bluuebunny/crossref_metadata_2025 huggingface dataset:
Catalyst Support Interactions of Highly Active Nife-LDH Towards the Implementation in Photoelectrochemical and Sea-Water Based Water Splitting Technologies
Authors: Buchheister Paul Wolfgang , Gort Christopher , Klingenhof Malte , Kaiser Bernhard , Strasser Peter
Published: September 2023

For the implementation in photoelectrochemical (PEC) and sea-water based water splitting devices it is of utmost importance to find stable substrates that do not degrade under application related potentials and illumination. While PEC devices incorporate an absorber that has to be protected from the harsh conditions in the electrolyte, the prevalence of Cl- ions in sea-water based water splitting devices leads to corrosion of most metallic substrates under application related potentials. Catalyst coated TiO2 substrates are therefore used as protection layers in PEC devices, while titanium porous transport layers show great stability in anionic exchange membrane sea-water splitting devices.

In this study we investigated the interaction between state-of-the-art NiFe-LDH as a catalyst for the OER and titanium substrates. It was shown that the activity of NiFe-LDH on bare Ti/TiOx substrates was very poor. Through the incorporation of thin metal interlayers (Au, Ni) an increase in current density by two orders of magnitude could be observed. Through detailed XPS measurements before and after electrochemical activation of the electrodes we were able to show an improved transformation of the as prepared catalyst into the highly active (oxo)hydroxide phase for the gold and nickel sputtered titanium electrodes. An accelerated stress test performed on these electrodes showed a stable behavior for most electrode assemblies, with Nickel interlayers showing great promise for PEC devices. From our experiments we exclude a pure conductivity enhancement as possible explanation, but instead propose an additional change in the local atomic and electronic structure at the metal-support and metal-catalyst interfaces.
A Conversion Type Iron Anode for High-Areal-Capacity Hybrid Redox Flow Batteries
Authors: SHI Yang , Lu Yi-Chun
Published: September 2023

Redox flow battery (RFB) is one of the most promising technologies for energy storage owing to its advantages of high safety, high efficiency, and low cost.1 Hybrid RFBs such as Zn-based RFBs offer a much higher energy density compared to all liquid RFBs. However, they rely on metal dissolution/deposition electrodes, which suffer from severe dendrite issues and poor reversibility, especially at high areal capacity and high current density. These inherent challenges of metal electrodes preclude their practical deployment for large-scale and long-duration energy storage applications.

To break from this intrinsic limitation, in this work, we exploited a high-loading conversion electrodes to replace metal deposition electrodes to achieve high cycling stability at high areal capacity/current density for hybrid RFBs. With this strategy, using Fe3O4/Fe(OH)2 conversion negative electrode as an example coupling with ferricyanide/ferrocyanide positive electrode, we demonstrated conversion type all-iron hybrid RFBs with an unprecedented high cycling areal capacity of 126.6 mAh cm–2 at 50 mA cm–2 for 200 cycles (1000 hours) and 215 mAh cm–2 at 60 mA cm–2 for 100 cycles (700 hours) without capacity decay.2 The conversion electrode eliminates the dendrite issues and limitations on metal areal capacity, demonstrating unprecedented high cycling areal capacity and current density compared to conventional dissolution/deposition zinc metal negative electrode. We will discuss the compositional/morphological stability of the Fe3O4/Fe(OH)2 conversion iron negative electrode during the hybrid RFB operation and the techno-economic analysis of developed conversion type all-iron hybrid RFB for practical applications.

Acknowledgment:

The work described herein was supported by a grant from the Research Grant Council (RGC) of the Hong Kong Special Administrative Region, China (project no. C1002-21G).

Reference:

(1) Yao, Y. X.; Lei, J. F.; Shi, Y.; Ai, F.; Lu, Y. C. Assessment methods and performance metrics for redox flow batteries. Nat. Energy
2021,
6 (6), 582.

(2) Shi, Y.; Wang, Z.; Yao, Y.; Wang, W.; Lu, Y.-C. High-Areal-Capacity Conversion Type Iron-Based Hybrid Redox Flow Batteries. Energy Environ. Sci.
2021, 10.1039/D1EE02258J.
Development of Cost-Effective Membranes for Redox-Flow Batteries
Authors: Yang Guang , Lehmann Michelle , Self Ethan , Sacci Robert L , Saito Tomonori , Nanda Jagjit
Published: September 2023

Developing long-duration energy storage (LDES) systems is key to promoting the penetration of intermittent energy storage, such as solar and wind into the electric grid. DOE’s Long Duration Storage Shot establishes a target to reduce the cost of grid-scale energy storage by 90% for systems with durations of >10 hours. Non-aqueous RFBs (non-aqueous RFB) using earth-abundant materials are promising to fulfill this target. A key bottleneck to keeping RFB from market penetration is the lack of high-performance and cost-effective membranes. Membranes represent the most critical component in non-aqueous RFB, and they are decisive to the cell stack performance and cost. For example, the ionic conductivity of the membrane determines the power density of the RFBs, while ion selectivity and solvent uptake govern non-aqueous RFB cycle life. Herein, we will present recent progress in our team on the membrane development for the non-aqueous flow batteries.

The ionic conductivity - mechanical strength tradeoff is a long-standing challenge for all polymer electrolyte development. In a redox flow battery, solvent uptake promotes membrane ionic conductivity but decreases its storage modulus due to the increased polymer chain relaxation. Two strategies are found effective to alleviate such a tradeoff i) selective plasticization of the ion-conductive block such as poly(ethylene oxide) (PEO) in a polystyrene (PS)− PEO−PS block copolymer (SEO) electroconductivity by glyme-type of solvent, and ii) enhancement of the membrane mechanical strength by creating hydrogen and ionic bonds between the polymer matrix and the inorganic scaffold. Mitigating redox-active species crossover poses another challenge in membrane design. We show that the cation exchanged single ion conducting membrane can effectively decrease the crossover of the polysulfide species in a Na metal – polysulfide hybrid flow battery, which promotes the RFB capacity retention, Columbia efficiency, and cycle life benchmarked to a commercial porous membrane.

Acknowledgment

This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the U.S. Department of Energy through the Energy Storage Program led by Dr. Imre Gyuk, in the Office of Electricity.
Sterically Bulky Asymmetric Benzophenone Derivatives as Negolytes in a Non-Aqueous Redox Flow Battery
Authors: Jesse Kate Ashley , Diaz-Abad Sergio , Maurya Sandip , Davis Benjamin L
Published: September 2023

To increase renewable energy generation to the electrical grid, intermittent energy sources, such as wind and solar energy, need a long-term, large scale energy storage method. Redox flow batteries (RFB) are an attractive solution as they allow for long term storage in various redox states of an organic or inorganic compound. The ideal redox-active compound for a RFB should have a high energy density, which can be achieved through a large potential difference in redox events, high concentration of charge carrier, or by increasing the number of electrons transferred during a given redox event. In particular, nonaqueous RFB (NRFB) are promising for building a system with a large potential difference for redox events due the large electrochemical solvent window (~5 V for acetonitrile) as compared to water (~2 V). While metal complexes featuring redox active ligands have been thoroughly investigated as carriers in NRFBs, they are often too expensive for widespread use. This has led to increasing interest in organic carriers. Benzophenone is a promising candidate for an organic negolyte due to its high solubility in acetonitrile and the presence of a reversible reduction at -2.1 V vs. Ag/Ag+. Unfortunately, the durability of benzophenone during cycling is low. Here, we discuss the degradation products of benzophenone during cycling and show how the incorporation of sterically bulky groups ortho to the benzophenone carbonyl improves durability. We then evaluate the utility of these benzophenone derivatives as negolytes in a NRFB flow cell.
Molecular Engineering for Redox-Flow Batteries Designed for Long-Duration Energy Storage
Authors: Helms Brett
Published: September 2023

Electrochemical energy storage solutions for long-duration use-cases should feature active materials with exceptional stability in their charged state. In this presentation, I will discuss how molecular engineering is a powerful toolbox for tailoring the properties of organic redox-active molecules used as active materials in redox-flow batteries, particularly long-term stability as a function of redox potential in electrolyte. Instability can come from a variety of fundamental physical phenomena in the flow cell: desolvation of charged active materials in the electrolyte over time, producing solids; disproportionation and other parasitic reactions, including those between actives and the electrolyte; degradation and fouling of polymer membranes in contact with highly oxidizing or highly reducing catholytes and anolytes, respectively. To manage these risks, I will offer potential solutions from the atomic to macromolecular scales in the active materials and polymer membranes, where there is vast opportunity to gain access to cell chemistries that meet target requirements for the technology. I will also offer a perspective on how to scale to meet cost targets set forth in the Long-Duration Energy Storage Grand Challenge and Technology Roadmap.
Higher Energy Density Mediated Lithium-Sulfur Flow Batteries
Authors: Meyerson Melissa L , Maraschky Adam M. , Small Leo J.
Published: September 2023

There is a need for safe, reliable, high-capacity storage for long duration energy storage. The low cost and high specific capacity of sulfur make Li-S batteries ideal for this purpose. However, sulfur has poor electrical conductivity and Li-S batteries are prone to polysulfide shuttling that decreases the battery life. Additionally, lithium metal cannot be cycled at high rates or dendritic growth is produced. We have previously addressed the issues with the S by combining aspects of a static Li-S battery with aspects of a redox targeting system and flow battery. With this system we demonstrated that fundamental Li-S chemistry and novel SEI engineering strategies can be adapted to the hybrid redox flow battery architecture, obviating the need for ion-selective membranes or flowing carbon additives, and offering a potential pathway for inexpensive, scalable, and safe MWh scale Li-S energy storage. Here we present two key improvements to the system: (i) scaled up sulfur loading from 2.5 mgs cm-2 to over 50 mgs cm-2 (increasing energy density), and (ii) increased current density from 0.5 mA cm-2 to 10 mA cm-2 (increasing power density). Additionally, we are able to assemble the battery in the discharged state, improving the safety and decreasing manufacturing costs.

To implement these improvements, we address the limitations due to the formation of dendrites on the Li metal anode. We first tested high surface area scaffolds in Swagelok cells to examine the effect of the increased effective surface area and seeding with lithiophilic materials like ZnO on Li metal deposition independent of the flow cell or S chemistry. Using a high effective surface area scaffold enabled increasing the applied current density from 0.5 mA cm-2 to 10 mA cm-2, increasing the cycling rate by 20x. Furthermore, the addition of a lithiophilic seed layer decreases the nucleation overpotential and encourages uniform Li electrodeposition. A tailored flow field also increases the uniformity of Li deposition on the anode by enhancing the uniformity of the catholyte flow velocity. These modifications are first evaluated separately and then combined in a mediated Li-S flow battery where cycling rate and capacity retention are compared against a traditional planar Li anode and open flow field.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Enhancing the Electrochemical Properties of the Layered-Type K0.4V2O5 Cathode Materials through Cationic Metal Substitution in K Sites
Authors: Oh Gwangeon , Hwang Jang-Yeon
Published: September 2023

Layered-type K0.4V2O5 have been widely investigated as cathode materials for potassium-ion batteries (PIBs) due to their high specific capacity. [1,2] However, sluggish intercalation kinetics of K ions into their crystal structure generally result in drastic capacity fading and poor power capability. [3] Here, we present significantly enhanced K-ion storage performances of the layered-type K0.4V2O5 cathode enabled by substitution of cationic metal for K-site. Density functional theory calculations data indicates that cationic metal prefer to occupy the K-site than transition metal layer. During charge and discharge process, inactive cationic metal acts as a pillar, thereby suppressing the irreversible phase transition and structural deterioration. In addition, cationic metal creates vacancies at k site, improving K-ion diffusion kinetics. Compared to K0.4V2O5, the modified cathode demonstrated the better cycling stability and power capability. A insitu X-ray diffraction and X-ray absorption near edge structure was used to verify role of cationic metal in improving electrochemical performance of the K0.4V2O5 cathode.

Deng, X. Niu, G. Ma, Z. Yang, L. Zeng, Y. Zhu, L. Guo. Layered Potassium Vanadate K0.5V2O5 as a Cathode Material for Nonaqueous Potassium Ion Batteries, Adv. Func. Mater. 28 (2018) 1800670.

Yang, Z. Liu, L. Deng, L. Tan, X. Niu, M. M. S. Sanad, L. Zeng, Y. Zhu. A Non-Topotactic Redox Reaction enabled K2V3O8 as a High Voltage Cathode Material for Potassium-Ion Batteries, Chem. Commun. 55 (2019) 14988–14991.

Q. Fu, A. Sarapulove, L. Zhu, G. Melinte, A. Missyul, E. Welter, X. Luo, M. Knapp, H. Ehrenberg, S. Dsoke. In Operando Study of Orthorhombic V2O5 as Positive Electrode Materials for K-Ion Batteries, J. Energy Chem. 62 (2021) 627–636.
A Structural Model for Transient Pt Oxidation during Fuel Cell Start-up Using Electrochemical X-Ray Photoelectron Spectroscopy
Authors: Nagra Hassan , Mom Rik , Knop-Gericke Axel
Published: September 2023

Potential spikes during the start-up (SU) and shutdown (SD) of fuel cells are a major cause of platinum (Pt) electrocatalyst degradation, which limits the lifetime of the device. The electrochemical oxidation of Pt that occurs on the cathode during the potential spikes plays a key role in this degradation process. However, the composition of the oxide species formed, as well as their role in catalyst dissolution remains unclear. In this study, we employ a special arrangement of XPS (X-ray Photoelectron Spectroscopy), in which the Pt electrocatalyst is covered by graphene, making the in situ examination of the Pt oxidation/reduction under wet conditions possible. We use this assembly to investigate oxidation state changes of Pt within fuel cell relevant potential window. We show that above 1.1 VRHE, a mixed Ptδ+/Pt2+/Pt4+ surface oxide is formed, with an average oxidation state that gradually increases as the potential is increased. By comparing a model based on the XPS data to the oxidation charge measured during potential spikes, we show that our description of Pt oxidation is also valid during the transient conditions of fuel cell SU/SD. This is due to the rapid Pt oxidation kinetics during the pulses. As a result of the irreversibility of Pt oxidation, some remnants of oxidized Pt remain at typical fuel cell operating potentials after a pulse.

Figure 1
Studying Crack Formation in Catalyst Layer Films for Proton Exchange Membrane Fuel Cells
Authors: Liu Jiawei , Plymill Austin , Blackburn Scott , Park Andrew M , Litster Shawn
Published: September 2023

The performance and durability of proton exchange membrane fuel cells (PEMFCs) can be affected by cracks formed in catalyst layers (CLs). While previous research has shown that CLs prepared with pre-commercial high oxygen permeability ionomer (HOPI) are more efficient and durable, they can lead to significantly more cracking features than CLs prepared with traditional perfluorosulfonic acid (PFSA) ionomer. Therefore, it is important to reduce cracking to further improve cathode performance, durability, and film quality. With this goal in mind, we analyzed ink drying and crack formation during the wet-film coating process via imaging with an optical microscope fixed above a film applicator. Transient quantitative crack growth studies were performed to evaluate the dynamic nature of the process. Alongside that, the crack density of post-coating films was quantified at higher resolutions using a compound microscope. Ink composition, Pt-based catalysts and relative humidity of drying environment were varied in order to understand which combinations resulted in fewer cracks.

This material is based upon work supported by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Fuel Cell Technologies Office, Award Number DE-EE0008822.
Effect of Gas-Phase Nitric Oxide Adsorption on ORR Activity of Fe-N-C Catalysts
Authors: Wang Xiaoping , Ferrandon Magali , Park Jae Hyung , Zeng Yachao , Wu Gang , Myers Deborah J.
Published: September 2023

Significant progress has been made in recent years in developing platinum group metal-free catalysts, particularly so-called Fe-N-C materials, for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells.1 However, further improvement in both activity and, especially, durability are still necessary for practical applications. One of the major factors that hinder the further enhancement of the catalysts is the lack of clear understanding of the nature of the active sites in the Fe-N-C catalysts due to the complexity of the Fe-N-C catalysts’ composition and structure. Gaseous nitric oxide was reported to be a suitable probe molecule that can bond to Fe and impede the ORR of the Fe-N-C catalysts.2,3 In this work, the effect of nitric oxide gas-phase adsorption on Fe-N-C catalyst redox feature and ORR activity for a variety of Fe-N-C catalysts from different origin will be investigated. The implication of these results on the nature of the ORR active sites of the Fe-N-C catalysts will be discussed.

Acknowledgements

This work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). This work was partially authored by Argonne, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.

References

X.X. Wang, M.T. Swihart, and G. Wu, "Achievements, challenges, and perspectives on cathode catalysts in proton exchange membrane fuel cells for transportation", Nature Catalysis, 2 (2019) 578-589.

J.L. Kneebone, et al., "A Combined Probe-Molecule, Mossbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst", J. Phys. Chem. C 121 (2017) 16283-16290.

P. Boldrin, D. Malko, A. Mehmood, U.I. Kramm, S. Wagner, S. Paul, N. Weidler, A. Kucernak, “Deactivation, reactivation and super-activation of Fe-N/C oxygen reduction electrocatalysts: Gas sorption, physical and electrochemical investigation using NO and O2”, Applied Catalysis B: Environmental 292 (2021) 120169.
Fundamental Insight into Phenyl-Free Polynorbornene Ionomers Enables High Performance Anion Exchange Membrane Fuel Cells
Authors: Leonard Daniel , Lehmann Michelle , Matanovic Ivana , Fujimoto Cy , Saito Tomonori , Kim Yu Seung
Published: September 2023

Anion exchange membrane fuel cells (AEMFCs) are seen as a possible successor to proton exchange membrane fuel cell technologies. A major motivation behind AEMFC development is the potential to use less costly materials, such as non-platinum group metal catalysts, thus reducing the stack cost. Anion exchange ionomers (AEIs) are polymers that facilitate ion transport in the catalyst layer play and a critical role in the performance of fuel cells. In fact, cell performance is profoundly affected by fundamental interactions between the catalyst surface and the AEI. Two such interactions are of particular importance: phenyl adsorption on hydrogen oxidation catalysts and electrochemical oxidation of phenyl moieties on oxygen evolution catalysts. Both are detrimental to an alkaline device’s performance and durability.

We compared the adsorption energy of phenyl-containing ionomers for implementing phenyl-free ionomers. Density functional theory calculations indicated that the norbornane fragment has minimal adsorption energy on Pt(111) due to the absence of aromatic electrons. A soluble quaternized polynorbornene ionomer was prepared by vinyl addition polymerization. This ionomer enables high performance in fuel cells, (peak power density > 2 W cm-2), proving the advantage of the phenyl-free structure. This study establishes the phenyl adsorption energy-electrode performance relationship, highlighting the importance of material interactions between the catalysts and ionomers.
Stabilization of Platinum Catalyst Surface-Treated by Atomic Layer Deposition of Cobalt for Polymer Electrolyte Membrane Fuel Cells
Authors: Shim Jung Woo , Lee Yong Seok , Choi Yun Sung , Seo Beum Geun , Shim Joon Hyung
Published: September 2023

Polymer electrolyte membrane fuel cells (PEMFCs) are attracting attention as next-generation energy-conversion devices because they are environmentally friendly and have high energy-conversion efficiencies. A membrane electrode assembly (MEA), composed of an anode, membrane, and cathode, is the most important part of a PEMFC where electrochemical reactions occur. A Pt/C catalyst, wherein Pt is supported on a carbon, is used as the catalyst layer for the anode and cathode. However, as Pt is a precious metal, current research is focused on reducing its loading and improving durability of PEMFCs.

This study focused on improving the durability of catalysts by suppressing agglomeration, one of the degradation mechanisms of Pt catalysts. A protective layer of Co metal was deposited using the atomic layer deposition (ALD) process to improve the durability of catalysts. The ALD process is a type of chemical vapor deposition (CVD) process. This process is suitable for the PT/C catalyst as it allows for the deposition of a uniform thin film even on the porous catalyst layer. If the protective layer is thick, it may block the active site of the catalyst, resulting in decreased activity and reduced performance. However, ALD can form a thin protective layer because it can be controlled at the atomic level by adjusting the number of cycles. After fabricating a single cell using ALD Co-Pt/C as a catalyst for the cathode, The U.S. Department of Energy's electrocatalyst durability protocol was used for an accelerated degradation test (ADT). After Co-ALD was used as a cathode for 10 and 20 cycles, the active area of the Pt catalyst particles was reduced owing to the metal Co protective layer. The initial performance and electrochemical surface area (ECSA) of Co-ALD 10, 20 cycles decreased compared to the case of using Co-ALD 0 cycle. However, after ADT, the performance and ECSA reduction rate rather decreased, confirming that the co-protective layer through the plasma-enhanced atomic layer deposition (PEALD) process can improve the durability of the Pt/C catalyst. To identify the cause of the durability improvement, the cathode catalyst particles before and after ADT were compared through high resolution transmission electron microscopy (HR-TEM) analysis. As a result, in the HR-TEM images after ADT, the Pt catalyst particles were relatively uniformly distributed on the carbon support in the Co-Pt/C catalyst compared to Co-ALD 0 cycle. In addition, it was confirmed that the size of the Pt catalyst particles of Co-Pt/C was smaller than that of bare Pt/C (Co-ALD 0 cycle). It was concluded that when the Co protective layer was deposited on the Pt/C cathode, the protective layer suppressed the agglomeration of Pt catalyst particles, therefore, the increase in Pt particle size improved compared to the Co-ALD 0 cycle, and it was revealed that durability improved by suppressing catalyst degradation.
Discovery of New Fast Oxygen Conductors: Bi2MO4x (M= rare earth, X= halogen) Via Unsupervised Machine Learning
Authors: Meng Jun , Schultz Lane , Jacobs Ryan , Morgan Dane
Published: September 2023

Discovering new fast oxygen conductors is critical for developing many technologies, e.g., solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs), proton ceramic fuel cells (PCFCs), and solid oxide air batteries, particularly for operation at lower temperatures (below 700 ˚C). By leveraging unsupervised machine learning techniques and large databases of computed materials data (e.g., Materials Project), we are able to rapidly explore and screen for new materials with high oxygen mobility. In this work, we used unsupervised machine learning analysis applied to features extracted from the structure of materials and discovered a new structural class of vacancy-mediated oxygen conductor. To do this, we applied the K-nearest neighbor (k-NN) algorithm on all the approximately 62,000 oxygen-containing compounds in the Materials Project database, using X-ray diffraction (XRD) and pair distribution function (PDF) data to represent the structural features. The neighbors of reference known for good oxygen conductors were screened with criteria relating to material stability, synthesizability, and electronic property dissimilarity (to ensure a novel material) compared to the reference material. Starting with the best-known oxygen conductor, the fluorite-type material, we examined the materials list of its nearest neighbors and identified the Bi2MO4X (M=Rare-earth element, X= halogen element) structural family as a novel group of fast oxygen conductors. In particular, Bi2LaO4Cl is a layered bismuth oxyhalide crystallized in the space group P4/mmm, adopting a “triple fluorite” layer [Bi2LaO4]+, balanced by the anion Cl- layer. The stability and mobility of oxygen vacancy in Bi2LaO4Cl were studied using Density Functional Theory (DFT) methods. 2+ oxygen vacancy is the most thermodynamically favorable defect type. Ab initio and machine learning-trained interatomic potential molecular dynamic simulations were performed to study the high temperature oxygen mobility in Bi2LaO4Cl. The simulation results show that Bi2LaO4Cl presents an extremely low migration barrier of 0.14 +/- 0.03 eV below 700 ˚C, suggesting 10 to 20 times higher ionic conductivity compared to yttria-stabilized zirconia (YSZ). Bi2LaO4Cl is an insulator with a wide band gap of 2.65 eV, indicating that Bi2LaO4Cl may be a promising electrolyte material with high oxygen ion conductivity and low electronic conductivity. This work demonstrates the power of combining unsupervised machine learning approaches with large materials databases for finding new fast oxygen conductors.
Catalytic Activity of LnCo0.5Ni0.5O3-Δ (Ln = La, Pr, Nd) "Positrodes" on Ceramic Protonic Electrolytes
Authors: Kwati Leonard , Staykov Aleksandar , Wiff Juan Paulo , Meulenberg Wilhelm , Matsumoto Hiroshige
Published: September 2023

Proton-conducting solid-oxide electrolyzers and fuel cells represent viable, intermediate-temperature green energy conversion and storage technologies. Interest in this class of materials as electrolytes stems from their high ionic conductivity and inherent advantages in the gas flow configuration over traditional solid oxide cells in which the electrolyte is an oxygen ion conductor. However, their commercial viability has been hindered, in part, by the development of corresponding single-phase electrode components with mixed proton-electron conductivity and effective catalytic activity toward oxygen reduction and evolution reactions (ORR/OER). This paper investigates the origin of catalytic activity in LnCo0.5Ni0.5O3-δ (Ln=La, Pr and Nd) perovskites positrodes (positive electrode) by low energy-ion scattering (LEIS) and DFT studies. LEIS results reveal that La, Pr, and Pr cations dominate the outer atomic layer, with profound implications for catalytic activity. Whereas First principle calculations were performed using the plane-wave DFT method and hybrid HSE06 functional suggest, the catalytic activity and electronic properties depend on the valence shell structure of the Ln-site cation and their redox properties.

Acknowledgments

The authors gratefully acknowledge financial support through JSPS KAKENHI Grant-in-Aid for Scientific Research (C), No. 19K05672, NEDO (International collaboration work in the field of clean energy) JPNP20005, the International Institute for Carbon-Neutral Energy Research (I2CNER) sponsored by the World Premier International Research Center Initiative (WPI),
Iron-Doped Manganese Oxide (MnFeO2) for Efficient Potentiodynamic Investigation Toward Water-Splitting Application
Authors: Prajapati Jay , Srivastava Rishabh , Okwe Joseph , Kaur Kirandeep , Gupta Ram K.
Published: September 2023

Despite the huge progress that has been achieved in developing mixed metal oxides for remarkable and promising electrocatalysts towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), new cost-effective and non-toxic materials are much needed. A facile strategy was circumvented to embellish the callus 4e- transfer process of OER by achieving morphological enhancement and optimized electrical configuration. Herein, the different amount of iron (Fe) (2, 5, 10, and 12 at.%) was doped in manganese oxide (MnO2). Various characterization methods were subjected to study the phase, surface composition, chemical state, and structural improvement, using XRD, XPS, and SEM. Furthermore, experimental methods are employed to investigate a comprehensive understanding of the catalytic performance of the synthesized materials. Among all, Mn0.95Fe0.05O2 showed superior activity and endurance towards HER (79 mV of overpotential @ 10 mA/cm2 and Tafel slope of 182 mV/dec) and OER (278 mV of overpotential @ 10 mA/cm2 and Tafel slope of 44 mV/dec). It also exhibits impressive longevity over 24 h and the electrode material after a long run showed no further deterioration in electrochemical properties. Additionally, the aggrandized electrochemical active surface area corresponds to more active sites and produces H2 and O2 due to the significant roughness factor. Thus, Mn0.95Fe0.05O2 can serve as an effective bifunctional electrocatalyst for the water-splitting process.
Model Development and Optimization of a Solid Oxide Fuel Cell/Gas Turbine Hybrid Power System for Electric Aviation
Authors: Wilson Joshua , Leger Jeremy Joseph , Wang Yudong , Carroll John , Raush Jonathan , Swartz Scott , Daggett David , Singhal Subhash , Zhou Xiao-Dong
Published: September 2023

With countless global industries pledging and pursuing decarbonization targets set for the 2030 – 2050 timeframe, the aerospace industry faces many key challenges including reduction of greenhouse gas emissions, contrail abatement, and development/adoption of technologies with higher Fuel-to-Electricity (FTE) conversion efficiencies. One such technology identified as a potential fit for commercial aircraft is the solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system. Progress in system-level SOFC-GT modeling is critical to produce higher fidelity feasibility studies used to influence SOFC design and performance targets of the future. In this study, the first ProMax 5.0-based SOFC-GT model was developed, validated, and optimized. The impact of process configuration, balance-of-plant, and operating conditions were investigated. An optimal process design comprising 8 SOFC stacks and 7 Energy Storage and Power Generation (ESPG) modules with a total power output of > 7.0-MW and FTE conversion efficiencies of 73 – 76% is reported. Additionally, preliminary airplane architecture with the 7 onboard ESPG modules is presented to show the feasibility of future, hybrid electric airplane design.
Electrochemical C-N Coupling Reaction Mediated by π-Extended Haloarene Catalyst
Authors: Shida Naoki , Yoshinaga Shohei , Atobe Mahito
Published: September 2023

Hypervalent iodine is a useful reagent in synthetic organic chemistry,[1] but because these reagents are synthesized by reaction with stoichiometric amounts of oxidants, their large-scale use is associated with safety and environmental impact concerns. Hypervalent iodine can also be synthesized by electrochemical oxidation of the corresponding iodoarenes, and the electrochemically generated hypervalent iodine can be immediately reacted and used catalytically, i.e., as an electrochemical mediator, to enable a reaction system that is safe and generates little waste.[2]

The use of hypervalent iodine as an electrochemical mediator has been reported previously, [3,4] but the number is still limited. In addition, no quantitative kinetic analysis of catalytic reactions has ever been performed. The presenters hypothesized that the following two issues are responsible for this situation: (i) the high oxidation potential of iodoarenes makes their selective oxidation difficult, and (ii) the instability of the radical cation.

In this study, we designed and synthesized a novel π-extended iodoarene 1, and developed it as an efficient electrochemical mediator (Figure 1). The extended π system realized stabilization of the radical cation intermediate, as well as lowering the oxidation potential. Electrochemical oxidations of various N-Boc-2-aminobiphenyl analogues (2) were performed, and successfully gave cyclized product 3 in high yield in the presence of a base. Kinetic analysis of the electrocatalytic process based on Foot-of-the-Wave analysis (FOWA)[5] was also investigated.[6] In addition, we have also investigated the electrocatalytic reaction and kintetics using mediators with bromo- and chloro-anthracene structures to uncover the structure-reactivity relationship of haloarene mediators.

[1] A. Yoshimura, V. V. Zhdankin, Chem. Rev., 2016, 116, 3328–3435. [2] M. Elsherbini, T. Wirth, Chem. Eur. J.
2018, 24, 13399–13407. [3] T. Fuchigami, T. Fujita, J. Org. Chem.
1994
, 59, 7190-7192. [4] A. Maity, B. L. Frey, N. D. Hoskinson, D. C. Powers, J. Am. Chem. Soc.
2020, 142, 4990−4995. [5] C. Costentin, S. Drouet, M. Robert, J.-M. Savéant, J. Am. Chem. Soc.
2012, 134, 11235–11242. [6] S. Yoshinaga, M. Atobe, N. Shida, ChemRxiv, 2022, DOI: 10.26434/chemrxiv-2022-sggqd.
Electrochemical Cycloaddition Reactions of Alkene Radical Cations – a Route Towards Cyclopropanes and Cyclobutanes
Authors: Rybickajasinska Katarzyna , Szeptuch Zuzanna , Kubiszewski Hubert , Kowaluk Agnieszka
Published: September 2023

New methods to promote single-electron transfer reactions play an increasingly important role in driving modern organic chemistry. Significant advances have been made in the field of photoredox catalysis1 and synthetic organic electrochemistry2 to expand the utility of radicals in organic synthesis.3 While the initial developments in synthetic organic electrochemistry date as far back as the early 19th century, only recently has it undergone an explosive revival and it is now an important part of synthetic organic chemistry.4 Undeniably, it provides a green alternative to known and new reactive intermediates by the promotion of organic reactions under mild conditions without the necessity for excessive amounts of hazardous and wasteful oxidants and reductants, metals4 or catalysts, making chemical synthesis highly atom economical.5

Our work describes mild and efficient electrochemical methods for [2+1] and [2+2] cycloaddition reactions of alkene radical cations. Anodic oxidation of olefins produces electrophilic alkene radical cations, which further react with nucleophilic diazo compounds in a formal [2+1] cycloaddition towards cyclopropane synthesis. This methodology is also applicable for [2+2] cycloadditions with styrene derivatives, validating this efficient electrochemical system for both cyclopropane and cyclobutane ring synthesis. The advantages of this methods include the mild, metal and catalyst free conditions, simple setup, and scalability of the procedure, as well as its potential use for industrial applications since the method requires non-expensive graphite electrodes.

References:

a) Skubi, K. L., Blum, T. R., Yoon, T. P. Chem.
Rev.
2016, 116, 17, 10035-10074. b) Romero, N. A., Nicewicz, D. A. Chem.
Rev.
2016, 116, 17, 10075-10166 c) Prier, C. K., Rankic, D. A., MacMillan, D. W. C. Chem.
Rev.
2013, 113, 7, 5322-5363. d) Donabauer, K., König, B. Chem. Res.
2021, 54,1, 242-252.

Yan, M., Kawamata, Y., Baran, P. S. Chem Rev.
2017, 117, 21, 13230-13319. b) Zhu, C., Ang, N. W., Meyer, T. A., Qiu, Y., Ackermann, L. ACS Cent. Sci.
2021, 7, 3, 415-431. c) Pollok, D., Waldvogel, S. R. Sci.
2020, 11, 12386-12400. d) Meyer, T. H., Choi, I., Tian, C., Ackermann Chem
2020, 6, 2484-2496. e) Yan, M., Kawamata, Y., Baran, P. S. Angew. Chem. Int. Ed.
2018, 57, 4149-4155.

Tay, N., Lehnherr, D., Rovis, T. Chem.
Rev.
2022, 122, 2, 2487-2649.

a) Kingston, C., Palkowitz, M. D., Takahira, Y., Vantourout, J. C., Peters., B. K., Kawamata, Y., Baran, P. S. Chem. Res.
2020, 53, 1, 72-83. b)Wirtanen, T. Prenzel, J-P. Tessonnier, S. R. Waldvogel Electroorganic Synthesis, Chem. Rev.
2021, 121, 10241–10270. c) Sbei, N., Hardwick, T., Ahmed, N. ACS Sustainable Chem. Eng.
2021, 9, 61-48-6169.

Yuan, Y., Lei, A. Nature Communications.
2020, 802.

Figure 1
Electrochemical Synthesis of Selected λ3- and λ5-Iodanes
Authors: Bystron Tomas , Jirasko Martin , Devadas Balamurugan , Kvicala Jaroslav
Published: September 2023

Numerous λ3- and λ5-iodanes are used as highly selective oxidants in organic synthesis and are considered as a green alternative to classical metal based (CrVI, MnVII, ...) oxidants. The main advantage of iodanes is substantially lower toxicity and environmental footprint. However, their synthesis is based on chemical oxidation of iodobenzenes which usually involves handling toxic or at least potentially unstable oxidants (e.g. bromate, chlorine, persulfate or percarboxylic acids). This represents safety issue which becomes significant especially when scale-up of the process beyond laboratory level is required. Application of electrochemical synthesis of iodanes offers substantial advantage over the classical chemical approach in a sence no chemical oxidants are required. However, up to this point, no cheap, sustainable and easily scalable process for electrochemical synthesis of λ3-iodanes has been published. The main problems is that majority of the authors use environmentally unfriendly solvents and often workup of the product is complicated or even missing. In the case of electrochemical synthesis of λ5-iodanes, the situation is even worse since there is just handfull of publications on the topic.

In the present contribution, a process of electrochemical synthesis of selected λ3- and λ5-iodanes (based on our previous publications [1-3]) including solid product workup, will be presented. In particular, the electrochemical process is based on anodic oxidation of 2-iodobenzoic acid to 2-iodosylbenzoic acid and 2-iodylbenzoic acid (IBX) using boron-doped diamond electrode. This step proceeds with high current efficiency, selectivity and product yield. Separation involves precipitation, crystallisation and filtration. No product washing with organic solvents is required. It is important to note that during the process development the attention was paid to minimisation of the environmental footprint of the process (high atom efficiency, low amount of waste, absence of toxic chemicals), low price of the chemicals and process scalability.

References

[1] T. Bystron, A. Horbenko, K. Syslova, K.K. Hii, K. Hellgardt, G. Kelsall, 2-Iodoxybenzoic Acid Synthesis by Oxidation of 2-Iodobenzoic Acid at a Boron-Doped Diamond Anode, ChemElectroChem, 5 (2018) 1002-1005.

[2] B. Devadas, J. Svoboda, M. Krupička, T. Bystron, Electrochemical and spectroscopic study of 2-iodobenzoic acid and 2-iodosobenzoic acid anodic oxidation in aqueous environment, Electrochimica Acta, 342 (2020) 136080.

[3] T. Bystron, B. Devadas, K. Bouzek, J. Svoboda, V. Kolarikova, J. Kvicala, Anodic Oxidation of Iodobenzene and Iodobenzoic Acids in Acetic Acid Environment – Electrochemical Investigation and Density Functional Theory Study, ChemElectroChem, 8 (2021) 3755-3761.
Anodic Oxidation of Bisamides
Authors: Becker James Y. , Golub Tatiana
Published: September 2023

Previously [1] we studied the anodic oxidation of symmetrical bisamides of type RCONH(CH2)nNHCOR (n = 2-4) under constant current electrolysis (CCE), in methanol. Those with 3 and 4 methylene groups as spacers undergo mostly mono- and dimethoxylation at the alpha-position to 'N' atom. However, when the spacer contains two methylene groups only, the anodic process favors fragmentation products due to CH2-CH2 bond cleavage, as shown in Eq. 1.

Following the above results, for better selectivity, the anodic oxidation of symmetrical aromatic bisamides with ‘CH2CH2’ as a spacer (ArCONHCH2CH2NHCOAr), was investigated [2] in acetonitrile, and under controlled potential electrolysis (CPE). The outcome indicates that the major products involve unsymmetrical geminal bisamides (Eq. 2) that are difficult to synthesize by other methods.

References

[1] T. Golub and J.Y. Becker, Beilstein J. Org. Chem.
2018,
14, 861–868.

[2] T. Golub, G.-Y. Dou, C.-C. Zeng and J. Y. Becker, Org. Lett., 2019, 21, 7961-7964;

J.Y. Becker, unpublished results (2022).

Figure 1
Probing Reactions at the Nanoscale Surface through Nanoelectrochemistry
Authors: Andreescu Emanuela Silvana
Published: September 2023

Nanoparticle collision electrochemistry provides extensive capabilities for the assessment and characterization of the processes occurring at the surface of metal and metal oxide nanoparticles with extremely high sensitivity. Understanding the surface chemistry, interactions and transformation of engineered nanomaterials with environmental constituents is a fundamental need for characterizing their properties and advance applications of these materials for environmental sensing and remediation. This presentation will describe development of a nanoelectrochemical technique for evaluating the surface properties, functionalization and reactivity of metal and metal oxide nanoparticles with environmental contaminants. The presentation will demonstrate the potential of this method for the: 1) assessment of surface reactivity of redox active nanoparticles, 2) monitoring surface adsorption/desorption and speciation of metal ions at oxide nanoparticles with single particle resolution, and 3) as a method for rapid and sensitive detection of perfluoroalkyl and polyfluoroalkyl substances (PFASs) using redox nanoparticle probes. We will also demonstrate capabilities of this method as a novel tool for detecting environmental contaminants through their interaction with nanoparticle probes. Potential advantages and limitations of this approach as a method for the routine study of nanoparticles and their use as probes to evaluate fundamental environmental chemical processes will also be discussed.
Electrochemical Activation of Metabolic Enzymes in Human Liver S9 Fractions
Authors: Walgama Charuksha , Omanakuttan Bhavana
Published: September 2023

Human liver subcellular fractions such as liver microsomes, liver cytosol fractions, or S9 fractions are widely used in in-vitro assays to predict liver metabolism. The S9 fractions are the supernatants of human liver homogenates consist of both human liver microsomes and the cytosol. Therefore, these fractions contain majority of cytochrome P450 (CYP) enzymes and soluble phase II enzymes like glucuronosyltransferases, N-acetyl transferases, sulfotransferases, and glutathione-S-transferases. Here we report the direct electrochemistry and biocatalytic features of redox active enzymes impregnated in S9 fractions. We investigated the electrochemical properties of S9 films by immobilizing them onto a high purity graphite electrode and performing cyclic voltammetry in anaerobic (Ar saturated) and aerobic (O2 saturated) conditions. The electron transfer between the S9 film and the high purity graphite electrode was observed at the formal potential of -0.48 V, with respect to Ag/AgCl reference electrode, which confirmed the activation of CYP450 reductase enzyme in the film. These films also demonstrated a catalytic oxygen reduction with a maximum current density of ~0.5 mA cm-2 at the scan rate of 0.050V/s. We investigated the CYP activity in the S9 biofilm for phase 1 metabolism using diclofenac hydroxylation as a probe reaction and could able to identify metabolic products using liquid chromatography-mass spectrometry (LC-MS) technique. Eventually, we envision to develop a platform to perform both phase I and II metabolic reactions in a single electrochemical assay.
Electroanalytical Meat Science
Authors: Krishnan Sadagopan , Nerimetla Rajasekhara , Kasthuri Dias Sandun Bogahawaththa , Ramanathan Ranjith
Published: September 2023

Meat color is the fundamental property directing consumers’ purchase decisions. The bright red color of the meat is indicative of its freshness. For electrochemists, the redox properties of meat proteins and pigments are favorable target molecules to probe and understand the meat color attributes under various meat-relevant pH, temperature, and aerobic/anaerobic conditions. This presentation discusses our findings on the electroanalysis of meat properties, starting with a simple myoglobin model and extension to meat extracts. Our long-term goal is to devise an electroanalytical tool for meat color and quality assessments offering simplicity, portability, and cost-effectiveness.
(Invited) Use of Redox Mediators and Polymers to Provide Additional Control of Bioelectrocatalytic Systems
Authors: Minteer Shelley D.
Published: September 2023

Mediated electron transfer is a critical strategy for "wiring" biomolecules to electrode interfaces in bioelectrochemical systems. Specifically in enzymatic bioelectrocatalysis, soluble redox mediators and redox polymers have been critical for both improving the catalytic performance, but also improving the selectivity of the bioelectrodes. This paper will discuss the design and implementation of redox mediators and redox polymers in bioelectrocatalytic systems. Application of these concepts to the fields of electrosynthesis, bioanalysis supercapacitors, and redox flow biobatteries will be discussed.