bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Ru-Based PEM Electrolysis Catalyst – Development from the Nano- to the Industrial-Scale
Authors: Gebauer Christian , Marić Robert , Bulic Matej , Ashley Mike , Swisher Jordan 
Published: August 2024

For the de-fossilization of sectors like chemicals, steel, and transportation, green H2 generated via water electrolysis provides a path towards net-zero. The broad use of H2 across hard-to-abate sectors confirms the urgent need for green hydrogen at scale.
Within water electrolysis, there are several competing technologies: the so-called solid oxide electrolysis cell (SOEC), alkaline water electrolysis (AEL) and polymer electrolyte membrane electrolysis (PEM EL). Here, the latter shows significant benefits, such as high current density operation (> 2 A/cm2) and thus a smaller footprint, highly dynamic operation mode, high gas purity, and generation of pressurized hydrogen. However, at present, PEM EL requires precious metal catalysts; in particular, the O2 evolution on the anode currently relies on iridium, a metal which is rather scarce and expensive [1].
To meet the demand of iridium with respect to the announced increase in electrolyzer capacities in the multi-GW range, material innovation to reduce the use of this precious metal must be implemented. Successful catalyst and electrode developments have already been demonstrated in the BMBF funded project Kopernikus P2X, whereby loadings of approx. 0.3 mg/cm2 (< 0.1 g/kW1) have been achieved without any significant losses in activity over time [2, 3].
Here, we present a material innovation in the form of Ru-based electrocatalysts with a significantly reduced Ir content. This ruthenium-iridium oxide can be adjusted in a wide range of Ir content down to less than 15 wt.% (Ir). Consequently, iridium-based electrode loadings of less than 0.1 mg/cm2 and mass activities of about 3,500 A/g are feasible. Moreover, in accelerated degradation tests those mixed-oxides have demonstrated the often-missing stability by showing low degradation rates, similar to that of pure IrO2, in up to 30,000 potential-induced stress cycles.
This achievement stems from a remarkable screening approach that combines synthesis, characterization and testing at the nanoscale at Mattiq, and on industrial scale in the multi-gram range at Heraeus Precious Metals GmbH & Co. KG. Remarkably the alignment of degradation testing on both scales showcases the power of the applied method, providing a blueprint for high throughput screening for future material developments, both within water electrolysis and beyond.
References
[1] “Iridium Quaterly Market Report“, SFA Oxford (2021) 31
[2] M. Bernt, A. Hartig-Weiß, M.F. Tovini, H.A. El-Sayed, C. Schramm, J. Schröter, C. Gebauer, H.A. Gasteiger, Chem. Ing. Tech. 92, 31 (2020)
[3] M. Möckl, M.F. Ernst, M. Kornherr, F. Allebrod, M. Bernt, J. Byrknes, C. Eickes, C. Gebauer, A. Moskovtseva, H.A. Gasteiger, J. Electrochem. Soc. 169, 064505 (2022)
(Invited) Development of Ir-Based Electrocatalyst for Proton Exchange Membrane Water Electrolysis
Authors: Ito Mizuki 
Published: August 2024

PEMWE (proton exchange membrane water electrolysis) is one of the most prospective way to produce hydrogen without environmental damage. So far, various materials have been studied for more efficient water electrolysis. These studies have mainly focused on anode-side material since the over potential for the anode side reaction (H2O → 1/2O2 + 2H+ + 2e-) is much higher than that of the cathode side reaction (2H++2e- → H2).
Among various materials, iridium oxide (IrOx, IrO2) is one of the most superior anode side material. As a company, which address PGM (platinum group metal) and their technologies, we have been developing the iridium-based catalyst for PEMWE.
We have TEC77100, TEC77110 etc. as catalyst line-up for water electrolysis. TEC77100 is an amorphous-type iridium oxide catalyst with large surface area which reaches about 100 m2 g-1, whereas, TEC77110 is a crystalline (rutile) -type catalyst with high durability. The amorphous-type TEC77100 shows higher activity (–1.86 V@2A cm-2, 50°C, measured in MEA with NafionTM 115 membrane) than the rutile-type TEC77110 (–1.92 V@2A cm-2, 50°C). In terms of durability, however, TEC77110 is superior to TEC77100. The degradation was suggested to be due to the crystallization of TEC77100 under water electrolysis condition. Except for these two types of catalyst, I’ll also introduce a catalyst to countermeasure cross leaking hydrogen in the anode side from the cathode side briefly.

Figure 1
(Invited) Hierarchically Structured Electrocatalysts Using Scalable Synthesis Techniques for Membrane Water Electrolyzers
Authors: Peron Jennifer 
Published: August 2024

Beyond composition, the morphology of catalyst particles is a key-parameter to allow for a high accessibility to catalytic sites but it is also of paramount importance to manage gases and water transport within catalyst layers in membrane-electrode assembly based devices. Besides their electrochemical activity, fabricating high performance catalysts and catalyst layers that are compatible with industry fabrication processes is critical for their implementation in commercial electrochemical devices. Considering these requirements, we are developing green, cheap and scalable solution synthesis techniques to prepare hierarchically structured catalysts that can be readily incorporated into catalyst layers.
Two strategies will be discussed. We have recently introduced an aerosol synthesis technique for the preparation of highly porous iridium pure and mixed oxides that are highly active and stable towards the Oxygen Evolution Reaction in acidic media. Beside beeing ideally suited for the preparation of highly porous catalyst layers, the hierarchical morphology can also be used for fundamental studies [1] or used as a probe to follow the catalyst degradation in PEM water electrolysis devices.[2]We also implemented the well-known polyol process [3] to prepare heterofunctional catalysts with ultra-low PGM content that are active towards another challenging reaction in anion exchange membrane water electrolyzer: the Hydrogen Evolution Reaction in alkaline media. The structure-properties relationship in these materials is assessed by a large set of techniques including SEM, XRD, XRF and STEM-EDX as well as surface (XPS) and bulk (XAS) characterizations, including operando XAS.

Nature Communications,
2021, 12, 3935, 1038/s41467-021-24181-x

Chemistry of Materials,
2023, 35, 20, 8590–8598,
1021/acs.chemmater.3c0152.

Chem. Soc. Rev.
, 2018, 47, 5187-5233,
10.1039/C7CS00777A
Exploring the Role of Coordinating Environments on Durability of Nickel-Based Catalysts for Hydrogen Evolution Reactions
Authors: Yang Kevin , Friedman Ariel , Mukerjee Sanjeev 
Published: August 2024

Ni-based platinum-group-metal (PGM)-free catalysts for hydrogen evolution reaction have been considered viable for the commercialization of alkaline exchange membrane water electrolysis (AEMWE) due to their high activity and low cost. Even though several highly active Ni-based catalysts have been developed in recent years, their long-term stability under commercially relevant conditions was not systematically assessed, preventing a direct comparison with the currently used catalysts. While not as active, the current commercial PGM-free catalysts are highly stable, with an operational life measured in decades. However, conducting durability assessments through long-term durability studies can take over 10,000 hours which is impractical. Consequently, accelerated stress tests (ASTs) specifically targeting the catalyst and simulating uncontrolled shutdown and high overpotential scenarios are needed to further improve AEMWE technology.
In this presentation, the ASTs of several Ni-based catalysts with different coordination environments (nickel molybdenum, nickel cupferron1, Ni-NiO, and a novel high surface area de-alloyed Ni catalyst) will be explored. The catalysts were subjected to high overpotentials and uncontrolled shutdown cycles in both liquid electrolyte and AEMWE cells. The structure of these catalysts was observed using in situ Raman spectroscopy, XRD, TEM, and BET gas adsorption analysis and correlated to changes in electrochemical performance. The determination of the catalyst structure during these ASTs is paramount in designing durable PGM-free catalysts for improved AEMWE performance.
1) Doan, H.; Kendrick, I.; Blanchard, R.; Jia, Q.; Knecht, E.; Freeman, A.; Jankins, T.; Bates, M. K.; Mukerjee, S. Functionalized Embedded Monometallic Nickel Catalysts for Enhanced Hydrogen Evolution: Performance and Stability. J. Electrochem. Soc.
2021, 168 (8), 084501. https://doi.org/10.1149/1945-7111/ac11a1.
Understanding the Reaction Activity of Ni(1-x)FexOH Towards Oxygen Evolution Reaction
Authors: Costa Figueiredo Marta 
Published: August 2024

The development of electrocatalysts towards the oxygen evolution reaction based on earth-abundant and cheap materials, such as transition metal oxide and hydroxide, is crucial to reduce the emission of CO2 and slowdown the global warming [1]. Among these transition metal compounds, ferromagnetic electrocatalysts usually exhibit promising activities towards OER due to their unique electron spin properties [2]. Applying an external magnetic field can further tune the electron spin polarization of ferromagnetic materials and, therefore, improve the OER activity. However, evaluating the activity of these electrocatalysts towards OER remains challenging. For example, the electrocatalysts will undergo activation under reaction conditions (frequently due to Fe insertion), which brings difficulties in determining the real reaction sites as well as establishing the “structure-activity” relationship [3]. In addition, the overall measure activity (current density) is contributed by multiple factors such as intrinsic kinetics, mass transfer, conductivity, etc., which strongly depend on operation conditions. In this talk, I will present our recent study of OER on Ni(1-x)FexOH [4]. Electrochemical impedance spectroscopy (EIS) and quasi-in situ XPS will be applied to obtain the contribution from different reaction parameters and understand the intrinsic activity.
[1] McCrory, C. C. L. et al. Benchmarking Hydrogen Evolving Reaction and Oxygen Evolving Reaction Electrocatalysts for Solar Water Splitting Devices. Am. Chem. Soc.
137, 4347–4357 (2015).
[2] Ren, X. et al. Spin-polarized oxygen evolution reaction under magnetic field. Commun.
12, 1–12 (2021).
[3] Jung, S., McCrory, C. C. L., Ferrer, I. M., Peters, J. C. & Jaramillo, T. F. Benchmarking nanoparticulate metal oxide electrocatalysts for the alkaline water oxidation reaction. Mater. Chem. A
4, 3068–3076 (2016)
[4] Wei Chen, Laura Donk, Tiago Fernandes, Anna Kitayev, ErvinTal Gutelmacher, Yury V. Kolen’ko, Marta C. Figueiredo*, in preparation.
Diagnosis of Voltage Losses of the Proton Exchange Membrane Water Electrolyzer with Nonlinear Frequency Response Method
Authors: Milicic Tamara , Muthunayakage Kasun , Vu Hoang Thanh , Zivkovic Luka A. , Ritschel Tobias Kasper Skovborg , Vidakovic-Koch Tanja 
Published: August 2024

Proton exchange membrane water electrolyzer (PEMWE) takes a central place in the hydrogen economy as a crucial technology for green hydrogen production. However, this technology still faces challenges, such as the cost of the materials, performance losses at high current densities, and durability. To overcome these obstacles, better comprehension of the phenomena occurring in the PEMWE is necessary. Typical electrochemical methods, such as polarization curves and high-frequency response measurements, lack detailed information about the individual contributions to the overall voltage losses and cannot point out the causes of the performance shortcomings. Therefore, the development of advanced diagnosis techniques for PEMWE is of importance both for the state of health analysis during the operation, as well as for the testing of new materials.
In this work, a nonlinear frequency response (NFR) method was applied for the diagnosis of a lab-scale PEMWE. The NFR method represents an extension of the electrochemical impedance spectroscopy to the nonlinear domain by investigating the second-order frequency response function (FRF) in addition to the first-order FRF (equivalent to the impedance) [1]. Typical features corresponding to processes occurring in the PEMWE were observed in both the first- and the second-order FRFs. The experimental observations were interpreted based on a simple nonlinear model. The features observed at frequencies higher than 0.1 Hz were attributed to the electrochemical half-reactions, while a high current density feature observed at lower frequencies, could be attributed to the mass transport. During the analysis, the first-order FRF (impedance) was found not to be sensitive enough for the discrimination of the different sets of parameters and the second-order FRF had to be included for better parameter identification. The obtained parametrized model is dynamic and nonlinear and, thus, it can be utilized for model predictive control of the PEMWE and optimization of the overall green hydrogen production system.
[1] Vidaković-Koch, T., Miličić, T., Živković, L.A., Chan, H.S., Krewer, U., Petkovska, M., Cur. Opin. Electrochem., 2021, 30, 100851
Measuring Charge Selective Contacts on Semiconducting Photocatalyst Particles
Authors: Kaufman Aaron James , Boettcher Shannon W. , Shen Meikun 
Published: August 2024

Water splitting could replace steam-methane reforming, a carbon intensive process, to generate hydrogen for energy storage, fertilizer production, and many other industrial processes. Photoelectrochemical (PEC) overall water splitting (OWS), for example, produces hydrogen from water, without wires or applied voltages, via a clean and renewable energy source, sunlight. To do so, PEC particles or photocatalysts (PC) must absorb light, and selectively collect the generated carriers, either electrons or holes, at specific sites which drive reduction or oxidation reactions, respectively. While theoretical solar to hydrogen (STH) efficiencies are at least 18%, state-of-the-art PCs are below 3%. Despite the extreme efforts screening and tuning semiconductor photocatalysts, a thorough understanding and control of electronic properties of the semiconductor-electrocatalysts (sem|cat) interface is limited.
Here, we use advanced electrochemical methods (dual-working electrode), scanning probe microscopy (conductive-AFM) and ambient-pressure XPS to measure and understand the origins of the electrochemical driving force (gradient in electrochemical potential) developed at complimentary electrocatalysts on photocatalyst particles. We use the dual-working electrode geometry on a high-quantum-yield wide-bandgap perovskite oxide, SrTiO3, to demonstrate the adaptive nature of electrocatalysts, Pt and CoOx, as they accumulate electrons and holes respectively. The cooperativity of half-reaction kinetics and adaptive sem|cat barrier height will be demonstrated along with the influence of crystal termination, which we argue is commonly overemphasized. Finally, a new contactless method of measuring the photovoltage at chemically distinct catalysts sites will be presented. Measured photovoltage induced shifts to element specific core levels in ambient pressure XP spectra in the dark and under illumination directly probe interfacial mechanisms operando. In sum, the introduced techniques and their findings demonstrate the underlying mechanisms and the degree that they play, enabling directed research of photocatalyst systems under one dominant engineering condition, charge selective

Figure 1
(Invited) Ternary Oxide Semiconductors and Alloys for Photoelectrochemical Applications: Hope and Reality
Authors: Rajeshwar Krishnan , Rawat Abhishek , Danladi Fahad 
Published: August 2024

This perspective talk focuses on the history and status of new materials with targeted application in solar energy conversion. Specifically, photoelectrochemical energy conversion/solar water splitting and wide bandgap oxide semiconductors and alloys for solar windows and displays are the two targeted application areas. The Cu-M-V-O family of oxide semiconductors will be discussed in this talk. Both synthetic aspects and chemical composition-property-performance correlations will be presented.
Acknowledgements. This work was primarily supported by the National Science Foundation UTA/NU Partnership for Research and Education in Materials (NSF DMR-2122128).
Adjusting the Catalytic Performance of MIL-88B(Fe/Co) through Structural Transitions
Authors: He Xiang 
Published: August 2024

Metal-organic frameworks (MOFs) are a family of highly porous materials, which are composed of metal-based nodes and organic ligands. Thanks to the large surface areas and tunable chemical functionalities, MOFs are emerging as excellent catalysts for the sector of renewable energy. Of particular interest, the structures of certain MOFs are highly flexible, allowing for reversible structural transitions upon the stimuli from various external sources. Such stimuli-responsive behaviors of MOFs create new opportunities to design functional materials for switchable catalysis. Nevertheless, the exploration of the flexible MOF-based catalysts is still at a nascent stage. Herein, to advance the fundamental understanding of how the dynamic behaviors of flexible MOFs could affect the catalytic performance, first-principles calculations were carried out using the density functional theory, where a bimetallic MOF, MIL-88B(Fe/Co), was selected as a model structure. Results showed that the lattice contraction can result in twisted ligands as well as the rotary metal nodes, which subsequently lead to variations of the free energy diagrams for the oxygen evolution reaction, demonstrating the critical role of structural flexibility in determining the energy barriers during the elementary steps. Further analysis using the pair distribution function and electron localization function confirmed the rigid short-range order of MOFs during the structural transitions, as well as the tunable guest-host interactions upon lattice contraction/expansion, which could be responsible for the observed differences in the energy barriers during catalysis. Overall, the findings from this work offer new insights into the catalyst design for the modulated production of renewable fuels.
Reference: CrystEngComm, 2023, 25, 6441 - 6448
(Invited) Changes in Electric Double-Layer Structures Under Localized Surface Plasmon Excitation
Authors: Minamimoto Hiro , Shiga Futa , Mizuhata Minoru 
Published: August 2024

For the visible light energy conversion, the localized surface plasmon resonance (LSPR), which is the collective oscillations of free electrons, should be promising. With the excitation of LSPR, the highly localized electric field generates in the vicinity of metal nanostructures. It is interesting that various unique photo-response properties, such as chemical reactions or molecular excitations, can be observed due to the enhancement of light-matter interaction.[1] To understand and control such mediated chemical reactions or electrochemical reactions, the precise understanding about the electrified interfaces of plasmonic nanostructures should be required.
Especially in the electrochemical system, the electric double layer is formed due to the difference in electrochemical potential between the metal interface and solution. The study of the surface potential is important for the design of chemical reactions because the surface potential at the liquid-solid interface is dependent on the physical properties of the systems. The zeta potential which is the potential of the slipping surface near the Stern layer of the diffusion layer could provide such information. From this point of view, in this study, we investigated the electric double-layer structures through the examination of the zeta potential under LSPR excitation condition. To obtain the zeta potential, we have performed the streaming potential method using Au nanoisland structures under visible light illuminations to excite the LSPR. It was interesting that the zeta potential was drastically changes under the visible light illumination conditions. This zeta potential change indicates the changes in the electric double layer structures through the excitation of LSPR. Through the investigations of incident wavelength dependence or the substrate dependences, the effects for the LSPR excitations on the electric double layer structure have been revealed. The present work would provide the fundamental knowledge about the effect on the LSPR excitation at solid-liquid interfaces.
[1] H. Minamimoto et al., Acc. Chem. Res., 2022, 55(6), 809.
Elucidating Degradation of Aqueous Organic Redox Flow Batteries by Electrochemical Impedance Spectroscopy
Authors: Zeng Chao , Kim Soowhan , Fu Yucheng , Chen Yunxiang , Bao Jie , Xu Zhijie 
Published: August 2024

Redox flow batteries, facilitating the dissociation of energy and power, emerge as a promising avenue for electrochemical electricity storage. A shift from vanadium flow batteries to those employing aqueous organic electroactive species is evident due to the latter's advantageous features, such as diverse design possibilities through functionalization, reduced cost, non-toxicity, and improved availability. Despite expectations that organic redox flow batteries can surpass a lifespan of 10 years or 2000 cycles, their practical long-term performance faces challenges arising from electrode, membrane, and organic species degradation.
The intricate interplay of various degradation factors during full cell cycling results in observable capacity decay over cycles. Effectively mitigating degradation necessitates the dissection of these factors to identify the limiting component. Electrochemical impedance spectroscopy (EIS) emerges as a potent diagnostic tool capable of pinpointing and disentangling the sources of resistance within an electrochemical device. Through deconvolution of different factors, EIS allows for the quantitative measurement of resistance evolution throughout full cell cycling, reflecting degradation through changes in resistance. Consequently, by monitoring resistance evolution with EIS, the degradation rates of individual factors can be calculated.
This study employs an alkaline aqueous organic redox flow battery with 2,5-di-tert-butyl-1,4-dihydroxybenzene sulfate (DHPS) as anolyte and ferrocyanide as catholyte for demonstration. EIS measurements are conducted at various cycles, and three distinct resistance components (charge transfer, ohmic, and mass transport) are identified as functions of cycle numbers. Subsequently, the degradation rates of crucial electrochemical parameters, such as reaction rate and mass transport coefficient, are quantified, providing essential inputs for subsequent modeling endeavors.