bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen Evolution Catalysts with Iridium Oxide Supported on Doped Titanium Oxide: Role of Dopants on Catalysts Reactivity and Stability
Authors: Cazzulani Elena , Atanassov Plamen , Roiron Camille , Cristiani Pierangela , Chiarello Gian Luca , Zargarian Shabnam 
Published: December 2024

Titanium dioxide (TiO2) is a semiconductor that has been extensively studied for its thermo and photo catalytic properties due to its high stability, abundant oxygen vacancies and low price. In electrochemistry, titanium dioxide has been used as support for anode catalysts in Proton Exchange Membrane Water Electrolysis (PEMWE). The electrolysis of water into oxygen and hydrogen is kinetically limited by the Oxygen Evolution Reaction (OER) occurring at the positive electrode with a four-electron transfer. The noble metal oxides of Ruthenium and Iridium are currently considered the best electrocatalysts for OER due to their high activity and relatively high IrO2 stability [1]. The high price and scarcity of these precious catalysts prompt a strong interest in minimizing their loading [2]. The use of an electronically conductive support allows to decrease the loading by increasing the surface to volume ratio of precious metal particles. Titania is highly stable at the high potentials used during the OER and can be made conductive using some transition metals as dopants [3].
TiO2 exists in nature in three crystalline forms: rutile, anatase, and brookite but because iridium oxide is used for OER in its rutile phase, and to promote epitaxial growth, this work uses the doped-TiO2 rutile phase as a support for Iridium oxide catalysts.
New synthetic routes based on sol-gel process are used to form (Ru, Nb, Ta)-TiO2 nanoparticles. The size, shape and crystalline structure of the support was controlled by tuning calcination temperature and the Ti precursor. The doped rutile TiO2 particles synthesized consist of an ideal support for iridium oxide nanoparticles deposited by wet impregnation in different loading and phase. The epitaxial growth from rutile TiO2 to rutile IrOx promotes the catalyst support interaction and electrical conductivity.
All the catalysts were characterized by their physico-chemical and electrochemical properties towards the oxygen evolution reaction. The surface morphology and crystallinity of these materials was evaluated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The activity toward oxygen evolution reaction was investigated in liquid electrolyte in a 3-electrode set-up.

[1] Alia, S. M.; Rasimick, B.; Ngo, C.; Neyerlin, K. C.; Kocha, S. S.; Pylypenko, S.; Xu, H.; Pivovar, B. S. Activity and Durability of Iridium Nanoparticles in the Oxygen Evolution Reaction. J. Electrochem. Soc 163, 596-603 (2016)

[2] Carmo, M.; Fritz, D. L.; Mergel, J.; Stolten, D. A comprehensive review on PEM water electrolysis. Int. J. Hydrogen Energy 38, 4901– 4934 (2013)

[3] Bauerfeind, K.C.L.; Laun, J., Frisch, M.; et al. Metal Substitution in Rutile TiO2: Segregation Energy and Conductivity.
J. Electron. Mater. 51, 609–620 (2022)
What's the Status Quo of Performance and Durability for Low-Iridium Loadings with Commercial Catalysts in PEM Water Electrolysis?
Authors: Utsch Nikolai , Scheepers Fabian , Aymé-Perrot David , Dubouis Nicolas , Betremieux Isabelle , Müller Martin Johannes , Peters Ralf 
Published: December 2024

Iridium scarcity and the associated challenges for the large-scale deployment of PEM water electrolyzer technology have been addressed in several studies. To meet the targets, several studies have shown that the iridium specific power density needs to be optimized to < 0.10 mgIr W-1.1,2 However, the current state of the art is fuzzy and it's unclear how far we need to go to achieve large-scale deployment of the PEM water electrolyzer. Therefore, we have analyzed four different commercially available catalysts to determine where the current limitations are in realizing large-scale deployment of PEM water electrolysis. Using a common N115 Nafion membrane, we compared the performance for loadings ranging from 0.1 mgIr cm-2 to 0.8 mgIr cm-2 using one catalyst from Alfa Aesar and Umicore together with two catalysts from Heraeus. Sheet resistance was investigated for all loadings and catalysts and correlated with corresponding high frequency resistance and performance. Durability was evaluated using a bottom-up approach, starting with the lowest loading and a total test time of 500 h. With the data presented, we shed light on the current state of the art for low iridium loading in PEM water electrolysis.
Literature

Minke, C., Suermann, M., Bensmann, B. & Hanke-Rauschenbach, R. Is iridium demand a potential bottleneck in the realization of large-scale PEM water electrolysis? Int. J. Hydrog. Energy
46, 23581–23590 (2021).

Clapp, M., Zalitis, C. M. & Ryan, M. Perspectives on current and future iridium demand and iridium oxide catalysts for PEM water electrolysis. Catal. Today
420, 114140 (2023).
Shape-Controlled Iridium Catalysts for OER in PEM Electrolysis
Authors: Xu Heng , Wang Xiaojing , Spendelow Jacob S. 
Published: December 2024

Hydrogen is a clean energy carrier that holds the potential to power future transportation.1 One way to generate green hydrogen is proton exchange membrane (PEM) electrolysis with renewable electricity, but this process is limited by the sluggish oxygen evolution reaction (OER).2, 3 Iridium (Ir) catalysts have balanced activity and durability for OER.4, 5 However, due to the scarcity and high cost, the structures of the Ir catalysts must be properly controlled to improve the catalyst performance and reduce Ir loading.6, 7 Currently, most Ir catalysts are nanoparticles without well-defined crystal facets, and it remains largely unknown what Ir surface structure is the most effective for OER.4 Here, we present the facet-selective growth of Ir catalysts by using various shape-controlled seeds. These shape-controlled Ir catalysts exhibit high Ir atom usage efficiency due to the formation of only a few atomic layers of Ir shells. The activity and durability of these shape-controlled Ir catalysts towards OER are evaluated by rotating disk electrode measurements and tested in a PEM electrolyzer. This work demonstrates the possibility to further improve Ir catalyst performance by precise control over the arrangements of catalyst surface atoms.

Acknowledgments

We acknowledge the funding support from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) (20240061DR) and the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE).

References

(1) Debe, M. K. Electrocatalyst approaches and challenges for automotive fuel cells. Nature
2012, 486, 43-51.
(2) Wang, Y.; Pang, Y.; Xu, H.; Martinez, A.; Chen, K. S. PEM Fuel cell and electrolysis cell technologies and hydrogen infrastructure development – a review. Energy Environ. Sci.
2022, 15, 2288-2328.
(3) An, L.; Wei, C.; Lu, M.; Liu, H.; Chen, Y.; Scherer, G. G.; Fisher, A. C.; Xi, P.; Xu, Z. J.; Yan, C.-H. Recent Development of Oxygen Evolution Electrocatalysts in Acidic Environment. Adv. Mater.
2021, 33, 2006328.
(4) Wang, S.; Shen, T.; Yang, C.; Luo, G.; Wang, D. Engineering Iridium-Based Oxygen Evolution Reaction Electrocatalysts for Proton Exchange Membrane Water Electrolyzers. ACS Catal.
2023, 13, 8670-8691.
(5) Gao, J.; Liu, Y.; Liu, B.; Huang, K.-W. Progress of Heterogeneous Iridium-Based Water Oxidation Catalysts. ACS Nano
2022, 16, 17761-17777.
(6) Alia, S. M.; Pylypenko, S.; Neyerlin, K. C.; Kocha, S. S.; Pivovar, B. S. Activity and durability of iridium nanoparticles in the oxygen evolution reaction. ECS Trans.
2015, 69, 883-892.
(7) Alia, S. M.; Shulda, S.; Ngo, C.; Pylypenko, S.; Pivovar, B. S. Iridium-Based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts. ACS Catal.
2018, 8, 2111-2120.
Unveiling and Mitigating the Instability of Noble Metal-Free Oxide Electrode for PEM Water Electrolysis
Authors: Wang Jian 
Published: December 2024

Developing many sustainable energy technologies (e.g., H2O and CO2 splitting) warrants accelerating the sluggish oxygen evolution reaction (OER) efficiently and economically. However, designing noble-metal-free electrocatalysts (NMFEs) to replace noble-metal-based OER electrocatalysts is tremendously challenging in acidic electrolytes where chemical corrosion is conventionally regarded as a bottleneck factor. So far, few NMFEs reported can be an alternative to Ru-/Ir-based catalysts for acidic OER. Differernt from conventional wisdom, through monitoring the dynamics of the catalytic process during water electrolysis, we unambiguously demonstrated that electrochemical reconstruction instead of chemical corrosion dominantly degraded the OER performance of typical Mn and Co oxides as resentative NMFEs. Based on the uncovered degradation mechanism, we further developed a novel and rational method to overcome the problem of activity-stability trade-off faced by various OER electrocatalysts. Correlative operando characterizations found that our modulation method successfully suppressed the undesired surface reconstructions by mitigating the cationic/anionic redox and catalyst leaching, and meanwhile atomistic calculations revealed that the synergy of dual sites generated more favorable catalytically-active species. The resultant noble-metal-free oxide yielded a record performance among reported NMFEs, and its superior performance was also validated by the PEM water electrolyzer. This work will provide a critical reference for designing NMFEs for PEM water electrolysis.
Reference:
1. Jian WANG*, Controlling dynamic reconstruction chemistry for superior oxygen-evolving catalysts, Chem, 2023, 9 (7), 1645-1657.
2. Jian Wang,* Ying Wang, Junsik Cho, Ting-Shan Chan, Yang Ha, Shu-Chih Haw, Cheng-Wei Kao,Yunze Zhang, Jiayi Tang,Jia Lei,Tong Liu,Siyuan Zhao, Yawen Dai, Aleksandra Baron-Wiechec, Fu-Rong Chen, Wenxiong Wang, Chang Hyuck Choi, Zongping Shao, Meng Ni, Under revision. 2024.
Tuning the Hydrophilicity of Polymers for Ion-Solvating Membranes for Alkaline Electrolysis
Authors: Jensen Jens Oluf , Serhiichuk Dmytro , Rajappan Sinu Charamchirail , Xia Yifan , Kraglund Mikkel Rykær , Aili David 
Published: December 2024

Ion-solvating membranes constitute an alternative to both porous diaphragms and anion-exchange membranes for alkaline electrolysis. [1,2] The underlying principle is to imbibe a nonporous hydrophilic membrane with concentrated aqueous KOH and thus obtain high ionic conductivity from the sorbed electrolyte. It is well-established that high ionic conductivity can be reached, [3] and the main challenge is to identify or develop polymers with the right affinity for aqueous KOH and with long-term stability in the aggressive environment. Polymers known for their alkaline stability are generally hydrophobic and will not take up KOH. One strategy to promote and control the KOH uptake is to tune the polymer hydrophilicity to the extent that enough KOH is sorbed without dissolving the polymer. [4]
The paper presents recent progress with hydrophilicity adjustment of polymers by hydrophilic functionalities. Hydrophilic tetrazole moieties are particularly stable in the alkaline environment due to deprotonation at high pH and the resulting formation of a negative charge that repels the aggressive hydroxide ions. See Figure 1. It is easy to adhere to the backbone by a click reaction. Chemical stability screening, electrolyte uptake, ion conductivity, and initial electrolyzer tests are presented.
-

References

[1] D. Aili, M. R. Kraglund, S. C. Rajappan, D. Serhiichuk, Y. Xia, V. Deimede, J. Kallitsis, C. Bae, P. Jannasch, D. Henkensmeier and J. O. Jensen. Electrode Separators for the Next-Generation Alkaline Water Electrolyzers. ACS Energy Lett. 8 1900-1910 (2023). DOI: 10.1021/acsenergylett.3c00185
[2] D. Henkensmeier, W. Cho, P. Jannasch, J. Stojadinovic, Q. Li, D. Aili and J. O. Jensen. Separators and membranes for advanced alkaline water electrolysis. In press, Chemical Reviews. DOI: 10.1021/acs.chemrev.3c00694
[3] M. R. Kraglund, M. Carmo, G. Schiller, S. A. Ansar, D. Aili, E. Christensen and J. O. Jensen. Ion-solvating membranes as a new approach towards high rate alkaline electrolyzers. Energy Environ.
Sci. 12, 3313 – 3318 (2019). DOI: 10.1039/c9ee00832b
[4] D. Serhiichuk, S. Rajappan, Y. Krishnan, Y. Xia, M. R. Kraglund, H. A. Hansen, J. O. Jensen and D. Aili. Tetrazole functionalization: A new strategy toward stable ion-solvating polymer electrolytes for alkaline water electrolysis. Submitted. DOI: 10.26434/chemrxiv-2024-29p7m
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Figure 1. Tetrazole functionalization of poly(styrene-co-acrylonitrile) (SAN) followed by formation of the corresponding potassium tetrazolide. [4]

Figure 1
Investigating Ionomer Interactions on the Catalytic Interface of Model Catalysts (NiO, IrO2)
Authors: Ha Mai-Anh , Leitner Oliver , Isakov Avital , Larsen Ross E , Volk Emily K. , González Héctor , Alia Shaun M 
Published: December 2024

Anion exchange membrane electrolysis enables the use of earth abundant metals for the catalyst and other components of the membrane electrode assembly. However, earth abundant metal catalysts may be sensitive to poisoning and degradation due to the extreme pH of the electrolyte or interactions with the ionomer. Plane-wave density functional theory calculations probed the binding strength of different functional groups from popular ionomers (Nafion, Sustainion, tetramethylammonium-based ETFE/Gen 2/Georgia Tech, Versogen) on model catalysts such as Platinum Group Metal IrO2 and earth abundant NiO.1 We evaluated the stability of these various ionomers on these model catalysts, whether they remain intact or degrade, as well as their catalytic effects on the oxygen evolution reaction (OER) e.g. in the presence of OH*. These calculations allowed us to understand the poisoning of active sites: 1) if the functional group bound more strongly than key reaction intermediates, then the ionomer effectively blocked activity by displacing the reaction intermediate; 2) if the functional group introduced competing reactions, then the ionomer was consuming the OxHy* intermediates necessary for OER. Ideally, ionomers remain stable in contact with the catalyst and shuttle hydroxide ions from the cathode to the anode.
1. S. Ghoshal, B. S. Pivovar and S. M. Alia, J. Power Sources, 2021, 488, 229433.

Figure 1
Molecular Engineering of Ion-Conducting Polymer Membranes: Synthesis, Properties, and Applications
Authors: Bae Chulsung 
Published: December 2024

Ion-conducting polymers (e.g., proton and hydroxide) are used as polymer electrolyte membranes, and they are a key component of electrochemical energy conversion and storage technologies such as fuel cells, electrolyzers, and flow batteries. For example, hydrogen fuel cell and water electrolyzer industry also heavily relies on Nafion for a proton-conducting membrane for decades, though it is not ideal proton-conducting membrane material for those applications.
Perfluoroalkyl substrates (PFASs), which include Nafion, have recently received significant pressure from government and environmental activist groups due to their environmental and health hazard of PFAS. Thus, the development of alternative ion-conducting polymers based on hydrocarbon polymers (mostly made of C and H) has attracted new attention within polymer society. Compared to perfluorosulfonated Nafion, hydrocarbon ion-conducting polymers can offer advantages of flexible synthetic tunability, lower gas permeability, and importantly lower production cost. However, their systematic polymer chemistry–morphology structure–property relationships are poorly understood until now.
In this presentation, we describe an overview of recent progress in the development of advanced ion-conducting (H+ and OH–) polymers, key membrane properties, and their state-of-the-art performance in in real world applications of hydrogen fuel cells and water electrolyzers.[1,2]

References

[1] S. Adhikari, M. K. Pagels, J. Y. Jeon, C. Bae* “Ionomers for Electrochemical Energy Conversion & Storage Technologies”, Polymer (Perspective Special Issue celebrating the 100 years "From ‘Makromolekel' to POLYMER”), Polymer, 2020, 211, 123080.
[2] S. Noh, J. Y. Jeon, S. Adhikari, Y. S. Kim, C. Bae* “Molecular Engineering of Hydroxide Ion Conducting Anion Exchange Polymers for Electrochemical Energy Conversion Technology” Acc. Chem. Res.
2019, 52, 2745–2755.
Elucidating Hydroxide Transport through Utilization of Asymmetric Feed System: Advancing Towards Pure Water and Vapor Anion-Exchange-Membrane Electrolysis
Authors: Metem Prattakorn , Petrovick John G. , Eriksson Björn , Lindbergh Göran 
Published: December 2024

Anion-exchange-membrane water electrolysis (AEMWE) is a nascent green hydrogen production technology. Its main advantage lies in its ability to utilize non-platinum group metals (PGMs) as catalysts and PFSA-free polymer as a membrane, unlike proton-exchange-membrane water electrolysis (PEMWE). It is well-known that, unlike PEMWE, AEMWE suffers greatly from substituting the electrolytic feed solution with a solution of a lower pH (e.g., pure water). Literature has attributed the loss of performance to the lower reaction kinetics of both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) and the drastic loss of electrolyte conductivity, which is further exacerbated at higher current density [1]. Notably, it is shown that addition of salt to improve the conductivity of electrolyte does not always equate to a better performance over time, depending on the feed configuration, highlighting the importance of understanding mass transport during cell operation [2]. Therefore, to decouple the causes of the drastic losses of performance in-situ, we have developed a system capable of feeding vapor and liquid into AEMWE asymmetrically. The cell is constructed using a membrane electrode assembly (MEA) fabricated by the catalyst coated membrane (CCM) method, where platinum on carbon (Pt/C) and iridium oxide (IrOx) are coated directly on PiperION® anion exchange membranes. Moreover, we have studied hydroxide crossover both statically using an h-cell test and dynamically in an AEMWE cell. We have shown that, by utilizing various combinations of feeds, including humidified gas, pure water, or KOH, through both cathode and anode, it is possible to study cell performance and hydroxide transport under different conditions. Through which, we have elucidated the performance loss, the importance of hydroxide transport, and a strategy to overcome such losses, thus showing the possibility of advancing toward pure water and low-temperature vapor electrolysis.
[1] Liu, Jiangjin, et al. "Elucidating the role of hydroxide electrolyte on anion-exchange-membrane water electrolyzer performance." Journal of the electrochemical society 168.5 (2021): 054522.
[2] Rossi, Ruggero, Rachel Taylor, and Bruce E. Logan. "Increasing the electrolyte salinity to improve the performance of anion exchange membrane water electrolyzers." ACS Sustainable Chemistry & Engineering 11.23 (2023): 8573-8579.
Figure 1. Schematic of the developed feeding system capable of feeding water vapor and liquid into the electrolyzer.

Figure 1
Electrochemical Activity of Oxygen in Li-Ion Battery Cathodes from X-Ray Spectroscopic Modeling
Authors: Lomeli Eder , Hsu Sean , Kas Josh Jason , Vinson John , Rehr John , Moritz Brian , Yang Wanli , Devereaux Thomas P. 
Published: December 2024

As demand for better performance in energy storage increases, a clear understanding of the charge compensating mechanism in Li-ion battery cathodes is essential for developing next generation battery chemistries and materials. X-ray core level spectroscopies, e.g. x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS), allow for experimental measurement of the electronic structure of battery materials before and after charge, providing the clearest physical picture of electrochemical device operation.
Here, we present numerical modeling of the XAS/RIXS of various battery chemistries compared to experimental measurements in situ. Modeling spectroscopic changes before and after discharge using not only density functional theory (DFT) based techniques but also exact diagonalization atomic multiplet formalisms prove crucial in these materials to accurately model correlation effects seen in their spectra, where reversible changes in the transition metal L3-edge spectroscopy may erroneously point to cationic redox. We address the common concept of transition metal redox, highlight the essential role of oxygen in both reversible and irreversible processes, and the break down in the standard paradigm of cationic/anionic redox.
Screening the Dynamic Behavior of the Electrode-Electrolyte Interphase on Hard Carbon Via Scanning (Electrochemical) Probe Microscopy
Authors: Kranz Christine , Daboss Sven , Saleh Salimeh , Palanisamy Krishnaveni 
Published: December 2024

Hard carbon is an attractive anode material for alkali-ion batteries, particularly for sodium-ion batteries (SIBs), due to the high storage capacity and the fact that HC can be produced from renewable bio-resources1. Similar to lithium-ion batteries (LIBs), the performance and operational stability of SIBs is dependent on the electrode electrolyte interface (SEI)2. Although, the SEI on graphite anodes (LIBs) and HC anodes (SIBs) have similar chemical properties, it has been shown that the SEI of SIBs is less stable and its stability is strongly dependent on the experimental conditions3. For example, we have recently investigated the SEI formation on spray-coated HC composite anodes in half-cell configurations in dependence of the electrolyte (ester and ether based including studies in the presence or absence of fluoroethylene carbonate (FEC) as an additive). Using scanning (electrochemical) probe microscopy (SEPM), such as scanning electrochemical microscopy (SECM), atomic force microscopy (AFM) and hybrid AFM-SECM, we could characterize the electrochemical and nanomechanical properties of the SEI4
-6.
In this contribution, we present SEPM such as scanning electrochemical cell microscopy (SECCM)7, which has been used as attractive SPM technique for battery research8,9. SECCM is used to locally form SEI layers under different experimental conditions at the surface of HC composite anodes. The advantage of this approach is that on the same electrode surface e.g., different number of charge and discharge cycles can be performed forming localized SEI spots. These spots are then investigated by AFM and AFM-SECM to study the electrochemical and nanomechanical properties as well as dynamic behaviour such as the dissolution or possible swelling. Advantages and challenges of this in situ characterization of the formed interphases at post-Li battery electrodes are discussed.

Acknowledgement

This work contributes to the research performed at CELEST (Center for Electrochemical Energy Storage Ulm - Karlsruhe) and was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2154 – Project number 390874152 (POLiS Cluster of Excellence).

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60, 4855–4863, 2021.
[4] K. Palanisamy et al.,Batt. & Supercaps 7, e202300482, 2024.

[5] K. Palanisamy et al.,Batt. & Supercaps 7, e202300402, 2024.

[6] S. Daboss, T. Philipp, K. Palanisamy, J. Flowers, H.S. Stein, C. Kranz, Electrochim. Acta 453, 142345, 2023.
[7] D.Martín-Yerga, M. Kang, P. R. Unwin, ChemElectroChem 8, 4240 – 4251, 2021.
[8] S. Daboss, F. Rahmanian, H. S. Stein, C. Kranz, Electrochem. Sci. Adv. 2, e2100122, 2021.
[9] E. Ventosa, Curr. Opinion Electrochem. 25, 100635, 2021.