bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Breaking the Bottlenecks in Electrochemical Nitrogen Reduction
Authors: Stephens Ifan 
Published: August 2024

There is a burgeoning interest in the development of a green method of ammonia synthesis; ammonia, already critical for fertilisers in the agricultural industry, is also being touted as a possible future energy vector or carbon-free fuel. The current method of production - the Haber Bosch process - is environmentally damaging and energy intensive but to date no viable alternative has been demonstrated. An electrochemical method operating under ambient conditions would be particularly attractive, as it would enable ammonia to be produced on a decentralised basis on-site and on-demand.1

Thus far, amongst solid electrodes, only lithium and calcium based electrodes in organic electrolytes can unequivocally reduce nitrogen to ammonia.2-4 Even so, at present, there is ample room for improvement.
To investigate this reaction, we use a combination of electrochemical experiments, cryo-microscopy, infrared spectroscopy, electrochemistry mass spectrometry, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy and density functional theory. By drawing from the adjacent fields of enzymatic nitrogen reduction and battery science, we will aim to build a holistic picture of the factors controlling nitrogen reduction.
I will explore the role of the individual electrolyte components, including the cation, the salt, solvent and proton carrier.5-
7 On the basis of the insight, I will propose avenues towards higher rates and higher efficiencies in electrochemical nitrogen reduction.
1 Westhead, O., Barrio, J., Bagger, A., Murray, J. W., Rossmeisl, J., Titirici, M.-M., Jervis, R., Fantuzzi, A., Ashley, A. & Stephens, I. E. L.
Nature Reviews Chemistry
7, 184, (2023).
2 Andersen, S. Z., Colic, V., Yang, S., Schwalbe, J. A., Nielander, A. C., McEnaney, J. M., Enemark-Rasmussen, K., Baker, J. G., Singh, A. R., Rohr, B. A., Statt, M. J., Blair, S. J., Mezzavilla, S., Kibsgaard, J., Vesborg, P. C. K., Cargnello, M., Bent, S. F., Jaramillo, T. F., Stephens, I. E. L., Norskov, J. K. & Chorkendorff, I.
Nature
570, 504, (2019).
3 Westhead, O., Jervis, R. & Stephens, I. E. L.
Science
372, 1149, (2021).
4 Fu, X., Niemann, V. A., Zhou, Y., Li, S., Zhang, K., Pedersen, J. B., Saccoccio, M., Andersen, S. Z., Enemark-Rasmussen, K., Benedek, P., Xu, A., Deissler, N. H., Mygind, J. B. V., Nielander, A. C., Kibsgaard, J., Vesborg, P. C. K., Nørskov, J. K., Jaramillo, T. F. & Chorkendorff, I.
Nature Materials
, (2023).
5 Bagger, A., Wan, H., Stephens, I. E. L. & Rossmeisl, J.
ACS Catalysis
11, 6596, (2021).
6 Spry, M., Westhead, O., Tort, R., Moss, B., Katayama, Y., Titirici, M.-M., Stephens, I. E. L. & Bagger, A.
ACS Energy Letters
, 1230, (2023).
7 Westhead, O., Spry, M., Bagger, A., Shen, Z., Yadegari, H., Favero, S., Tort, R., Titirici, M., Ryan, M. P., Jervis, R., Katayama, Y., Aguadero, A., Regoutz, A., Grimaud, A. & Stephens, I. E. L.
Journal of Materials Chemistry A
, (2023).
Tetrazole-Containing Polyelectrolytes: A New Class of Ion-Solvating Membranes for Alkaline Water Electrolysis
Authors: Serhiichuk Dmytro , Rajappan Sinu Charamchirail , Krishnan Yogeshwaran , Xia Yifan , Kraglund Mikkel Rykær , Hansen Heine Anton , Jensen Jens Oluf Oluf , Aili David 
Published: August 2024

Alkaline ion-solvating membranes, such as those based on polybenzimidazole (PBI), offer high ion conductivity and good gas barrier properties, making them promising for next-generation alkaline water electrolyzers.1 However, the stability of commonly used PBI derivatives is limited due to gradual backbone degradation. Consequently, alternative PBI chemistries and other polymer options like poly(vinyl alcohol),2 and carboxylate functionalized styrene-ethylene-butylene copolymers are being explored to address this inherent stability issue.3

In this study, we present the synthesis and characterization of a novel type of ion-solvating membranes for alkaline water electrolyzers. These membranes are based on tetrazole functionalized polymers derived from poly(styrene-co-acrylonitrile). A one-step click-type [3+2] cycloaddition reaction was utilized to introduce tetrazole pendants by converting acrylonitrile groups in poly(styrene-co-acrylonitrile). The degree of functionalization was controlled by adjusting the content of acrylonitrile units in the polymer. Subsequent treatment in aqueous KOH solution led to the formation of negatively charged tetrazolide pendants with high ionization degrees.
The alkaline stability of the tetrazolides was evaluated using both DFT simulations and model compound studies, demonstrating remarkable stability with no degradation observed for over 3000 hours in 25 wt.% KOH at 80 °C. Physicochemical properties such as electrolyte uptake, swelling behavior, thermal stability, and ion conductivity were assessed for the synthesized polymers. The electrolyte-imbibed membranes exhibited high ion conductivity, reaching up to 90 mS cm-1 in 15 wt% KOH at 80 °C. Electrolysis operation using these membranes showed stable performance for 600 hours with no signs of degradation.

1 D. Aili, M. R. Kraglund, S. C. Rajappan, D. Serhiichuk, Y. Xia, V. Deimede, J. Kallitsis, C. Bae, P. Jannasch, D. Henkensmeier, J. O. Jensen, ACS Energy Letters, 2023, 1900–1910.

2 Y. Xia, S. C. Rajappan, D. Serhiichuk, M. R. Kraglund, J. O. Jensen, D. Aili, J Memb Sci 2023, 680, 121719.

3 D. Serhiichuk, D. Tian, M. R. Almind, Z. Ma, Y. Xia, M. R. Kraglund, C. Bae, J. O. Jensen, D. Aili ACS Applied Energy Materials 2024 7 (3), 1080-1091

Figure 1 Tetrazolation of poly(styrene-co-acrylonitrile) and formation of corresponding potassium tetrazolide following equilibration in aqueous KOH.

Figure 1
AEM Water Electrolysis with Ni-Based Catalysts and Tailored Poly(arylene piperidinium) Materials for Improved Stability
Authors: Hagner Luis , Metzler Lukas , Koch Susanne , Klingenhof Malte , Strasser Peter , Weber Richard , Landrock Michelle , Sommer Michael , Vierrath Severin 
Published: August 2024

Anion-exchange membrane water electrolysis (AEMWE) is a promising low-temperature technology for hydrogen production. It leverages the advantages of the currently dominant technologies (alkaline water electrolysis and proton-exchange membrane water electrolysis) by using transition metal group based catalysts and a zero-gap configuration, enabling high efficiency. However, current AEMWE systems show a limited stability and efficiency.
In this work, commercial and non-commercial polymers are used to fabricate catalyst-coated membranes with a production method oriented towards scalable production (1). A tailored poly(arylene piperidinium) polymer (PAP) shows enhanced stability compared to commercial Aemion+TM during 100 h operation at 1 A/cm2 and 60 °C in 1 M KOH electrolyte (Figure 1) (2). Additionally, different anode catalysts are employed and measured in a reference electrode setup to separate the cell voltage into contributions from the anode and cathode (3). Here, the overpotential of Ni(OH)2 is higher compared to the more active NiFe-layered-double-hydroxide(LDH) and iridium oxide. Employing this setup to measure individual degradation of cathode and anode is part of ongoing research.
Figure 1. a) Tailored PAP material compared to Aemion+TM based systems operated at 1 A/cm2 showing a linear degradation of ca. 400 µV/h. b) Polarization curves of AEMWE single cells with different anode catalysts, measured with an integrated reference electrode setup, which allows to distinguish anode and cathode contribution to the cell voltage. Measured at 60 °C in 1 M KOH electrolyte, 5 cm2 cell area.
References

Koch, S.; Metzler, L.; Kilian, S. K.; Heizmann, P. A.; Lombeck, F.; Breitwieser, M.; Vierrath, S. Toward Scalable Production: Catalyst‐Coated Membranes (CCMs) for Anion‐Exchange Membrane Water Electrolysis via Direct Bar Coating. Advanced Sustainable Systems
2023,
7 (2). DOI: 10.1002/adsu.202200332.

Weber, R.; Klingenhof, M.; Koch, S.; Metzler, L.; Merzdorf, T.; Meier-Haack, J.; Strasser, P.; Vierrath, S.; Sommer, M. Meta -kinks are key to binder performance of poly(arylene piperidinium) ionomers for alkaline membrane water electrolysis using non-noble metal catalysts. J. Mater. Chem. A [Online]
2024,
12 (13), 7826–7836.

Xu, Q.; Oener, S. Z.; Lindquist, G.; Jiang, H.; Li, C.; Boettcher, S. W. Integrated Reference Electrodes in Anion-Exchange-Membrane Electrolyzers: Impact of Stainless-Steel Gas-Diffusion Layers and Internal Mechanical Pressure. ACS Energy Lett. [Online]
2021,
6 (2), 305–312.

Figure 1
Analysis and Improvement of Characterisation Methods for Transport Properties of Gas Diffusion Layers (GDL) for Pemfcs
Authors: Uhlemayr Theresa , Messerschmidt Matthias 
Published: August 2024

Target of the presented work is to determine absolute values of GDL parameters with high accuracy, analysing and avoiding error sources caused by both test equipment and measurement methodology to the highest possible extent. The focus is on electrical, thermal and gas transport. Error sources are examined and identified. Specific attention is paid to identify inherent, inevitable measurement uncertainties. As an example, stacking of GDLs as a method to separate the contact and bulk through-plane electrical resistance of the material under compression will be reviewed in detail. In addition, the influence of the sample dimension, the sample orientation and the sample preparation is shown in examples.
The results presented are acquired within the project QM-GDL (GDL quality assurance for the market run-up), which is funded by the German Federal Ministry for Digital and Transport under grant agreement number 03B11016C.
Electrocatalytic Radical Cation Diels-Alder Reactions Using Enol Ethers As Dienophiles
Authors: Morizumi Haruka , Nakayama Kaii , Kitano Yoshikazu , Okada Yohei 
Published: August 2024

Single-electron oxidation enables the conversion of electron-rich alkenes such as styrene derivatives to radical cation species. We have been developing various cycloaddition reactions of radical cations produced by single-electron oxidation using electrochemical and TiO2 photochemical methods. Introducing an electron-rich aryl group which we call a redox tag is a critical part of the process to control the reactivity of the radical cations. During carbon-carbon bonds formation the motif functions as both electron donor and electron acceptor. In addition to styrene derivatives, enol ethers can also be readily oxidized by single electron transfer (SET) electrochemically or photochemically to generate the radical cations. For instance, enol ethers tethered redox tag serves efficient radical cation precursors for [2+2] cycloadditions.[1] The cycloadditions are net redox-neutral reactions and are initiated by the formation of a radical cation by single-electron oxidation and completed by reduction after ring formation.
Herein, we present [4+2] cycloadditions using enol ethers as dienophiles by electrochemical oxidation in lithium perchlorate (LiClO4)/nitromethane (MeNO2) system. In the case of disubstituted enol ethers prepared from aldehydes, the approach involving redox tag was successful in obtaining the corresponding cycloadducts, while the desired products were not obtained when the substrates without redox tag were subjected.[2] This result suggests that intramolecular electron transfer from the redox tag is crucial for the formation of the cyclohexene ring systems. In contrast, the trisubstituted enol ethers prepared from ketones allowed the cycloaddition reaction to proceed without the involvement of redox tag. It is expected that the methyl group significantly stabilizes the cyclohexene radical cations to have enough lifetime to be reduced by intermolecular SET. Furthermore, since the cycloaddition reaction of enol ether was completed with a catalytic amount of electricity (0.4 F/mol), a radical cation chain mechanism is proposed in which electron acts as a catalyst.

References

[1] Okada, Y.; Maeta, N.; Nakayama, K.; Kamiya, H. J. Org. Chem.
2018, 83, 4948−4962.
[2] Synlett
2023, accepted.

Figure 1
A Comprehensive Online Analytical System Coupled with Standardized Data Analysis for the Electrochemical Reduction of CO2
Authors: Senocrate Alessandro , Kraus Peter , Bernasconi Francesco , Battaglia Corsin 
Published: August 2024

The electrochemical reduction of CO2 (CO2RR) is a promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and thus to achieve a circular carbon economy.
1 Depending on catalyst type and reaction conditions, different gaseous and liquid products can be obtained from the CO2RR, and their production rates vary with reaction time. It becomes thus imperative, for any catalytic performance analysis, to be able to assess the product distribution online during CO2RR.
2,3 However, while gaseous products are readily analyzed online by gas chromatography, liquid products are typically only assessed at the end of the reaction due to the lack of suitable automated liquid sampling and analysis methods. In addition, reaction parameters such as CO2 mass flow rates, temperatures and pressures are seldom recorded, causing the loss of significant information on catalysts, electrodes, and electrolyzers behavior.
To overcome these issues, we assemble a comprehensive analytical system coupling online gas and liquid product analysis by gas and liquid chromatography leveraging a special automated liquid sampling valve with electrochemical protocols that assess CO2RR performance, electrolyzer cell resistance and electrode surface area. In addition, we record CO2 mass flow rates, electrolyzer temperatures, as well as gas and liquid flow pressures.
4 To rapidly and reproducibly handle the large and heterogeneous data volume obtained we implement a standardized data pipeline based on our own open-source software,5 which automatically parses the numerous different raw data files, composes a data set following FAIR practices,6 and post-processes and plots the data in a standardized way. We validate the analytical system by carrying out CO2RR at 200 mA/cm2 on Cu gas diffusion electrodes, following the changes in selectivity with reaction time for > 10 gaseous and liquid products, and recording mass flow rates, electrolyzer temperatures and pressures. The modular nature of our analytical system, combined with the standardized data pipeline, allows us to freely increase the number and type of sensors used with minimal impact on the data analysis time, as well as to multiplex our analysis to 8 parallel electrolyzer cells, paving the way for a much deeper and faster understanding of the function of CO2RR catalysts, electrodes, and electrolyzers.

References

[1] Senocrate, Battaglia, J. Energy Storage
2021, 36, 102373.
[2] Wang, de Araújo, Ju, Bagger, Schmies, Kühl, Rossmeisl, Strasser, Nat.
Nanotechnol.
2019, 14, 1063.
[3] Löffler, Khanipour, Kulyk, Mayrhofer, Katsounaros ACS Catal.
202
0, 10, 6735.
[4] Senocrate, Kraus, Bernasconi, Battaglia, in preparation,
2023.
[5] https://dgbowl.github.io

[5] Kraus, Vetsch, Battaglia, Journal of Open Source Software
2022, 7, 4166.
Effect of pH on the Selectivity of γ-MnO2 Electrocatalysts Towards Oxygen Evolution Reaction in the Presence of Chloride Ions in Alkaline Environment
Authors: Baturina Olga A , Finn Matthew , Weathers Brandice 
Published: August 2024

This paper reports on progress in development of electrocatalysts intended for use in seawater, which optimize the balance of competing reactions between chlorine evolution and oxygen evolution. The oxygen evolution reaction (OER) from H2O is thermodynamically more favorable due to a lower equilibrium potential [1]. However, chlorine evolution successfully competes with the OER due to faster kinetics. One of a few catalysts that demonstrates high selectivity towards the OER in the presence of chloride ions in the alkaline environment (i.e. pH 12) is γ-MnO2 [2].
In this presentation, we (1) compare activities and selectivities towards the OER of electrodeposited and chemically synthesized γ-MnO2 and (2) determine how pH affects selectivity in the pH range from 11 to 13.
g-MnO2 powder was synthesized using hydrothermal method. The synthesis resulted in fabrication of material with a flower-like morphology, characterized by a crystallite size of 5-15 nm and BET surface area of 75 m2/g. In parallel, MnO2 films were prepared by electrodeposition on a Pt RDE substrate, following the procedure outlined by Tsagareli et al. [3]. The electrocatalytic activity of both γ-MnO2 powder and electrodeposited MnO2 was investigated by the thin-film RDE method. The thin films of γ-MnO2 powder were obtained by drop-casting MnO2/VC ink [1] on glassy carbon substrates.
We found that the shape of polarization curves on MnO2/VC films is strongly dependent on the Nafionä loading. At low Nafion loadings, we observe diffusion-limited currents, which we attribute to OH- diffusion through the Nafion. At higher Nafion loadings, neither diffusion-limited currents, nor the currents’ dependence on the rotation rate are observed. Our data indicate that at low Nafion loadings, MnO2/VC films selectively produce O2 in 0.5M NaCl at pH 12 and 13 and current densities up to 15 mA/cm2. Because of the potential effect of Nafion on the permeability of Cl-
ions to the catalyst’s active sites, a set of parallel experiments is being carried out on the electrolytically deposited MnO2 films. The results of the latter experiments will be compared to those obtained on MnO2/VC films in the presentation.
References
[1] F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, P. Strasser, Chemsuschem, 9 (2016) 962.
[2] K. Fujimura, T. Matsui, K. Izumiya, N. Kumagai, H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto, Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 267 (1999) 254.
[3] G. Tsagareli, S. Makhatadze, M. Soselia, N. Maisuradze, Journal of the Indian Chemical Society, 99 (2022).
Advancing Catalyst Performance in Electrochemical Water Splitting
Authors: Zlatar Matej , Cherevko Serhiy 
Published: August 2024

The transition to renewable energy, vital for a sustainable future, frequently encounters challenges such as low energy density and intermittency. A promising solution lies in converting renewable energy into chemical bonds, notably hydrogen, through electrochemical water splitting. This process, however, is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) at the anode. Consequently, this necessitates the use of rare and expensive iridium-based catalysts. Given that iridium is the only metal resilient enough to withstand the harsh anodic conditions of OER, reliance on it poses significant economic challenges, making water electrolysis less competitive compared to fossil fuel-based technologies.
In response to these challenges, our research has two main objectives. First, we aim to understand the often observed trade-off between iridium OER activity and stability. (1) Second, we intent to enhance our understanding of catalyst-support interactions by explore the use of conductive and potentially durable materials as supports for iridium to improve efficiency, a critical yet largely unexplored area.
To achieve these goals, we employ advanced techniques, including inductively coupled plasma mass spectrometry coupled with scanning flow cell. This method enables us to perform detailed potential and time-resolved stability analyses.
Specifically, we conduct an in-depth investigation of the impact of pH across a range from acidic to alkaline environments. Furthermore, we explore a variety of backing electrodes, investigate accelerated stress tests (AST) parameters, (2) and assessing how catalyst loading and Nafion content affect the performance and stability of iridium catalysts.
Our findings provide a deeper understanding of iridium’s stability during OER and highlight the importance of catalyst-support interactions. (3, 4) By addressing the key challenges associated with iridium-based catalysts, this knowledge is crucial for the development of more cost-effective catalysts with minimized use and hence sustainable water electrolysis technologies, marking a step closer to realizing more efficient and economically viable methods for harnessing and storing renewable energy.

References:

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

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

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

R. A. Krivina, M. Zlatar, T. N. Stovall, G. A. Lindquist, D. Escalera-López, A. K. Cook, J. E. Hutchison, S. Cherevko and S. W. Boettcher, ACS Catalysis, 13, 902 (2023).
Porous Bismuth Vanadate Photoelectrodes for Solar Water Oxidation Reaction
Authors: Pattadai Jayaraman Jayanthan , Goldman Benjamin , Harbauer Karsten , Johnson Hannah , Sivula Kevin , van de Krol Roel 
Published: August 2024

Bismuth vanadate (BiVO4), a material known for its high visible light activity and good stability, is a promising candidate as a photoanode for overall water splitting [1]. Its performance is limited by its relatively short charge carrier diffusion length, which has recently been estimated to be ~15 nm [2]. For these kinds of photo-absorbers, commercial flat transparent conducting oxide (TCO) substrates are unsuitable since the thickness needed to absorb a sufficient amount of light far exceeds the carrier diffusion length. With this in mind, deposition of very thin semiconductor film onto the internal structure of (micro)porous, conducting substrates can ensure sufficient light absorption [3], whilst ensuring the individual film thickness is uniformly lower than the carrier diffusion length. Nanostructured TCO substrates can be fabricated using a convenient template-free technique called glancing angle deposition (GLAD). The glancing angle deposition method can be used to synthesize different variations of highly oriented submicron-sized pillars, ranging from vertical and tilted columns to zig-zag and helical structures with the help of shadowing effects and substrate rotation [4]. The optical and electrical properties of nanostructured TCO’s were found to depend on the type of material and the substrate temperature during deposition. We find that pillars made from tin-doped indium oxide show good conductivity (79 Ohm/sq) and are promising for the fabrication of nanostructured substrates for bismuth vanadate. A recently developed alternative approach is the use of transparent, porous, conducting substrates (TPCS) made from quartz felt, in which the quartz fibers are coated with F-doped SnO2 [5]. We found that a BiVO4 film thickness of 50 nm within these porous substrates is enough to absorb the same amount of light as a compact 400 nm bismuth vanadate film. We will discuss the deposition of BiVO4 into the TPCS substrates and the photoelectrochemical performance of these porous photoanodes.
[1] K. Sivula and R. van de Krol, Nat. Rev. Mater. 1, 15010 (2016)
[2] M. Schleuning, M. Kölbach, F. F. Abdi, K. Schwarzburg, M. Stolterfoht, R. Eichberger, R. van de Krol, D. Friedrich, H. Hempel, PRX Energy 1, 023008 (2022)
[3] U. Björksten, J. Moser and M. Grätzel, Chem. Mater. 6, 858 (1994)
[4] M. M. Hawkeye, M. T. Taschuk and M. J. Brett, “Glancing Angle Deposition of Thin Films”, John Wiley & Sons, Ltd., Chichester, UK (2014).
[5] M. Caretti, E. Mensi, R.-A. Kessler, L. Lazouni, B. Goldman, L. Carbone, S. Nussbaum, R. A. Wells, H. Johnson, E. Rideau, J.-h. Yum, K. Sivula, Adv. Mater. 35, 2208740 (2023)