bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bridging the Gap between Laboratory and Industrial Scale Electrochemical Characterisation of Raney Ni Electrodes for Alkaline Water Electrolysis
Authors: Prits Alise-Valentine , Maide Martin , Väli Ronald , Tammemägi Mona , Nguyen Huy Quí Vinh , Küngas Rainer , Nerut Jaak 
Published: August 2024

The most mature water electrolysis technology is alkaline electrolysis, where an aqueous solution of KOH is used as the electrolyte. While this technology has been used for decades, there is still a lot of potential to improve the performance of these devices. Much research is focused on the optimisation of the electrodes containing novel catalyst materials that lower the activation energy barrier of the electrolysis process. However, one of the issues described by Ehlers et al.1 is that the current academic electrolysis research is done under conditions that are far from practical (e.g. at low current densities, room temperature, and dilute electrolytes).
In this study, we characterise a commercial Raney nickel electrode in various setups using a systematic series of experiments, including a typical laboratory-scale three-electrode setup, two different flow-cell setups and a 10-kW electrolysis stack of 17 cells. In addition to the cell geometry (electrode area ranging from 1 cm2 to 960 cm2), the varied measurement conditions include temperature (ranging from room temperature to 80 degrees Celsius), pressure (from atmospheric pressure to ), electrolyte concentration (from 0.1 M to 30 wt% KOH), and the level of Fe impurities in the electrolyte. The resulting electrochemical data received from different measurement setups and measurement conditions are compared, and insights about the challenges related to correlating laboratory experiments to industrial-scale experiments are provided.

Figure 1. Alkaline electrolysis measurement setups with the typical measurement conditions used to study Raney nickel electrodes within this work – a typical laboratory-scale three-electrode setup (a), two different flow-cell setups (b, c) and a 10-kW electrolysis stack of 17 cells (d).

Acknowledgements

This work was supported by the Applied Research Program of Enterprise Estonia ("Developing and Validating Alkaline Electrolysis Stack Technology with Nanoceramic Electrodes", RE.5.04.22-0109) and by the Estonian Research Council (EAG273 "Highly active electrodes for precious metal free alkaline electrolysers" (1.09.2023−31.08.2024)).

References

J. C. Ehlers, A. A. Feidenhans’l, K. T. Therkildsen, and G. O. Larrazábal, ACS Energy Lett., 8, 1502–1509 (2023).

Figure 1
Intrinsic Activity and Ni-O-Fe Catalytic Active Site in Ni-Based (Oxy)Hydroxides for the Oxygen Evolution Reaction
Authors: Dionigi Fabio , Zeng Zhenhua , Zhu Jing , Merzdorf Thomas , Choi Donggyu , Ligay Darya , Klingenhof Malte , Buchheister Paul Wolfgang , Li Wei-Xue , Greeley Jeffrey , Strasser Peter 
Published: August 2024

NiFe layered double hydroxides (LDHs) and (oxy)hydroxides are among the most active electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes.1 However, they still show considerable overpotentials for the OER, i.e. 350 mV at 10 mA cm-2 in pH 13.1, 2 Understanding the nature of the catalytic active sites and the catalytic mechanism in NiFe LDHs are key challenges to develop better OER electrocatalysts.
In this contribution, atomic-scale details of the catalytic active phase will be presented, showing that NiFe LDHs are oxidized under applied anodic potentials from as-prepared α-phase to activated γ-phase.2 The OER active γ-phase was characterized by operando wide angle X-ray scattering (WAXS) in alkaline electrolytes.2 The intrinsic activity was then obtained by an electrochemical impedance method through electrochemical surface area (ECSA) normalization.3 Comparison with other Ni- and Co- based LDHs revealed that NiFe LDH shows the highest intrinsic activity.4 Our density functional theory (DFT) calculations on a γ-phase atomic model showed that O-bridged Ni-Fe reaction centers (Ni-O-Fe) stabilize OER intermediates that are unfavourable on Ni-O-Ni centers and single Fe sites, fundamentally accounting for the high catalytic activity. Furthermore, our DFT calculations predicts that γ-NiFe LDH is close to, but not on, the top of the OER volcano.2,4 Strategies to modify the catalytic active site to approach the top of the volcano will be presented, together with preliminary experimental results. These strategies will involve the design of active sites involving subsurface metal sites and electronic modulation of the Ni-O-Fe sites by introduction of a third transition metal element.

References

F. Dionigi and P. Strasser, Advanced Energy Materials, 6, 1600621 (2016).

F. Dionigi, Z. Zeng, I. Sinev, T. Merzdorf, S. Deshpande, M. B. Lopez, S. Kunze, I. Zegkinoglou, H. Sarodnik, D. Fan, A. Bergmann, J. Drnec, J. Ferreira de Araujo, M. Gliech, D. Teschner, J. Zhu, W.-X. Li, J. Greeley, B. Roldan Cuenya and P. Strasser, Nat. Commun., 11, 2522 (2020).

S.S. Jeon, P.W. Kang, M. Klingenhof, H. Lee, F. Dionigi, P. Strasser, ACS Catal., 13, 1186-1196 (2023).

F. Dionigi, J. Zhu, Z. Zeng, T. Merzdorf, H. Sarodnik, M. Gliech, L. Pan, W.-X. Li, J. Greeley, and P. Strasser, Angew. Chemie IE, 60, 14446 – 14457 (2021)
Accelerated Discovery of Multi-Metallic Nanostructured Catalysts for Anion Exchange Membrane Water Electrolyzers: Oxygen Evolution Reaction
Authors: Farghaly Ahmed A. , Onajah Sammy , Lalley Marja , Kreider Melissa E , Alia Shaun M , Yu Haoran , Myers Deborah J. 
Published: August 2024

The current reliance on platinum group metals (PGMs) as electrocatalysts for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) water electrolyzers, the current industry standard, presents a significant barrier to the widespread adoption of hydrogen as a clean energy carrier. The scarcity and high cost of PGMs necessitate the development of alternative materials and technologies that offer comparable performance at a reduced cost. In this context, anion exchange membrane (AEM) water electrolyzers have emerged as a promising alternative.
This presentation addresses this imperative by focusing on the design and synthesis of nanostructured mesoporous multi-metallic catalysts for AEM water electrolyzers, leveraging earth-abundant materials as alternatives to the rare and expensive PGMs currently employed in PEM water electrolyzers. Transition metal oxides, sulfides, and phosphides are promising candidates to replace PGMs, given their abundance, low cost, and tunable catalytic properties conducive to high OER activity. The OER activity and durability of newly developed multi-metallic transition metal catalysts in an alkaline environment will be discussed in this presentation.
Preliminary results demonstrate that the developed catalysts exhibit high OER activity, achieving a potential of <1.5 V versus RHE at a current density of 10 mA cm⁻² in 1.0 M KOH. Notably, this surpasses the performance of commercial OER catalysts in alkaline environments. Furthermore, the catalyst exhibits superior durability, with < 0.5 mV/h potential loss over 100 h durability test at 10 mA cm⁻² in 1.0 M KOH.
Acknowledgments
This work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). Argonne is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, under Contract DE-AC-02-06CH11357
.
Effect of Catalyst and Electrode Structures on the Operating Current Densities of Liquid Alkaline Water Electrolyzers
Authors: Maurya Sandip , Leonard Daniel , Chhetri Manjeet 
Published: August 2024

Liquid Alkaline Water Electrolyzers (LAWEs) stand out as the technology best-suited for cost-effective hydrogen production. They do not require expensive platinum group metal catalysts and have proven durability afforded by nickel-based electrodes and porous separators. While nickel electrodes and porous separators provide chemical stability in highly alkaline conditions, they do suffer from lower catalytic activity for hydrogen and oxygen evolution reactions (HER and OER), and separators possess higher ohmic resistance due to the absence of ion-conducting groups. Consequently, most LAWEs operate at low current densities ranging from 0.2 to 0.6 A/cm2, resulting in a bulky footprint and comparatively lower energy efficiency due to a reduced hydrogen production rate. To address these challenges, considerable efforts have been directed towards developing thin separators and efficient transition metal-based electrocatalysts for HER and OER in alkaline media. However, the majority of studies related to catalysts are limited to half cells, with only a limited number of catalysts evaluated in relevant LAWE configurations.
In this work, we introduce a next-generation Zero-gap LAWE testing capability, benchmarked for performance through H2NEW consortia. Employing this setup, we have evaluated hydrogen and oxygen evolution catalysts under LAWE-relevant conditions on different electrode substrates, each offering a unique electrode structure. Our preliminary findings indicate that Zero-gap LAWEs, when coupled with NiMo cathode and NiFe-type anode catalysts, can operate at current densities exceeding 0.75 A/cm2 at approximately 1.8 V without compromising their short-term durability. In contrast, the benchmark cell exhibited a meager current density of around 0.22 A/cm2. In this presentation, effects of electrode structure, catalyst type, and other relevant parameters related to Zero-gap LAWEs will be discussed in detail.

Acknowledgement:
This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium.
Understanding the Impact of Conditioning Protocols for Water Electrolyzers on Durability
Authors: Diaz-Abad Sergio , Yu Haoran , Park Jaehyung , Kariuki Nancy N. , Cullen David A. , Myers Deborah J. , Spendelow Jacob S. , Komini Babu Siddharth 
Published: August 2024

The global push towards climate neutrality has intensified research efforts on green hydrogen production technologies. Among them, proton exchange water electrolysis (PEMWE) stands out as a highly efficient technology for producing green hydrogen using renewable energies. Nevertheless, a significant reduction in the cost of PEMWE while maintaining its durability over its operational periods is imperative. The DOE’s Hydrogen Earthshot target aims to achieve $1 per 1kg of H2 production within the decade. Reducing the amount of expensive iridium catalysts also reduces the durability of PEMWE. Hence, understanding the degradation mechanisms of low Ir loading PEMWE holds utmost importance. One key step in the evaluation of PEMWE is the break-in or conditioning step. Ensuring optimal conditioning is crucial to guarantee the peak performance of membrane electrode assembly (MEA) before assessing the durability of the catalyst thereby ensuring representative and reproducible results.
This research aims to comprehensively evaluate various conditioning protocols for PEMWE and their impact on durability. Utilizing a combination of electrochemical, electron, and X-ray characterization techniques. Accelerated stress tests (AST) will be conducted after each conditioning protocol to evaluate the degradation rate of the catalyst. Ex-situ characterization of the MEA post-conditioning as well as post-AST offers a comprehensive understanding of how the catalyst’s initial state, such as the iridium oxidation state, following the conditioning step directly influences the durability. The goal is to develop an optimal conditioning protocol for PEMWE, that considers the performance and durability challenges associated with low catalyst loading.

Acknowledgment

This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium with support from Dave Peterson and McKenzie Hubert.
Syntheses of Ni-Based Layered-Double Hydroxide Materials Via Liquid Phase Deposition Method for Alkaline Water Electrolysis
Authors: Minamimoto Hiro , Okayama Tatsuya , Mizuhata Minoru 
Published: August 2024

For the sustainable society, hydrogen production has received much attention during decades. The alkaline water electrolysis process has been recognized as one of the important processes for hydrogen products. For the achievements of an effective water electrolysis system, the decrease of the overpotential on the oxygen evolution reaction (OER), which is the four-electron and proton transfer process. These complex 4-electron sluggish processes lead to the large energy losses in the whole water electrolysis. Although the noble catalysts such as IrO2 or RuO2 exhibit high OER activity, their large-scale applications are limited due to cost problem. From this point of view, the low-cost transition metal materials, especially Ni-based catalysts, have been extensively studied. And also, it has been reported that the well-defined layered double hydroxide (LDH) structures can promote water oxidation through the interlayer anion effects. Despite this fact, the specific procedures for the preparation of Ni-based LDH structures have not been well established. Therefore, in this study, we have investigated the preparation of Ni-based LDH structures in the aqueous solution at room temperature, the so-called liquid phased deposition (LPD) method.
Through the LPD method, we have synthesized various types of Ni-based LDH structures. As an example, the Ni-Al LDH structures were synthesized on the conductive substrate. It was found that our synthesized Ni-Al LDH exhibited relatively high OER activity and durability against electrochemical potential cycling [1]. In addition, the dependencies of the OER activity on the interlayer anion species were clearly demonstrated. In addition, the other types of Ni alloy LDHs were also prepared and their OER activity was investigated. Through the electrochemical measurements, we have confirmed the advantages of our materials prepared by LPD methods as an anode for alkaline water electrolysis.
References
[1] H. Minamimoto et al., Electrochemistry, 2023, 91(6), 067005.
How the Quasi-Eqilibrium Condition Has Obfuscated Electrochemistry in General and the HOR/HER Discussion in Particual (Part 1)
Authors: Chatzichristodoulou Christodoulos , Brandes Benedikt Axel 
Published: August 2024

Most reactions in electrocatalysis involve the transfer of multiple electrons. Due to the unlikely transfer of more than one electron at once, such reactions are multistep reactions. However, electrochemical textbooks focus heavily on the one-electron one-step reaction and there seem to be no consensus in the literature on how to treat multistep reactions.
We will elucidate how multistep reactions can be treated in a straightforward manner. In this process we explain that the Tafel slope, despite common practice and a recent IUPAC report, cannot be used to determine the reaction mechanism. This misconception stems from the inappropriate use of the quasi-equilibrium condition in the electrochemical literature.
We continue to show that the concept of the exchange current density cannot be universally defined for multistep reactions and that it is in almost no cases possible to accurately fit a multistep reaction by a simple Butler-Volmer equation.
Finally, we present how the HOR/HER reaction mechanism on Pt can be identified when the Butler-Volmer model is rigorously applied on the two HOR/HER paths dominating the discussion, namely the Tafel-Volmer and Heyrovský-Volmer.

Figure 1
Water Splitting and Beyond
Authors: Menezes Prashanth W. 
Published: August 2024

Hydrogen (H2) is a clean and environmentally friendly fuel, showcasing significant potential as a viable substitute for traditional fossil energy sources. Electrolysis, particularly the electrolytic splitting of water, emerges as one of the most environmentally benign methods for producing H2.1 Recent advancements have witnessed the emergence of cost-effective and durable catalysts, predominantly leveraging transition metals, demonstrating remarkable efficiency for water splitting Our ongoing research endeavors aim to push the boundaries further by exploring unconventional (non-oxide) catalysts based on non-noble metals. The objective is to identify catalysts that exhibit superior overall catalytic efficiency by a comprehensive investigation into the structural transformations, active sites, surface, and bulk structures under dynamic conditions. Additionally, we are delving into the influence of precatalysts on the properties of the final catalyst, striving for a holistic understanding to optimize the catalytic process.
Water splitting is hindered by the anodic oxygen evolution reaction (OER), a process entailing four-electron transfer and numerous high-energy reaction intermediates.2 Partly, electrochemical organic oxidation reactions (OOR) can effectively supersede the sluggish OER (hybrid-water electrolysis), and accelerate the overall hydrogen production rate.3 This also significantly enhances the techno-economic viability of water-splitting as selective high-valued organic oxidation products are formed at the anode, as opposed to the less valuable oxygen.4 This talk will shed light on the recent developments of selected catalysts for electrocatalytic OER and OOR and will discuss the dynamic state of the catalysts via comprehensive in-situ and ex-situ techniques.5 The ultimate goal is to pave the way toward a concept-guided design system that extends beyond conventional water electrolysis.

References

[1] Chen Z.; Yang H.; Kang Z.; Driess M.; Menezes, P. W., Adv. Mater. 2022, 2108432.
[2] Hausmann J. N.; Menezes P. W., Angew. Chem. 2022, 134, e202207279.
[3] Yang H.; Vijaykumar G.; Chen Z.; Hausmann J. N.; Mondal I.; Ghosh S.; Nicolaus C. J. V.; Laun K.; Zebger I.; Driess M; Menezes P. W., Adv. Funct. Mater. 2023, 2303702.
[4] Kahlstorf T.; Hausmann J. N.; Sontheimer T.; Menezes P. W., Global Challenges 2023, 7, 2200242.
[5] Reith L.; Hausmann J. N.; Mebs S.; Mondal I.; Dau H.; Driess M.; Menezes P. W., Adv. Energy Mater. 2023, 13, 2203886.
Electrocatalysis for Water Splitting Using Layered Zirconium Phosphate Nanomaterials
Authors: Colon Jorge L , Serrano-Rosario Yannelly A. , Muñoz-Torres Sebastián , Gibson Colón Daniella , Liu Biao , García-Machado Gabriela , Defebve Louise M. , Pollock Christopher 
Published: August 2024

We are studying new applications of layered zirconium phosphate (ZrP) inorganic nanomaterials [1]. The θ phase of ZrP can be directly ion-exchanged with metal complexes and catalysts, producing intercalated phases useful for artificial photosynthesis schemes for water splitting, amperometric biosensors, and drug delivery applications. Recently, we have demonstrated improved electrocatalytic activity of ZrP nanomaterials loaded with metal ions suitable for the oxygen evolution reaction of water splitting. Electrocatalysts have been incorporated as intercalated species, surface bound, on exfoliated layers, and on nanoparticles of different morphologies (hexagonal platelets, cubes, rods, and spheres). Single and bimetallic electrocatalysts based on earth-abundant materials have been studied. Reduction in overpotentials and increases in mass activity have been achieved. Mixed metal NiFe-intercalated ZrP electrocatalysts at 90% Fe metal content proved to have superior OER electrocatalytic performance (decreased overpotentials, increased mass activities, reduced Tafel slopes) compared to adsorbed counterparts. We have recently prepared CoFe electrocatalysts systems and again the intercalated bimetallic system is more active than the surface-adsorbed one. We are starting to work also with Mn electrocatalysts. We are exploring OER activities of other mixed-metal catalysts on ZrP, bifunctional catalysts, and operando synchrotron X-ray absorption spectroscopy studies to elucidate the nature of the active species. We are also exploring efficient solar H2 production using these supports.
Reference
[1] M. V. Ramos-Garcés; J. González-Villegas; A. López-Cubero; J. L. Colón, Acc.
Mater. Res.
2021, 2, 793-803. DOI: 10.1021/accountsmr.1c00102.
Microstructural Characterization of Porous Transport Layer Coatings
Authors: Arregui-Mena David , Grejtak Tomas , Domingo Marimon Neus , Stelmacovich Genevieve , Pylypenko Svitlana , Liu Chang , Bender Guido , Cullen David A. 
Published: August 2024

The porous transport layer (PTL) is a key component in polymer electrolyte membrane (PEM) water electrolyzers and serves the role of controlling the transport of reactants and products to and from the anode. Maintaining a low interfacial contact resistance between the titanium (Ti) fiber or sinter PTL and the iridium (Ir) anode catalyst is critical to maintaining the performance of the electrolyzer cell. This requires costly precious metal coatings, typically Pt, to inhibit the formation of native oxide layers during long-term cell operation. Strategies to reducing the thickness of these costly coatings including surface treatments, such as etching and abrasion, alternative low-cost coating materials, and implementation of microporous layers. It is crucial to understanding the morphologies and degradation mechanisms of these new strategies in order to accelerate the development of cheaper, more robust PTL coatings.
In this work, correlative ex situ characterization methods, including laser confocal microscopy (LCM), focused ion beam (FIB), scanning electron microscopy (SEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM), are utilized to explore the impact surface treatments, such as etching and abrasion, on the Pt coatings uniformity and surface roughness. The thickness, local topography, and continuity of the Pt coating were quantified and correlated with interfacial contact resistance and electrochemical cell performance measurements. Changes to the thickness and composition of the coatings and oxide layers after single-cell tests will also be reported. Overall, these findings aim to guide the development of PTL treatments and coatings, ensuring the creation of highly durable and efficient PEM water electrolyzers that align with the U.S. Department of Energy's Hydrogen Shot goal of reducing the cost of clean hydrogen production to $1 per kilogram by 2031.
Funding for this work was provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the H2NEW Consortium. Electron microscopy research conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.