bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited, Digital Presentation) Polybenzimidazole and Its Use in Energy Storage and Conversion
Authors: Henkensmeier Dirk 
Published: July 2022

Polybenzimidazole (PBI) is a unique polymer. It has high mechanical strength and stability, and is not conductive. However, in contact with acids, the imidazole rings are protonated, and PBI becomes proton conductive. In contact with alkaline solutions, the amine groups are deprotonated, and PBI becomes hydroxide conductive. Control of the doping process allows to adjust the uptake and hence allows to control conductivity and permeability of PBI membranes. Therefore, PBI can be used in various ways for several applications.

Phosphoric acid doped PBI blends were tested in the HT PEMFC, and showed more than >2000 hours stable, high performance operation at very challenging high current density of 800 mA/cm2 (one of world-best results).[1]

Sulfuric acid doped PBI membranes were developed for use in the vanadium redox flow battery. We show that stable performances with an energy efficiency >91% and coulomb efficiency >99% @ 80 mA/cm2 can be achieved, which is one of the highest reported performances.[2, 3]

By using a newly developed membrane fabrication process, hydroxide conducting membranes with a conductivity of > 310 mS/cm2 were be obtained. Porous supports enhanced the mechanical stability of these membranes, and PEM-water electrolyser-like performance was achieved in an alkaline water electrolyser, which was successfully operated for 1000 hours without failure.[4]

A common way to increase the mechanical stability of membranes is reinforcement with a porous support. The drawback is that different swelling ratios of matrix and support can form voids, which results in unacceptably high gas crossover in electrolyzers and fuel cells. To tackle this issue, we pore filled an electrospun PBI fiber mat with a bomoalkylated polymer and reacted it with the imidazole groups available on the PBI fiber surface, thus forming a covalently bonded interface. In a final step, the remaining bromoalkyl groups were quaternized. The membrane was tested for 200 hours in an electrolyzer, and showed no signs of degradation. [5]

[1] N. Nambi Krishnan, N.M.H. Duong, A. Konovalova, J.H. Jang, H.S. Park, H.J. Kim, A. Roznowska, A. Michalak, D. Henkensmeier, Polybenzimidazole / tetrazole-modified poly(arylene ether) blend membranes for high temperature proton exchange membrane fuel cells, J. Membr. Sci., 2020, 614, 118494. https://doi.org/10.1016/j.memsci.2020.118494
[2] C. Noh, D. Serhiichuk, M. Najibah, Y. Kwon, D. Henkensmeier, Optimizing the performance of meta-polybenzimidazole membranes in vanadium redox flow batteries by adding an alkaline pre-swelling step, Chem. Eng, J., 405 (2021) 126574. https://doi.org/10.1016/j.cej.2020.126574
[3] unpublished results
[4] under review
[5] Malikah Najibah, E. Tsoy, H. Khalid, Y. Chen, Q. Li, C. Bae, J. Hnát, M. Plevová, K. Bouzek, J.H. Jang, H.S. Park, Dirk Henkensmeier, PBI nanofiber mat-reinforced anion exchange membranes with covalently linked interfaces for use in water electrolysers, J. Membr. Sci., 2021, 640, 119832. https://doi.org/10.1016/j.memsci.2021.119832
Comparison of Different Optimization Methods for the Microstructure of Proton Exchange Membrane Fuel Cells
Authors: Lamb James , Andrei Petru 
Published: July 2022

Proton exchange membrane fuel cells (PEMFCs) have attracted much attention in the research and commercial sectors because they are environmental friendly and have relatively high power density compared to most other energy storage devices based on electrochemical processes. A significant part of the research on PEMFCs is related to decreasing the cost and improving the structure of PEMFCs by optimizing numerically the microstructure of these devices including the non-uniform porosity, carbon, nafion, and catalyst (i.e. platinum) distributions and the geometrical characteristics. The existing optimization techniques can generally be divided into heuristic and non-heuristic techniques. Heuristic techniques usually use stochastic approaches that search the optimization space using trial-and-error methods. Examples of such techniques include the genetic algorithm, particle swarm optimization, differential evolution, simulating annealing, harmony search, memetic algorithms, etc. These techniques can be applied to optimize a small number of design variables and often need to be used with simplified (often purely mathematic and not based on fundamental physics) models, such as compact, reduced-order models, or equivalent circuit models. On the other hand, non-heuristic techniques are deterministic and often require evaluating the gradient of the objective function. In general, these techniques have local convergence and their rate of convergence can be increased, using second-order derivatives such as the Hessian matrix, or taking advantage of the particular functional form of the objective function. Non-heuristic techniques usually require between a few tens of iterations to optimize the objective function compared to heuristic techniques which require at least tens of thousands of iterations.
In this presentation we will make a thorough critical review of the different optimization methods used in the literature for PEMFCs. In additional, we will present the results of our efforts to develop a full-cell optimization algorithm for PEMFCs using the adjoint method [1-3]. The advantages and disadvantages of different methods, including the adjoint method, will be discussed in detail and examples of sample simulations results will be presented.

References

1. Lamb and P. Andrei, “Optimization of 2-D Spatial Distributions of Pore Sizes, Platinum Content, and Nafion Amount in PEMFC”, ECS Meeting Abstracts, (2021).

Lamb and P. Andrei, ECS Transactions, 98, 67 (2020).

Lamb, G. Mixon and P. Andrei, J. Electrochem. Soc, 164, E3232 (2017).
The Economics of High Temperature and Supercritical Water Electrolysis
Authors: Borsboom-Hanson Tory , Holm Thomas , Merida Walter 
Published: July 2022

The growth of green energy in recent decades has resulted in increasing demand for hydrogen production with net-zero carbon emissions. Water electrolysis provides a solution to meet this demand, however it is currently too expensive to be cost competitive with hydrogen production methods of higher carbon intensity. High-temperatures and pressures can be leveraged to increase the energy efficiency of water electrolysis through kinetics and thermodynamic benefits, thereby reducing the overall cost of green hydrogen [1]. Additionally, performing water electrolysis directly at high pressures can help to avoid the added cost associated with gaseous hydrogen compression.
Little is known about the electrolysis of supercritical water and what benefits it might offer in terms of hydrogen cost reduction [2,3]. In this work, experimental data was collected for supercritical water electrolysis and used to build an electrochemical model suitable for use under those conditions. The results of this model, combined with components of a previously published technoeconomic model for a high-temperature and pressure water electrolysis plant [4], indicate that while supercritical water electrolysis is achievable it is not the most economically efficient choice for hydrogen production. High-temperature and pressure water electrolysis performed under optimal conditions can be used to achieve higher economic efficiency when compared with contemporary water electrolysis solutions. Finally, a thorough optimization of the model presents a grim picture for achieving the US Department of Energy’s $2 kgH2
-1 target through water electrolysis without government subsidy.

References:

[1] D. Todd, M. Schwager, W. Mérida, Thermodynamics of high-temperature, high-pressure water electrolysis, J. Power Sources. 269 (2014) 424–429. https://doi.org/10.1016/j.jpowsour.2014.06.144.
[2] H. Boll, E.. Franck, H. Weingärtner, Electrolysis of supercritical aqueous solutions at temperatures up to 800K and pressures up to 400MPa, J. Chem. Thermodyn. 35 (2003) 625–637. https://doi.org/10.1016/S0021-9614(02)00236-7.
[3] P.C. Ho, D.A. Palmer, Determination of ion association in dilute aqueous potassium chloride and potassium hydroxide solutions to 600°C and 300 MPa by electrical conductance measurements, J. Chem. Eng. Data. 43 (1998) 162–170. https://doi.org/10.1021/je970198b.
[4] T. Holm, T. Borsboom-Hanson, O.E. Herrera, W. Mérida, Hydrogen costs from water electrolysis at high temperature and pressure, Energy Convers. Manag. 237 (2021) 114106. https://doi.org/10.1016/j.enconman.2021.114106.

Figure 1
In-Situ Neutron Imaging and Pore Network Modeling of Counter Current Mass Transfer inside Porous Transport Layers Used for PEMWE
Authors: Altaf Haashir , Vidakovic-Koch Tanja , Tsotsas Evangelos , Vorhauer-Huget Nicole 
Published: July 2022

The specific morphology of porous materials, as well as their physical properties, crucially affect their applications, e.g. their use in fuel cells, batteries, or electrolysers. A key point is the correlation of their transport properties with the spatially distributed pore structure. In polymer electrolyte membrane water electrolysers (PEMWE), the drainage of oxygen, counter-currently to the water supply inside the porous anode, can significantly control the performance of the system. More precisely, the temporal and spatially distributed oxygen coverage of the catalyst layer obstructs the water supply towards it, which can result in a decrease of reaction rate. At the same time affects the heterogeneous distribution of liquid water the temperature distribution inside porous electrodes. This can have a severe impact on the performance of the PEMWE as well as on the degradation of the catalyst material.
In the presented study, mathematical pore network modeling (PNM) was used to investigate the correlation of the porous transport layer (PTL) pore structure with the distribution of water (wetting) and oxygen (non-wetting). The pore network was reconstructed based on the information about porosity, pore size distribution, pore connectivity and pore shape, which were obtained from micro-computed tomography of commercial materials (Fig. 1a). Compared to existing macroscopic models, PNM is suitable for low capillary numbers, takes local wetting characteristics into account and resolves the invasion process at the pore scale. The quasi-static nature of the model provides an edge over other modelling techniques in terms of computational power and additionally the ease of implementation of locally distributed properties. With the help of PNM, it was studied how a change of structure, i.e. the spatial grading of the pore size distribution and porosity, affects the local oxygen and water distribution, as well as the transport properties. This phenomenon was also analyzed experimentally by the use of a non-electrochemical aluminum cell (Fig. 1b and 1c) which was employed in an in-situ imaging setup installed at ILL, Grenoble, France. The recorded water saturations can be compared to the simulation results with the purpose of model validation and further model development. The outcomes of this study can be useful for the development of structural grading strategies with the target of improved transport properties for the efficient removal of the reactant oxygen and the homogeneous distribution of water.

Figure 1
A Spectroscopic Investigation of Photochemical Nitrogen Fixation
Authors: Hatzell Marta , Liu Yu-Hsuan 
Published: July 2022

Photochemical nitrogen transformations were initially pioneered by a prominent Indian soil scientist, N.R. Dhar, in the 1930-40s[1]. Others continued to evaluate this process in the presence of liquid water, water vapor, and oxygen. These results remained unverified until 1977, when Schrauzer and Guth also began to investigate this process on natural minerals[2]. Since the 1970s photochemical nitrogen fixation has been widely studied on a number of photocatalyst[3]. Most conclude that nitrogen is reduce to ammonia through a direct electron-transfer based process. However, the reaction mechanism has not been clearly mapped using spectroscopic techniques. Here, we examine the reaction pathway for nitrogen fixation to ammonia on titania based photocatalyst using multiple spectroscopic techniques. We also aim to focus our talk on explaining the role hole scavengers play in enabling this reaction.
[1]Dhar, N. R., and N. N. Pant. "Nitrogen loss from soils and oxide surfaces." Nature 153.3873 (1944): 115-116.
[2] GN Schrauzer and TD Guth. Photocatalytic reactions. 1. Photolysis of water and photoreduction of nitrogen on titanium dioxide. Journal of the American Chemical Society, 99(22):7189–7193,1977.
[3]Medford, Andrew J., and Marta C. Hatzell. "Photon-driven nitrogen fixation: current progress, thermodynamic considerations, and future outlook." Acs Catalysis 7.4 (2017): 2624-2643.
Exploring the Synergistic Relationship between Organic Synthesis and Electrochemistry
Authors: Moeller Kevin D , Feng Enqi , Ji Chang , Jing Qiwei , Medcalf Zachary 
Published: July 2022

From a personal perspective, it is a joy to watch the larger organic synthesis community embrace and impressively develop new electrochemical methods. Those efforts are teaching us a great deal about not only electrochemical methods, but also how to best take advantage of the opportunities those methods offer. In our group, we continue to contribute to this larger enterprise by examining the role of direct electrochemical oxidation in the exploration of new oxidative cyclization strategies and the radical cation intermediates that are central to their success. These efforts have recently led to new umpolung reactions involving imine groups that are both setting the stage for introducing new levels of selectivity into the formation of non-natural amino acid building blocks and triggering new cascade types of reactions.
Interestingly, the relationship between organic synthesis and electrochemistry can also be viewed in the opposite direction with the new synthetic chemistry being developed in order to facilitate exciting opportunities to expand the scope of electrochemical experiments. For example, new synthetic methods that allow for the site-selective generation of chemical reagents have enabled the construction of complex molecular surfaces on addressable microelectrode arrays. The efforts set the stage for using the microelectrode arrays as analytical devices for rapidly screening the binding behavior of small molecule libraries with biological targets. The method offers a previously unknown level of quality control over the molecular library, and it enables the binding events to be monitored in "real-time" as they happen. However, more complex reactions leading to more complex addressable surfaces also requires better methods for characterizing what has been made and analyzing the biological interactions that arise.
Not surprisingly, the exploration of these new electrochemical tools is beginning to “give back” to the synthetic arena, and a number of preparative scale synthetic applications have now arisen based on the concept of site-selective reagent generation. For example, we have recently discovered that the strategy developed for confinement of a chemical reagent to a specific site on a microelectrode array can also be used to introduce new selectivity into solution phase chemical reactions. In the talk to be given, the interplay between organic synthesis and electrochemistry will be highlighted with an emphasis on how that interplay enables the development of new solutions to challenging synthetic problems.

References:
For reviews see Moeller, K. D. Chem. Rev.
2018, 118, 4817-4833, Jing, Q; Moeller, K. D. Accounts of Chem. Res.
2020,
53, 135-143, and Krueger, R.; Moeller, K. D. J. Org. Chem.
2021, 86, 15487-15865.
Electrochemical Reactivity of N-Alkoxyphthalimides, Towards O Radicals Electrogeneration and Use in Electrosynthesis
Authors: Chicas-Banos Diego Francisco , Gonzalez Bravo Felipe , Miranda Luis Demetrio , Sartillo-Piscil Fernando , Frontana-Uribe Bernardo Antonio 
Published: July 2022

N-alkoxyphthalimides (NAPIs) are compounds known for the capability of oxygen-centered radical generation in the presence of tin reagents and radical initiators,[1] which have led to some inovative synthesis strategies.[2,3] Their reported electrochemical behavior is quite different: carbonylic compounds are obtained through cathodic reduction benzylic NAPIs.[4] Encouraged by an exciting "oxidation under cathodic conditions," we focus our studies on contrasting experimental with simulated cyclic voltammetry data using specialized software aiming to prove a plausible mechanism. The synthetic application to accessing carbonylic compounds through NAPIs electrochemical reduction has been assessed, evaluating different solvents, supporting electrolytes and current densities, and the tolerance of other reactive moieties to the reaction conditions.
[1] Kim, S.; Lee, T. A.; Song, Y. Facile Generation of Alkoxy Radicals from N-Alkoxyphthalimides. Synlett
1998, No. 5, 471–472.
[2] Cortezano-Arellano, O.; Quintero, L.; Sartillo-Piscil, F. Total Synthesis of Cephalosporolide E via a Tandem Radical/Polar Crossover Reaction. The Use of the Radical Cations under Nonoxidative Conditions in Total Synthesis. J. Org. Chem.
2015, 80 (5), 2601–2608.
[3] Zhu, H.; Leung, J. C. T.; Sammis, G. M. Strategies to Control Alkoxy Radical-Initiated Relay Cyclizations for the Synthesis of Oxygenated Tetrahydrofuran Motifs. J. Org. Chem.
2015, 80 (2), 965–979.
[4] Syroeshkin, M. A.; Krylov, I. B.; Hughes, A. M.; Alabugin, I. V.; Nasybullina, D. V.; Sharipov, M. Y.; Gultyai, V. P.; Terent’ev, A. O. Electrochemical Behavior of N-Oxyphthalimides: Cascades Initiating Self-Sustaining Catalytic Reductive N―O Bond Cleavage. J. Phys. Org. Chem.
2017, 30 (9), 1–15.

Figure 1
Electrochemistry of Hypervalent Bromine(III) Compounds
Authors: Francke Robert , Mohebbati Nayereh , Sokolovs Igors , Suna Edgars 
Published: July 2022

The chemistry of hypervalent halogen species has experienced remarkable advancement in the recent decades [1]. However, in comparison to the well-explored hypervalent iodine(III) compounds, little research has been done on the isoelectronic bromine(III) counterparts [2]. This is mainly due to the difficult-to-control reactivity of λ
3-bromanes as well as to the challenges associated with the conventional protocol for their preparation from the highly toxic and corrosive precursor BrF3 [3]. In this context, we present a straightforward and scalable approach to λ
3-bromanes by anodic oxidation of parent aryl bromides. A series of para-substituted λ
3-bromanes with remarkably high redox potentials spanning a range from 1.86 V to 2.60 V vs. Ag/AgNO3 was synthesized by the electrochemical method. We demonstrate that the bench-stable bromine(III) species can be activated by addition of a Lewis or a Brønsted acid and used for various synthetic applications [4].
The developed electrochemical approach to λ
3-bromanes offers considerable advantages compared to previously established methods since stoichiometric reagents are replaced by electric current and the use of hazardous precursors is omitted. Therefore, our approach may open the door to the development of unprecedented synthetic transformations that would benefit from the unique properties of hypervalent bromine(III) species. Mechanistic studies on formation and activation of the bromanes are underway [5].

References:

1. Yoshimura, A.; Zhdankin, V. V., Chem Rev
2016,
116, 3328-435.
2. Miyamoto, K., Chemistry of Hypervalent Bromine. In PATAI'S Chemistry of Functional Groups
2018, pp 1-25.
3. Farooq, U.; Shah, A. A.; Wirth, T., Angew. Chem. Int. Ed.
2009, 48, 1018-1020.
4. Sokolovs, I.; Mohebbati, N.; Francke, R.; Suna, E., Angew. Chem. Int. Ed.
2021,
60, 15832-15837.
5. Mohebbati, N.; Sokolovs, I.; Woitke, P.; Leito, I.; Roemelt, M.; Suna, E.; Francke, R.; 2022, manuscript in preparation.

Figure 1
Interpretations of Electrochemical Impedance Drift at Different Surfaces
Authors: Halpern Jeffrey M , Ziino Emily , Panahi Zahra , Marnoto Sabrina , Austin Katherine , Feeney Stanley 
Published: July 2022

Electrochemical impedance spectroscopy (EIS) is used to evaluate the resistive state of an electrode surface. EIS is growing more popular in evaluating materials for biosensors and energy applications. In the case of biosensors, EIS can passively evaluate the binding event of a biomolecule to a surface recognition element. We have studied EIS inconsistent measurements from a bare carbon electrode under various conditions to evaluate the associated drift over multiple runs.[1] Without changing any variables run-to-run, a measurable drift can be expressed linearly or as a Langmuir isotherm over multiple measurements. The total change in charge transfer resistance is dependent on the solution and media, including the choice of surfactant used to solubilize various analytes.
Herein we will report our progress of EIS measurements from multiple different surfaces including peptides, polymers, and bare electrodes. We found that drift can be associated with specific surface changes (decoupling of surface modification or changes in surface states) and adsorbing of solution media to the surface. In the case of the bare electrode, surfactant and solution choice is important to minimize drift and increase confidence in run-to-run measurements.
Acknowledgements: The authors would like to acknowledge the financial support from NIH (P20 GM113131).
References:
[1] E. Ziino, S. Marnoto, J.M. Halpern, Investigation to Minimize Electrochemical Impedance Spectroscopy Drift, ECS Trans. 97 (2020) 737–745. https://doi.org/10.1149/09707.0737ecst.
(Digital Presentation) TiO2 Photoelectrochemical Radical-Cation Vinylcyclopropane Rearrangements
Authors: Okada Yohei , Maeta Naoya , Kamiya Hihidero 
Published: July 2022

In the field of synthetic organic chemistry, photochemical and electrochemical methods are often considered to be competing techniques that induce single electron transfer (SET). Recently, metal complexes and organic dyes have been extensively used as molecular sensitizers that can induce homogeneous bidirectional SET. On the other hand, heterogeneous monodirectional SET can be induced by electrodes, which differs from the photochemical methods. In this context, semiconductors are unique alternatives, since they can induce heterogeneous but bidirectional SET, potentially enjoying advantages of both photochemical and electrochemical methods. Such semiconductor "photoelectrochemical" methods may trigger the reactions that are otherwise difficult to achieve.
We have been developing electrochemical SET-triggered cycloadditions in lithium perchlorate (LiClO4)/nitromethane (CH3NO2) solution, which facilitates the generation of radical cations from electron-rich alkenes and styrenes. Recently, we also have been focusing on TiO2 photoelectrochemical SET-triggered cycloadditions, expanding a scope of the electrochemical versions. During the course of our study to develop new TiO2 photoelectrochemical SET-triggered cycloadditions, we unexpectedly found that vinylcyclopropane rearrangements was also possible in LiClO4/CH3NO2 solution. The reactions are initiated by oxidative SET by hole, which is followed by immediate ringopening of the cyclopropanes to generate distonic radical cations. It is expected that reductive SET by excited electron is also involved to realize effective net redox-neutral transformations. Experimental details, including preliminary mechanistic studies, will be presented in this talk.
References:
1. Chem. Rec.
2021, 21, 2223–2238.
2. Chem. Rev.
2018, 118, 4592–4630.
3. J. Org. Chem.
2020, 85, 6551–6566.