bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supramolecular Interactions between Reduced Vitamin K1 and Dissolved CO2 and H2o in Aprotic Solvents
Authors: Webster Richard David 
Published: February 2024

Vitamin K1 is a naphthoquinone (NQ) that can be electrochemically reduced at negative potentials in two one-electron steps in aprotic organic solvents. The first electron transfer at potential E
1 forms the anion radical (NQ•
–) and the second electron transfer process at potential E
2 results in the formation of the dianion (NQ2–). If a hydrogen bond donor (H-D) such as water or an alcohol is progressively added to the aprotic organic solvent, both E
1 and E
2 shift towards more positive potentials. The shifts in potential are much greater for E
2 compared to E
1 as the hydrogen bond donor is added, so that a sufficiently high donor concentration, E
2 merges with E
1 and only one voltammetric wave is observed at potential E
3 due to the transfer of two-electrons. The shifts in potential with added hydrogen bond donors can be rationalized by supramolecular interactions between the strongly electronegative oxygen atoms in the quinone anions (especially the dianions) and the donor hydrogen atoms, and can be modelled according to an electrochemical square-scheme mechanism involving multiple electron transfer and chemical bonding steps.
NQ + e– ⇌ NQ•
–
E
1

NQ•
– + e– ⇌ NQ2–
E
2

NQ + 2e– + nH-D ⇌ [NQ(H-D)n]2–
E
3

NQ + 2e– + nCO2 ⇌ [NQ(CO2)n]2–
E
4

In addition to H-bonding interactions, reduced forms of NQ also undergo supramolecular interactions with CO2(g) when it is purged into solution. Similar to the situation seen for H-bonding, when CO2 is purged into solution, the two one-electron processes merge into one two-electron process at less negative potentials (E
4). The mechanism can be considered analogous to the H-bonding case where the electronegative oxygen atoms in the reduced quinones interact with the electropositive carbon atoms in CO2. However, the supramolecular interactions appear to be stronger with CO2 than with water, since substantially less CO2 needs to be added to cause the two one-electron reduction processes of NQ to merge into one two-electron process. Controlled potential electrolysis experiments were conducted to determine the chemical reversibility of the supramolecular interactions. It was found that, (i) fully reducing NQ under a CO2 atmosphere and then applying an oxidizing potential resulted in the 100% conversion back to the starting material and, (ii) reducing NQ under a CO2 atmosphere and then purging the solution with argon resulted in the CO2 being released as CO2(g) or CO2
•
– to leave NQ in its neutral form or as NQ2–.

Figure 1.
Cyclic voltammograms for 1,4-naphthoquinone in acetonitrile containing 0.2 M Bu4NPF6 at a scan rate of 0.1 V s–1 at a 1 mm diameter planar Pt electrode in the presence and absence of CO2.

Figure 1
(Keynote) Are Organic and Biological Electrochemistry That Different?
Authors: Schröder Uwe 
Published: February 2024

In the context of green chemistry, electrochemical processes are playing an increasingly important role. This currently leads – alongside developments in the battery sector – to an impressive revival of electrochemistry. For the conversion of regenerative feedstocks, both classical organic and biological electrochemistry play a central role. Interestingly, the developments in both sectors are running separately - also in separate communities.
In this presentation, the potentials of bioelectrochemical and classical electroorganic reactions will be compared and their strengths as well as limitations highlighted. Furthermore, potential synergies will also be identified and aspects of sustainable reaction design will be discussed.
Combining Electrochemistry and Protein Engineering to Elucidate Outer-Sphere Effects in Hydrogenase Catalysis
Authors: Leger Christophe 
Published: February 2024

Hydrogenases, the bacterial enzymes that oxidize and produce H2, come in two flavors, “NiFe hydrogenases” and “FeFe hydrogenases”, depending on the structure of their active site.
In each of these two families of enzymes, the active site and its immediate environment are fully conserved, and yet the investigations of these enzymes using direct electrochemistry have shown that their catalytic properties vary greatly: this is true regarding catalytic bias and reversibility1, resistance to oxygen, and other properties which define whether or not a particular hydrogenase could be used under the operating conditions of a particular device.
These functional variations within each family also tell us that structural features that are remote from the active site, the so-called “outer-sphere” effects, define, at least in part, the catalytic properties.2

In the FeFe hydrogenase from Clostridium beijerinckii, we have shown that oxygen resistance is related to a conformational change that depends on non-conserved residues that are up to 18 Å away from the active site. This conformational change occurs in two steps that can be resolved by combining site-directed mutagenesis and detailed protein film voltammetry experiments.3

These remote residues define an emerging family of O2-resistant FeFe hydrogenases.

(a) A. Fasano, H. Land, V. Fourmond, G. Berggren, and C. Léger, « Reversible or irreversible catalysis of H+/H2 conversion by FeFe hydrogenases », J. Am. Chem. Soc. 143, 48, 20320-20325 (2021) (b) V. Fourmond, N. Plumeré, C. Léger, « Reversible catalysis », Nature Reviews Chemistry, 5, 348-360 (2021)

S. Stripp, B. Duffus, V. Fourmond, C. Léger, S. Leimkühler, S. Hirota, Y. Hu, A. Jasniewski, H. Ogata, M. Ribbe, « Second and Outer Coordination Sphere Effects in Low Valent Metalloenzymes », Chemical Reviews, 122 11900 (2022)

(a) M. Winkler, J. Duan, A. Rutz, C. Felbek, L. Scholtysek, O. Lampret, J. Jaenecke, U.-P.r Apfel, G. Gilardi, F. Valetti, V. Fourmond, E. Hofmann, C. Léger, T. Happe « A safety cap protects hydrogenase from oxygen attack » Nature Communications 12, 756 (2021) (b) A. Rutz, C. Das, A. Fasano, J. Jaenecke, S. Yadav, U.P. Apfel, V. Engelbrecht, V. Fourmond, C. Léger, L. Schäfer, T. Happe « Increasing the O2 resistance of the [FeFe]-hydrogenase CbA5H through enhanced protein flexibility », ACS Catalysis 13, 2, 856–865 (2023)

Figure 1
Direct Electrochemical Reductive Synthesis - a Tool for Novel Classes of N-Oxy Heterocycles
Authors: Winter Johannes , Waldvogel Siegfried R 
Published: February 2024

Nitrogen containing heterocycles represent an important and common structural motif in natural products and blockbuster pharmaceuticals. Thus, their synthesis plays a crucial role in the chemical industry. The N-oxy motif is commonly found as major metabolites for such nitrogen containing heterocycles. As an innovative tool, electrochemistry enables direct access to N-oxy heterocycles via direct reduction of easily accessible nitro arenes. By using electrical current from renewable resources as an inherently safe and inexpensive reagent, electrochemistry contributes to an increased sustainability of chemical processes.[1,2]

A simple galvanostatic set-up in an undivided beaker-type cell with inexpensive electrolytes was used to access a broad variety of quinoline N-oxides and 1-oxy quinazolin-4-ones in up to a multi-gram scale. This toolset offers an innovative synthetic protocol for synthesizing this novel class of compounds by only using sustainable chemicals and electricity as an inherently safe reagent.[3,4]

References:
[1] D. Pollok, S. R. Waldvogel, Chem. Sci.
2020, 11, 12375–12592.
[2] T. Wirtanen, E. Rodrigo, S. R. Waldvogel, Adv.Synth.Catal.
2020, 362, 2088–2101.
[3] J. Winter, T. Prenzel, T. Wirtanen, D. Schollmeyer, S. R. Waldvogel, Chem.–Eur. J.
2022, 29, e202203319.
[4] O. Koleda, T. Prenzel, J. Winter, T. Hirohata, M. d. J. Gálvez-Vázquez, D. Schollmeyer, S. Inagi, E. Suna, S. R. Waldvogel, Chem. Sci.
2023, 14, 2669–2675.
Is Ethanol Essential for the Lithium-Mediated Nitrogen Reduction Reaction?
Authors: Mygind Jon Bjarke Valbaek , Bruun Pedersen Jakob , Vesborg Peter , Li Katja , Deissler Niklas Henrik , Saccoccio Mattia , Li Shaofeng , Kibsgaard Jakob , Fu Xianbiao , Andersen Suzanne Zamany , Chorkendorff Ib , Sazinas Rokas 
Published: February 2024

Ammonia is used extensively as a fertilizer in agriculture and in the chemical industry. It also has the potential to store carbon-neutral fuel (hydrogen) in the future. To help meet the future demand for ammonia, the electrochemical nitrogen reduction reaction (NRR) has received much attention. It would serve as a decentralized method of synthesizing ammonia at low temperature and pressure. [1]
To this day, the most promising NRR results have been shown via the lithium-mediated approach, in which lithium metal is electroplated in an organic electrolyte containing a lithium salt, saturated nitrogen gas, and a proton shuttle. The saturated nitrogen in the electrolyte reacts with electrodeposited lithium and protons are subsequently delivered by the shuttle. The local availabilities of protons and nitrogen are crucial for achieving a high selectivity towards ammonia rather than hydrogen evolution. The selectivity is heavily affected by the solid electrolyte interphase (SEI) which is formed between the electrodeposited lithium and bulk electrolyte. [2,3,4,5]
This study investigates the role of ethanol as the proton shuttle in the lithium-mediated nitrogen reduction reaction (Li-NRR). In situ mass spectrometry and electrochemical quartz crystal microbalance are used to elucidate the importance of ethanol. Furthermore, particularly designed chronopotentiometry experiments are designed to provide additional information, allowing for a detailed discussion of ethanol’s multifaceted role in the Li-NRR. It is shown that ethanol is crucial for the formation of the SEI, but not necessary for the actual synthesis of ammonia. The SEI formation in the Li-NRR system is critically influenced by ethanol at the onset of lithium plating. Ethanol is not necessary to shuttle protons from the anode to the cathode. Furthermore, it is shown that lithium is an active species in the Li-NRR system even without electrochemistry. Finally, it is revealed that ethanol plays an important role in the context of anodic electrode potentials and electrolyte stability.
References

MacFarlane, D. R. et al. Adv. Mater. 32, 1904804 (2020)

Du, H-L et al. Nature 609, 722 (2022)

Lazaouski, N. et al. ACS Catal. 12, 5197-5208 (2022)

Andersen, S. Z. et al. Energy Environ. Sci. 13, 4291-4300 (2020)

Andersen, S. Z. et al. Nature 570, 504 (2019)
The Impact of Concentration and Electric-Field Dependent Susceptibilities on Electrolyte Models
Authors: Landstorfer Manuel 
Published: February 2024

Electrolytes have a significant role in a range of scientific and technological fields such as fundamental electrochemistry, biochemical systems, semiconductors, and industrial devices. A widely used mathematical framework for describing electrolytes is based on Poisson-Nernst-Planck-type equations and their successors[1], but the Poisson equation assumes a constant dielectric susceptibility. However, recent research has developed a thermodynamically consistent model for the dielectric susceptibility that accounts for its dependence on both concentration and electric field [5,6]. This allows for the inclusion of the dependency of the susceptibility on salt concentration in liquid electrolytes, referred to as dielectric decrement[2,3,4], as well as the decline in susceptibility for large electric fields[8], known as dielectric saturation.
The research findings highlight the importance of considering the variable dielectric susceptibility in electrolyte models, particularly in relation to the decrease in dielectric permittivity in front of a charged electrode surface[7]. The study demonstrates the impact of the concentration and electric-field-dependent susceptibility on the overall equation system for electrochemical double layers. By providing insights into the theoretical aspects of the approach, the researchers aim to contribute to the development of more accurate and comprehensive models of electrolytes that consider the complex interplay of various factors.

References

[1] W. Dreyer, C. Guhlke, and R. Müller. Phys. Chem. Chem. Phys.(2013), 15:7075–7086.
[2] R. Buchner, G. T. Hefter, and P. M. May. Dielectric relaxation of aqueous NaCl solutions. The Journal of Physical Chemistry A (1999), 103(1):1–9.
[3] J. B. Hasted, D. M. Ritson, and C. H. Collie. Dielectric properties of aqueous ionic solutions. parts I and II. J. Chem. Phys. (1948), 16(1):1–21.
[4] Y. Marcus. Evaluation of the static permittivity of aqueous electrolytes. J. Solution Chem.(2013), 42(12):2354–2363,.
[5] M. Landstorfer, C. Guhlke, W. Dreyer, Electrochimica Acta (2016), 201, 187-219.
[6] M. Landstorfer, R. Müller, Electrochimica Acta (2022), 428, 140368.
[7] O. Teschke, G. Ceotto, and E. F. de Souza. Phys. Rev. E(2001), 64:011605,.
[8] D. C. Grahame. The Journal of Chemical Physics(1950), 18(7):903–909.
Electrode Reactions on Conducting Polymers
Authors: Vagin Mikhail Yu. 
Published: February 2024

The electrocatalysis behind the direct chemical-to-electrical energy interconversion is one of key facets in the development of sustainable economy. This results in a technological demand for a variety of applications such as electrical transportation, electrified synthesis and the grid balancing. Here are three examples of problematized electrocatalytic processes. (A) The sluggish kinetics and multistep character of oxygen reduction reaction (ORR) are causing losses in electrical energy conversion and poor selectivity, which limit the wide implementation of oxygen-associated energy conversion technologies. (B) The water electrolysis yielding the hydrogen evolution reaction (HER), the key process in technologies of green hydrogen, provides only 4% of worldwide hydrogen production due to the high catalyst cost. (C) The control of the proton-coupled electron transfers on organic redox molecules such as benzenediols. These three illustrate the stimulus of the intensive research on noble-metal-free electrocatalysts. Conducting polymers, the organic materials synthesised from abundant element, constitute a distinct class of molecular electrocatalysts [1, 2] attributed with behaviour of mixed ion-electron conductors (MIEC). Firstly, the landscape of ORR phenomena happening on p- and n-type conducting polymers at the mechanistic and device levels are discussed [1-3]. Secondly, the effect of proton supply is rationalized at both mechanistic and device levels for HER on PEDOT-triflate [4]. Thirdly, the significant effect of ionic transport on the rate of the proton-coupled electron transfers was observed and conceptualized as a ion-selective electrocatalysis (ISEC) [5].
[1] E. Mitraka, M. Gryszel, M. Vagin, M.J. Jafar, A. Singh, M. Warczak, M. Mitrakas, M. Berggren, T. Ederth, I. Zozoulenko, X. Crispin, E.D. Głowacki, Electrocatalytic Production of Hydrogen Peroxide with Poly(3,4‐ethylenedioxythiophene) Electrodes, Advanced Sustainable Systems, 3 (2019) 1800110.
[2] Z.X. Wu, P.H. Ding, V. Gueskine, R. Boyd, E.D. Glowacki, M. Oden, X. Crispin, M. Berggren, E.M. Bjork, M. Vagin, Conducting Polymer-Based e-Refinery for Sustainable Hydrogen Peroxide Production, Energy & Environmental Materials.
[3] M. Vagin, V. Gueskine, E. Mitraka, S.H. Wang, A. Singh, I. Zozoulenko, M. Berggren, S. Fabiano, X. Crispin, Negatively-Doped Conducting Polymers for Oxygen Reduction Reaction, Advanced Energy Materials, 11 (2021) 2002664.
[4] R. Valiollahi, M. Vagin, V. Gueskine, A. Singh, S.A. Grigoriev, A.S. Pushkarev, I.V. Pushkareva, M. Fahlman, X.J. Liu, Z. Khan, M. Berggren, I. Zozoulenko, X. Crispin, Electrochemical hydrogen production on a metal-free polymer, Sustainable Energy & Fuels, 3 (2019) 3387-3398.
[5] M. Vagin, C.Y. Che, V. Gueskine, M. Berggren, X. Crispin, Ion-Selective Electrocatalysis on Conducting Polymer Electrodes - Improving the Performance of Redox Flow Batteries, Advanced Functional Materials, 30 (2020) 2007009.
Heterogeneous Capture and Release of Energy Metals Using Carborane-Tethered Electrodes
Authors: Menard Gabriel , Mattejat Maxwell , Benhaim Hila 
Published: February 2024

Li and U are the only trace metals dissolved in seawater that are proposed to be economical to extract. Both are at very low concentrations (Li (0.17 ppm), U (3.3 ppb)); however, their total content are approximately 10,000 and 1,000 times higher than in land-based reserves, respectively, representing huge untapped resources which could be collected in an environmentally friendly manner. With surging demand for Li-ion batteries for energy storage, it is estimated that current production methods will soon not meet market demands. In addition, low-carbon nuclear energy production is also expected to increase dramatically in many major countries.
Previous studies have shown that reduction of the substituted closo-carborane polyhedral cluster, 1,2-L2-C2B10H10, to the nido-carborane, [1,2-L2-C2B10H10]2-, resulted in the rupture of the C–C bond, cage opening, and an increased bite angle, Θ (Scheme). This talk will start by describing how we used this redox-controlled chelation for the selective electrochemical capture and release of UO2
2+ from mixed-metal mixtures mimicking spent nuclear fuel in monophasic and biphasic media (Scheme; M = UO2
2+; L = Ph2PO).1-2 We will then discuss our current efforts to target other metals of energy importance, in particular M = Li+, for seawater extraction by incorporating Li-selective donating groups, L (Scheme). This talk will then focus heavily on our current work on anchoring these carboranes onto electrode surfaces using anchoring groups – e.g., allyl, pyrene, or thiols – for heterogeneous capture and release using galvanostatic charge/discharge cycles. Recent, soon-to-be published results demonstrate the successful application of this redox-controlled chelation for heterogeneous, selective capture of UO2
2+ from mixed-metal mixtures.

Keener, M.; Hunt, C.; Carroll, T. G.; Kampel, V.; Dobrovetsky, R.; Hayton, T. W.; Ménard, G. Redox-switchable carboranes for uranium capture and release. Nature
2020,
577, 652-655.

Keener, M.; Mattejat, M.; Zheng, S.-L.; Wu, G.; Hayton, T. W.; Ménard, G. Selective electrochemical capture and release of uranyl from aqueous alkali, lanthanide, and actinide mixtures using redox-switchable carboranes. Chem. Sci.
2022,
13, 3369-3374.

Figure 1
Electrochemical Stimulation of Monopolar Electrodes
Authors: Scherson Daniel , Heer Arvind Singh , Mantelli Harlan , Georgescu Nicholas , Han Qi 
Published: February 2024

Changes in the electrostatic potential within an aqueous acidic solution induced by the passage of current between the Au disk of a stationary Au|Au ring disk electrode and a distant counter electrode, Idisk made it possible to stimulate the reduction of selenite to elemental selenium at the concentric Au ring electrode polarized at Eringo just positive to its otherwise expected onset. This effect was ascribed to variations in the surface overpotential, and, thus, in the rates of selenite reduction along the ring, we define, hereafter, as a monopolar electrode. The stimulation efficiency could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ring linearly toward positive potentials to yield selenite. Shown in the figure below is a series of linear scan \voltammograms, LSV, recorded at a scan rate of 50 mV/s for the ring polarized at Eringo in the range 0.39 - 0.45 V (see legend) following Nstim = 40 between Edisk = 0.75 and 1.00 V, where the black curve corresponds to the LSV recorded without any prior stimulation under otherwise identical conditions. As clearly indicated the stripping charge associated with the oxidation of elemental Se increases as the potential at which the ring is polarized is decreased. Excellent quantitative agreement was obtained between the current flowing through the ring, Iring , and Eringo as a fucntion of Idisk and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This novel tactic is expected to open new prospects for gaining insight into surface
diffusion and other interfacial dynamics phenomena.
Acknowledgements
This work was supported by the US NSF Award 1808592
Literature Cited
1) Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Electrochim. Acta 2019, 325, 134957

Figure 1
Elucidating Oxygen Reduction Mechanisms on Organic Mixed Ionic-Electronic Conducting Polymers
Authors: De La Fuente Duran Ana , Liang Allen Yu-Lun , Denti Ilaria , Penn Emily E , Marks Adam , Chueh William C. , Salleo Alberto , Giovannitti Alexander , Mefford J. Tyler 
Published: February 2024

Atmospheric oxygen is an attractive oxidant for the generation of electricity from chemical fuels and for the electrochemical production of hydrogen peroxide. Although not universal, it is generally assumed that an electrocatalyst is needed to reduce oxygen. Recently, a variety of organic mixed ionic-electronic conducting polymers (OMIECs) have been reported to exhibit catalytic behavior for both the 4-electron/4-proton and the 2-electron/2-proton oxygen reduction reaction (ORR).
This work sets out to identify the oxygen reduction mechanism of OMIECs through a multi-faceted experimental and theoretical approach. We primarily focus our efforts on p(NDI-T2 P75)—a random copolymer comprised of naphthalene diimide (NDI) and bithiophene (T2) units with 75% polar sidechains—and then expand the understanding built on this system to a range of other OMIECs. Using rotating ring disk electrochemistry, we find that the investigated OMIECs exhibit a high selectivity towards the 2-electron ORR product. Using operando UV-Vis and Raman spectroscopy measurements, we identify changes in OMIEC performance when in the presence of O2. To gain further insights about the catalytic reaction path, we construct and test a microkinetic model. Through this model, we show that the performance of the tested OMIECs can be rationalized through an EC’D reaction mechanism. Our results suggest that these materials do not operate as electrocatalysts for the initial reduction of oxygen to superoxide but do function as catalysts for the disproportionation of superoxide.
Electrochemical Phosphorous Recovery from Wastewater: Modeling & Scale-up Considerations
Authors: Wolfe Kody D , Zanganeh Ardavan , Arthur Richard N , Trembly Jason , Daramola Damilola 
Published: February 2024

The prospect of electrifying the recovery of valuable nutrients from waste streams is of great interest in the effort of reducing the overall energy consumption and environmental impact of nutrient usage. Currently, many electrochemical precipitation technologies exist, and some have shown energy consumption values on par with implemented nutrient recovery technologies (both gravimetric for specified products and volumetric for waste stream handling). However, electrochemical precipitation technologies are at low-to-intermediate Technology Readiness Levels (TRLs) and need to be optimized and scaled to determine the feasibility of implementing them industrially. This presentation discusses necessary considerations for modeling and scaling electrochemical precipitation technologies from the perspective of phosphorus (P) recovery.
Two specific modeling tools were used to study P recovery as struvite. Mass transport and electrochemical phenomenon were modeled using COMSOL within a stirred batch reactor format. The COMSOL modelling yields valuable information about limiting conditions, spatial distribution of dissolved species concentrations, and the effects of various reactor conditions (e.g., stirring or applied potential). Next, the precipitation of struvite under various solution conditions is discussed with respect to a thermodynamic model of precipitation developed using OLI Flowsheets. The precipitation study is then discussed with respect to modeled reactor conditions to ascertain information relevant to scaling electrochemical P precipitation. Figures of Merit (FOM) useful in scaling electrochemical reactions are highlighted to alleviate the dependence on the reactor design used for modelling, enabling a transfer of information to other reactor formats.