDC and Li2CO3 under the open-circuit condition. The reduction potentials and activation barriers of the reactions are determined using atomistic simulations while the diffusivities of Li+ and EC in the bulk electrolyte are obtained by performing molecular dynamics simulations. The phase-field simulation is capable of predicting the evolution behavior of SEI products within a wide range of time scales from nanoseconds to a few seconds. It reveals that: (i) a porous Li2BDC layer forms at the anode/electrolyte interface and grows to a stable thickness of several tens of nanometers within ~20 μs; (ii) a porous Li2CO3 layer forms between anode and Li2BDC and grows to ~10 nm by partially consuming the existing Li2BDC layer within ~33 μs; and (iii) Li2CO3 forms a dense layer by filling the pores within ~20 ms. The stage (i) and (ii) are dominated by Li+ diffusion kinetics whereas stage (iii) is controlled by the reaction kinetics. The general computational framework can be extended and applied to the simultaneous evolution of Li-metal deposition and stripping and the SEI evolution.
Maximizing Energy Density of Full-Cell Storage Devices Using Topology Optimization
Authors: Roy Thomas , Li Hanyu , Brady Nicholas , Bucci Giovanna , Cross Nicholas R. , Ehlinger Victoria Marie , Lin Tiras Y , Salazar de Troya Miguel A , Tortorelli Daniel , Worsley Marcus Andre
Published: August 2024

Typical porous electrodes are homogeneous, stochastic collections of micron-scale particles offering few opportunities for engineering higher performance. To leverage recent breakthroughs in advanced and additive manufacturing, we use topology optimization to design porous electrodes for electrochemical energy storage devices such as batteries and supercapacitors. Energy density is maximized, leading to non-trivial geometries that outperform monolithic electrodes. These geometries facilitate ionic transport and lead to better electrode utilization and energy efficiency. We consider simultaneous optimization of cathode and anode, which can lead to interdigitated/interpenetrating designs.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was supported by the LLNL-LDRD program under project number 23-SI-002 and 20-ERD-019.

LLNL-ABS-857450
Degradation Studies of Fuel Cell Cathode Catalyst Layers Using Machine Learning
Authors: Sanumi Oluwafemi Joseph , Schneider Patrick , Batool Mariah , Ortiz Richard , Singh Rajveer , Gerteisen Dietmar , Beykal Burcu , Zamel Nada , Jankovic Jasna
Published: August 2024

Fuel cells are a promising technology that has the potential to significantly revolutionize the energy sector by providing clean and sustainable sources of power for transportation, aerospace, and electricity applications. However, optimizing the performance of these devices remains a significant challenge as it largely depends on the catalyst layer in the electrodes of these devices, composed of carbon-supported Pt nanoparticle catalyst (Pt/C), perflurosulfonic acid (PFSA), ionomer binder, and a solvent. The catalyst layer design and operation require extensive knowledge of complex physical and chemical processes especially when achieving a low (<0.1 mgcm-2) Pt loading.

Furthermore, the degradation of fuel cells is usually associated with either mechanical and/or electrochemical processes of the catalyst layer during operations, ultimately resulting in performance loss. While combinations of factors are responsible for the degradation of the catalyst layer in the fuel cell electrodes, it is still challenging to evaluate which factor contributes the most to the degradation of the catalyst layer.

Machine learning algorithms, being powerful tools for predicting and optimizing the behavior of systems can be used to model complex processes, identify optimal operating compositions, and conditions, and reduce the laborious time and cost required for experimentation. They can be used to analyze data obtained from various experiments to identify patterns, trends, and anomalies. In this study, machine learning algorithms are employed for the prediction of catalyst layer degradation. Furthermore, an assessment of feature importance is conducted, elucidating the relative contributions of individual features to the degradation of catalyst layers. Leveraging on machine learning, we can develop an efficient, reliable, and cost-effective fuel cell system.
(Invited) Computational Framework and Insights Towards Electrolyte Design for Redox Flow Batteries
Authors: Mayes Maricris L. , Visayas Benjoe Rey B. , Abdulai Ahmed , Agar Ertan , Cappillino Patrick J.
Published: August 2024

Achieving a fully renewable energy future requires the development of grid-scale energy storage technologies, and non-aqueous redox flow batteries (NRFBs) hold considerable potential.1 However, the redox-active materials (RAMs) currently in consideration as lead candidates for NRFBs exhibit shortcomings, including low solubility, impaired transport properties, and low reduction potentials. Utilizing theory and computation is invaluable in predicting the structure-property relationship of RAM as NRFB active materials. The numerous components within NRFB electrolytes, spanning solvents, active materials, and supporting salts, suggest that material discovery could experience a substantial acceleration through computational and machine-learning approaches.

This presentation will provide a progress update on our efforts towards a computational framework involving quantum mechanical (QM), molecular dynamics (MD), and machine learning methods to predict fundamental chemical and physicochemical properties of redox-active materials for energy storage systems. We used an extremely stable, bio-inspired vanadium(4+) bis-hydroxyiminodiacetic acid (VBH) as the scaffold to explore the large parameter space of NRFB systems.2–4 First, we show our framework based on density functional theory (DFT) for calculating solubilities, incorporating both lattice and solvation energies, that can be calibrated and used with synthetic verifications. We found that lattice free energy, which has previously been neglected, has a significant role in tuning electrolyte solubility. Second, we describe our MD simulations on the concentration and composition dependence of transport properties, such as viscosity, using DFT-derived force field bonded parameters for the novel [VBH]2- anion to understand the interactions between the ions and the solvent. Third, we demonstrate that QM molecular design could finely adjust the reduction potential. These fundamental investigations would offer insights into electrolyte design and how molecular properties dictate the macroscopic properties that contribute to specific performance aspects of advanced battery electrolytes.

1 Y. Huang, S. Gu, Y. Yan and S. F. Y. Li, Current Opinion in Chemical Engineering, 2015, 8, 105–113.

2 H. Huang, R. Howland, E. Agar, M. Nourani, J. A. Golen and P. J. Cappillino, J. Mater. Chem. A, 2017, 5, 11586–11591.

3 S. K. Pahari, T. C. Gokoglan, B. R. B. Visayas, J. Woehl, J. A. Golen, R. Howland, M. L. Mayes, E. Agar and P. J. Cappillino, RSC Adv., 2021, 11, 5432–5443.

4 B. R. B. Visayas, S. K. Pahari, T. C. Gokoglan, J. A. Golen, E. Agar, P. J. Cappillino and M. L. Mayes, Chem. Sci., 2021, 12, 15892–15907.
(Invited) Theoretical Insights in the Design of Active Sites and Environments to Guide Electrocatalytic Transformations for Sustainable Energy and Chemicals Production
Authors: Neurock Matthew
Published: August 2024

Future strategies for sustainable energy and chemicals production will undoubtedly require the design of electrocatalytic systems that actively and selectively convert wastes such as CO2 emissions and biomass into chemicals and fuels. While enzymes elegantly integrate highly active centers together with adaptive nanoscale environments to selectively control catalytic transformations, they are limited industrially by their durability. The design of robust electrocatalytic materials and systems that can mimic the activity and selectivity of enzymes, however, has been hindered by our understanding of how such transformations proceed over inorganic materials and complex environments. Advances in theory, simulations, spectroscopy and characterization begin to allow us to track the molecular transformations and how they proceed in electrocatalytic systems at specific sites and within particular environments. This information can enable the design of unique surface ensembles and nanoscale environments that can efficiently catalyze specific molecular transformations. Herein we develop and use ab initio methods to examine the influence of anions, cations and solvents in complex electrochemical environments to carry out selective molecular transformations. More specifically, we discuss the electrocatalytic reduction of CO2 and aromatics to valuable chemical and pharmaceutical intermediates. We draw direct analogies between the elementary processes that govern these seemingly different systems. We explore the manipulation of different solvents (ionic liquids and water), electrolytes (effects of anions and cations), pH as well as different metals and electrochemical potential to drive the formation of 3D environments that aid in controlling these transformations. We expand the discussion to selective oxidation reactions and examine the design of mediators to enable the selective C-H bond activation.
Accelerating Battery Research through Atomistic and Multi-Scale Computational Chemistry
Authors: Goumans Theodorus P.M. , Onofrio Nicolas
Published: August 2024

Computational screening and advanced insights from simulations will help you develop new and improved battery materials quicker and with less resources. We will discuss our efforts to help researchers to do that with the Amsterdam Modeling Suite (AMS). The AMS framework separates the atomistic engines (DFT, DFTB, ReaxFF, ML potentials) from the driver, which enables the exploration of potential energy surfaces (PESs), mechanical, and electronic properties at several levels of theory. The central AMS driver supports advanced PES explorations, molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC), based on energies and forces from the engines.

With this driver-engine set up, you can calculate and predict relevant processes and properties for battery materials. We will discuss recent developments and examples using:

DFT and GW with COSMO-RS for accurate electrode and redox potentials

(e)ReaxFF for discharge processes including diffusion, discharge profiles, electrolyte degradation, and solid-electrolyte interface formation

polarizable force fields for accurate viscosities and charge mobilities

pre-parametrized and on-the-fly machine learning potentials for diffusion barriers, intercalation potentials, and reactive processes

kinetic Monte Carlo to describe mesoscale processes such as dendrite formation

We will also discuss where we envision future ML and multi-scale developments to accelerate materials discovery, particularly focusing on battery applications.

Figure 1