bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilising Fourier Transform Voltammetry to Advance the Enzyme Electrochemistry Toolkit
Authors: Lloyd-Laney Henry , Yates Nicholas , Stapleton James , Hewson Alice , Baranska Natalia , Bond Alan , Gavaghan David , Parkin Alison
Published: February 2024

Electron transfer and redox chemistry drives life and Biology can provide inspiration for the design of sustainable fuel catalysts that achieve highly active and selective small molecule transformations. In particular, the Parkin group are interested in hydrogenases,1 biological H2-producing enzymes, and lytic polysaccharide monooxygenases (LPMOs),2, 3 enzymes that breakdown cellulose. We seek to understand how the rate and energetics of electron transfer controls catalysis in such enzymes;4 to do this we collaborate with the Gavaghan and Bond groups to develop more powerful bioelectrochemical methodologies.5 This talk will describe our most recent efforts to integrate sinusoidal voltammetry into our enzyme-electrochemistry toolkit.6, 7 The technique offers advantages in terms of simulation speed, which in turn enables the powerful application of Bayesian statistical analysis to visualise the uncertainty in the modelling approach. However, we still rely on large amplitude Fourier transform voltammetry and direct current methodologies to visualise the Faradaic current and readily define redox reaction parameter bounds.

References:

[1] H. Adamson, M. Robinson, J. J. Wright, L. A. Flanagan, J. Walton, D. Elton, D. J. Gavaghan, A. M. Bond, M. M. Roessler and A. Parkin, J. Am. Chem. Soc., 2017, 139, 10677-10686.

[2] P. J. Lindley, A. Parkin, G. J. Davies and P. H. Walton, Faraday Discuss., 2022, 234, 336-348.

[3] J. Branch, B. S. Rajagopal, A. Paradisi, N. Yates, P. J. Lindley, J. Smith, K. Hollingsworth, W. B. Turnbull, B. Henrissat, A. Parkin, A. Berry and G. R. Hemsworth, Biochem. J., 2021, 478, 2927-2944.

[4] A. R. Dale-Evans, M. J. Robinson, H. O. Lloyd-Laney, D. J. Gavaghan, A. M. Bond and A. Parkin, Front. Chemistry, 2021, 9.

[5] H. Adamson, A. M. Bond and A. Parkin, Chem. Comm., 2017, 53, 9519-9533.

[6] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. D. Firth, D. M. Elton, J. Zhang, A. M. Bond, A. Parkin and D. J. Gavaghan, Anal. Chem., 2021, 93, 2062-2071.

[7] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. Branch, G. R. Hemsworth, A. M. Bond, A. Parkin and D. J. Gavaghan, Journal of Electroanalytical Chemistry, 2023, 935, 117264.
Direct Electrochemical Regeneration of NADH and Its Biomimetics
Authors: Hickey David P. , Bruggeman Chase
Published: February 2024

Enzyme-catalyzed redox transformations are an attractive approach for conversion of unactivated alkanes into value-added products under mild reaction conditions. This is especially true since advancements in the area of enzyme engineering has led to a dramatic expansion in the use of modified oxidoreductases for selective functionalization of commodity petrochemicals in non-aqueous media. Despite their appeal, many redox enzymes rely on stoichiometric quantities of expensive coenzymes, such as nicotinamide adenine dinucleotide (NADH), that are not easily regenerated. The use of direct electrochemistry to catalytically regenerate NADH has long been an aspiration of chemists as a convenient and straightforward method that would enable use of the expensive cofactor in enzyme-catalyzed synthesis on an industrial scale. Unfortunately, direct electrochemical reduction of the oxidized form of nicotinamide adenine dinucleotide (NAD+) results in unstable radical intermediates that rapidly form biologically inactive byproducts. Recent progress has been made towards the development of inexpensive artificial NADH biomimetics as replacements for the natural coenzyme, but the strategies to regenerate these biomimetic coenzymes is equally limiting. A primary focus of our research is to design synthetic analogues of NAD+ and NADH that are both enzymatically active and electrochemically regenerable. We will present our recent progress in understanding the structure-reactivity relationships that lead to dimerization over the preferred formation of 1,4-dihydronicotinamide in NAD+ and its biomimetics, and we will describe strategies to prevent dimerization of electrochemically reduced NAD+.
(Keynote) Reversible CO2 Reduction Electrocatalysis in Solar-Powered Chemistry
Authors: Reisner Erwin
Published: February 2024

Semi-artificial photosynthesis interfaces biological catalysts with synthetic materials such as electrodes or light absorbers to overcome limitations in natural and artificial photosynthesis. The benefit of using biocatalysts in electrocatalytic CO2 reduction is their electrochemical reversibility that enables their operation at very low overpotentials with high selectivity. This presentation will summarise my research group’s progress in integrating the CO2 reducing enzyme formate dehydrogenase into bespoke hierarchical 3D electrode scaffolds and the exploitation in solar-powered catalysis. I will present the electrochemical features and characterisation of the biocatalyst-material interface and provide my team's understanding of the electrochemical properties of the immobilised formate dehydrogenase. This insight allows the wiring of the biocatalyst into electrocatalytic schemes, photoelectrochemical devices and photocatalytic systems for unique CO2 utilisation reactions. The fundamental insights gained by integrating isolated formate dehydrogenase in electrodes will be presented and the case be made that this enzyme allows opening a solar-to-chemical conversion space that is currently not accessible with purly synthetic or biological catalysts (see uploaded Image as example).

Recent publications: (1) Lam et al., Angew. Chem. Int. Ed., 2023, in print. (2) Bhattacharjee et al., Nat. Synth., 2023, 2, 182-92. (3) Badiani et al., J. Am. Chem. Soc., 2022, 144, 14207-16. (4) Cobb et al., Nat. Chem., 2022, 14, 417-24. (5) Edwardes Moore et al., Proc. Natl. Acad. Sci. USA, 2022, 119, e2114097199. (6) Anton Garcia et al., Nat. Synth. 2022, 1, 77-86.

Reviews: (1) Fang et al., Chem. Soc. Rev., 2020, 49, 4926–52. (2) Zhang & Reisner, Nature Rev. Chem., 2020, 4, 6–21. (3) Kornienko et al., Acc. Chem. Res., 2019, 52, 1439–44. (4) Kornienko et al., Nature Nanotech., 2018, 13, 890–99
Anodic Synthesis of Peptides in Biphasic Electrolytic Solutions
Authors: Chiba Kazuhiro , Shinjo Shingo , Kitano Yoshikazu , Okada Yohei
Published: February 2024

Peptide synthesis requires a large amount of condensing reagents, and once the condensation is complete, all of the reagents become waste. Based on the recognition of these issues, we decided to investigate the possibility of linking the condensing agent function to electrode electron transfer. Using this reaction system, all the elongation reaction steps were carried out by the electrolytic method. The electrolytic peptide synthesis method has been confirmed to efficiently proceed with the condensation of all amino acids, and the products and by-products can be easily separated. It is expected to be applied as a material production method that significantly reduces the use of energy and materials.
Formation of Arylsulfinates Using Electroreductive Cleavage of Cone-Calix[4]Arene Nosylates – EPR and Theoretical Study
Authors: Liška Alan , Klíma Jiří , Ludvík Jiří
Published: February 2024

Nosylates are used as protecting groups. In a non-redox hydrolytic process, the leaving group is the corresponding sulfonate anion. Upon electrochemical reduction of nosylates (here six cone-calix[4]arene-bis-nosylates; i.e. 4-nitrophenylsulfonate aryl esters) using mercury electrodes (DC-polarography and cyclic voltammetry - CV) combined with in-situ EPR-spectroelectrochemistry in aprotic DMF, the mechanism is different. All studied calix[4]arene-bis-nosylates are reduced in a first reversible step to bis-nitroradical anion) which was proved by EPR. The stability of the multiple radical ions proves the absence of electron communication among the redox centers on the calixarene macrocycle which was observed previously in other systems1-3.

In the second reduction step next 2×2 electrons are transferred and both sulfonate ester groups are cleaved to two 4-nitro-benzenesulfinate ions and a calixarene bis-phenolate (95%) under splitting of the S-O bond.4 The mechanism of electroreductive generation of arylsulfinate anions is a significant finding from electrosynthetic point of view. Synthesis of activated arylsulfinates is generally difficult for their low stability. Nevertheless, they can be easily prepared by electrochemical reduction of calixarene nosyl esters.

Acknowledgement

This work was supported by the grant GAČR 21-23261S (Czech Science Foundation) with the institutional support RVO: 61388955. The authors are grateful to colleagues ing. Markéta Řezanková, prof. Jan Budka and prof. Pavel Lhoták (University of Chemistry and Technology, Prague) for synthesis and granting the substances.

References:

[1] Liška, A., Vojtíšek, P., Fry, A. J., Ludvík, J. (2013) The Journal of Org. Chem., 78(21), 10651-10656.

[2] Liška, A., Rosenkranz, M., Klíma, J., Dunsch, L., Lhoták, P., Ludvík, J. (2014) Electrochimica Acta, 140, 572-578.

[3] Liška, A., Vojtíšek, P., Ludvík, J. (2019) Chemical Communications, 55(19), 2817-2820.

[4] Liška, A., Řezanková, M., Klíma, J., Urban, J., Budka, J., Ludvík, J. Electrochem. Sci. Advances, DOI:10.1002/elsa.202100221.
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.
Iron-Mediated Electrolysis for Selective Oxidative Decarboxylation of C-Terminal Acids Using Metal-Binding Residue
Authors: Sowers Adam J. , Halskov Kim S. , Moeller Kevin D
Published: February 2024

With the increasing concern of the environmental impact of solid-phase peptide synthesis (SPPS), semi-recombinant processes, in which recombinantly expressed peptides are selectively modified, are of growing interest. The strategies employed for these modifications must overcome the challenges associated with recombinant peptides: selectivity across many functional groups and solubility of the full-length peptide. Electrochemistry is a viable solution to these challenges as it is a mild and tunable process which can operate in both organic and aqueous systems. Herein, a model tetramer with a redox-active residue, tyrosine, is selectively decarboxylated at the C-terminus in an iron-mediated electrolysis. Chemoselectivity is achieved by exploiting the metal-binding property of a C-terminal glutamic acid residue. In the presence of the iron mediator, the tyrosine oxidation pathway is suppressed while the oxidative decarboxylation pathway is favored. Mechanistic controls demonstrate that the glutamic acid, iron, and applied current are all necessary to impart the desired chemoselectivity.
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)
Monitoring the State of Health (SOH) of Green Batteries (GreenBat)
Authors: Sandrucci Eugenio , Marini Federico , Brutti Sergio
Published: February 2024

Here we focus on the study of state of health monitoring of secondary batteries with advanced “green” formulations. European recycle map on battery energy storage plans to replace positive electrodes consisting of cobalt (Co) and fluorinated (F) graphite-based negative electrodes constituents with environmentally sustainable alternatives. Recently, "green formulations" was validated; in particular, recent trends suggest the use of electrodes based on silicon (Si), Co-free manganites (LiMnO2) aqueous soluble binders and fluorine-free electrolytes [1]. Our aims are to describe the health and the degradation of the cells with electrochemical techniques and to describe the chemical and morphological changes occurring during the battery cycling, through spectroscopies (Raman and IR) operating in parallel with impedance analysis. These experimental data will be integrated together in a multiblock dataset, which will constitute the basis for chemometric processing. The purpose of this chemometric modelling is to correlate SOH evolution to the chemical and physical state of the battery [1]. Here we illustrate the analysis of SOH of two different pouch cells formulation constituted by LTO (Lithium-Titanate) as anode, LFP (Lithium-Iron-Phosphate) as cathode and the LP30 electrolyte (EC:DMC 1:1 and LiPF6 1M); the second formulation is constituted by a thin film layer of commercial Li metal (purity of 99.7%) as anode, LFP as cathode and an ethers based formulation as electrolyte. After formation cycles (CC-CV), the cells have been submitted to aging tests. The different operating conditions are chosen with an Experimental Design (ED) and supported by a PCA analysis. The PCA analysis it was used to choose the operating parameters for the subsequent aging experiments. Is illustrated also the analysis of SOH of a coin cell formulation consisted by a LRLO (Lithium Rich Layer Oxide) as anode, commercial Li metal layer as cathode and LP30 additive with a ionic liquid (IL) as electrolyte. Turning to the chemometric modelling, as a starting point we verified the ability of PLS regression applied to the voltage profiles during charge cycles to estimate the SOH of a benchmark dataset by Lin et al. [1]

References

[1] M. Lin,D. Wu, Journal of Power Sources, 2022, 518, 230774.

Figure 1
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.
High-Efficiency Cycling Piezo-Degradation of Organic Pollutants and the Piezocatalysis–Adsorption Duality of MoS2 Nanoflowers
Authors: Lin Hsun-Yen
Published: February 2024

This study realized the large-scale piezo-catalytic RhB dye degradation by forming a catalytic filter of 2H phase MoS2 and carbon cloth. Over 2.5 liters of the organic pollutant can be fully decomposed through the application of a water pumping system. The results obtained indicate that 2H MoS2 NFs were highly reusable and have excellent potential for the application in industrial wastewater treatment. Furthermore, this study theoretically and experimentally investigates the piezocatalytic and adsorption effects of different phases of polymorphic MoS2 NFs. By adjusting the electrostatic surface charge of these NFs and the RhB solution, different crystalline phases of MoS2 NFs would result in either adsorption or piezo-catalytic effects toward the organic dye. The results evident that the cationic dye is adsorbed on the surfaces of the 1T MoS2 NFs; however, the few-layer 2H MoS2 NFs generate a considerable quantity of hydroxyl species for degrading RhB molecules through the mechanical-force-induced piezo-potential.

Figure 1
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.
Electrochemical Oxidation of Synthetic Wastewater Sludge on Ni Foam for Nutrient Recovery
Authors: Barrera Luisa , Sahin Elif Selin , Botte Gerardine G , Hatzell Marta
Published: February 2024

Continued growth of the world’s population as well as shifting socio-economic trends have been tied to increasing demands for food and water. Due to upcoming worldwide environmental crises, there needs to be a shift towards a circular economy, where key nutrients are not lost but repurposed. For example, high-yield food crops depend on the application of nitrogen and phosphorus-based fertilizers, which are respectively made using highly energy intensive methods, like the Haber-Bosch process, and non-renewable limited resources, such as phosphate rock. In addition, water that has been contaminated by human activity is being treated in a multitude of manners, with the overarching drawbacks being high energy consumption and, in some cases, the production of a secondary waste stream. In particular, wastewater sludge is a nutrient-rich waste stream with high levels of nitrogen and phosphorus stored in organic bonds that is most commonly sent to landfills for disposal.

In this talk, we focus on the electrochemical oxidation of wastewater sludge for the recovery of ammonia and other nutrients. We used a synthetic wastewater sludge composition to better understand the contributions of each component on the formed end-products. We probed the potential dependence of these end-products by conducting fixed-potential tests in a H-cell with Ni foam electrodes. This work contributes to the ongoing efforts in the Center of Advancing Sustainable and Distributed Fertilizer Production (CASFER).
Considerations of Reference Electrodes and Liquid Junction Potentials for Accurate Electrocatalysis Studies
Authors: Kawashima Kenta , Marquez-Montes Raul A. , Son Yoon Jun , Milton Antony Elvin Fernando , Le Thuy Vy , Guo Clarissa , Smith Lettie A. , Chukwuneke Chikaodili E. , Vaidyula Rinish Reddy , Mullins Charles Buddie
Published: February 2024

For lab-scale electrocatalysis studies, one typically uses a three-electrode system, which consists of working, counter (auxiliary), and reference electrodes, an electrolyte solution, and a reactor. In this system, it is important for accurate electrochemical studies to select an appropriate reference electrode for a particular electrolyte solution and recognize the presence/absence of liquid junction potential at the frit of a reference electrode. For instance, in alkaline water electrocatalysis experiments, Hg/HgO, Ag/AgCl, or saturated calomel electrode (SCE) is generally used as a reference electrode, and 1 M KOH/NaOH aqueous solution is utilized as an electrolyte solution.1 In this regard, the Ag/AgCl electrode and SCE are unsuitable for electrochemical studies with alkaline electrolytes, and among them, only the Hg/HgO electrode can be used instead.1 Furthermore, if the internal solution of a reference electrode and the external electrolyte solution are different in constituent and/or concentration, the liquid junction potential will be established at the frit of a reference electrode. In this case, to accurately know the potential applied to a working electrode, this liquid junction potential as well as the iR drop caused by solution resistance need to be considered and corrected appropriately. However, the liquid junction potential has so far been ignored in most of the electrocatalysis studies.

In this work, we will discuss a method to experimentally estimate the liquid junction potential at the reference electrode frit using three-electrode systems with different combinations of electrolytes and reference electrodes. Herein, we will deal with alkaline water electrolysis systems as representatives. The as-estimated values of various liquid junction potentials will be compared with the theoretical values obtained using the Henderson equation2 and the stationary Nernst–Planck equation.3 Additionally, the guideline for selecting an appropriate reference electrode depending on the types of external electrolyte solutions will be discussed briefly. We believe that these findings can improve the accuracy of reporting potential-related parameters (e.g., overpotential, half-wave potential, onset potential, etc.) in three-electrode system-based electrocatalysis studies.

References

K. Kawashima et al., ACS Catal., 13, 1893–1898 (2023).

R. G. Bates, Determination of pH, 2nd ed., p. 36–44, A Wiley-Interscience Publication, New York, New York, (1973).

M. Marino, L. Misuri, and D. Brogioli, (2014) https://arxiv.org/abs/1403.3640v2.
Gas-Phase CuPd Bimetallic Cluster-Modified Electrodes as Model Electrocatalysts for CO2 Conversion
Authors: Papamichail Dimitra , Balalta Deema , Abbas Imran , Song Jason , Altantzis Thomas , Bals Sara , Pant Deepak , Janssens Ewald , Grandjean Didier , Lievens Peter
Published: February 2024

Copper-based electrocatalysts possess the unique ability to convert CO2 to multicarbon products such as ethylene – a precursor in many industrial processes. However, their stability and product selectivity remain insufficient. A promising approach to overcome these shortcomings and design better CO2RR electrocatalysts is to tune Cu selectivity by forming bimetallic Cu-M systems [1] while establishing their detailed structure-selectivity relationship. To achieve this, we used laser ablation Cluster Beam Deposition (CBD) [2] to produce well-defined bimetallic cluster-modified electrodes [2]. More specifically, CuPd clusters with an original average size of 2.5 nm and mass loadings of 1-3 µg cm-2 were deposited onto a carbon support. To produce a model catalyst which allows the independent investigation of the electronic and geometric structural effects induced to Cu by the second element, a Cu0.9Pd0.1 composition was selected [3]. CuPd cluster-decorated electrodes were tested for CO2 electrolysis and methane (C1), and ethylene (C2) were found among the products. Observed from the electrocatalytic activity trends, the evolution of C2 products is correlated with the cluster mass loading. In addition, the cluster coverage has an effect on the onset of the competitive H2 evolution (HER); with the lowest cluster-loaded electrodes presenting more intense HER due to limited cluster coverage of the carbon substrate. High resolution (Scanning) Transmission Electron Microscopy ((S)TEM) coupled with Energy-dispersive X-ray spectroscopy (EDX), and X-ray Photoelectron Spectroscopy (XPS) analyses of the as-prepared cluster-modified electrodes, show that the clusters feature some degree of CuPd alloying in the ambient. CuPd cluster-based systems will then be investigated in-situ using X-ray absorption spectroscopy to unravel their structure-catalytic performance relationship.

References:

[1] X. Zhang et al., Materials Today Advances, 7, 2020

[2] V. C. Chinnabathini, et al., Nanoscale, 2023, DOI: 10.1039/D2NR07287D

[3] L. Zaza et al., ACS Energy Letters, 7, 4, 1284–1291, 2022
Temperature-Dependent Investigation of ORR Kinetics on Non-Precious Metal-Free Catalysts in Alkaline Media - Doping Effect on Electrocatalysis
Authors: Das Rubul , Neergat Manoj
Published: February 2024

The kinetic analysis of oxygen reduction reaction (ORR) on non-precious catalysts is cumbersome due to the formation of more than one major products ( and ). In the present study, ORR is investigated on Vulcan XC-72 (C) and a metal-free nitrogen-doped (~≤ 1%) carbon (N/C-900) catalysts in 0.1 M KOH [1]. The experiments are conducted in the temperature range of 293–323 K using a rotating ring disk electrode (RRDE) assembly to quantify the product distribution, viz., and . The measured kinetic current () is partitioned into and on the basis of the potential-dependent product distribution ( and ) .and is used in the estimation of kinetic parameters [2]. The α values are derived from Butler-Volmer (B-V) theory, Tafel equation at high overpotentials (η), and from the derivative of the change in Gibbs free energy of activation () with respect to η. The α values obtained from all the three methods are different. Therefore, the origin of the difference in the α values is the subject of the present investigation. The seemingly unreasonable values of (> 1.0)on N/C-900 may be due to the alternative lower energy path for the formation of activated complex along with the change in the free energy of the reactant [3,4]. On C, it does not provide any alternative pathway for the formation of activated complex and perhaps η influences only the energy state of the reactant. Therefore, the free energy of activation for the formation of activated complex is a stronger function of η on N/C-900 and an indication of strong electrocatalysis.

References

B. Bera, T. Kar, A. Chakraborty, M. Neergat, J. Electroanal. Chem., 805, 184–192 (2017).

R. Das, D. Choudhury, R. Maurya, S. Sharma, M. Neergat, Langmuir,39 (12), 4351–4361 (2023).

U. Stimming, J. Wang, A. Bund, ChemPhysChem, 20 (22), 3004–3009 (2019).

R. Maurya, R. Das, A. K. Tripathi, M. Neergat, Phys. Chem. Chem. Phys., 25, 700–707 (2023).

*Corresponding author:

Tel.: +91 22 2576 7893; Fax: +91 22 2576 4890

E-mail: nmanoj@iitb.ac.in (M. Neergat)