bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Single Cell Voltages for Safety, Predictive Maintenance, and Process Optimization of Industrial Scale Bipolar Electrolyzers (Learned Lessons From Over 30 Years Experience in Chlor-Alkali-Electrolysis)
Authors: Lademann Helmut , Tremblay Gilles , Simard Georges , Dubois Jacques , Berriah Said 
Published: September 2023

Just like the membrane electrolysis process in the Chlor-Alkali industry 30 years ago, water electrolysis is facing a major transformation from a niche technology to become a global commodity business. 30 years ago, the unique risks of big bipolar electrolyzers were not recognized by the industry. Lessons learned from incidents and near misses led R2 to the development of the EMOS® Safety System: the state-of-the-art single cell voltage-based safety instrumented system for bipolar electrolyzers. Today, the EMOS® Safety System has become a standard in the Chlor-Alkali industry. With plans announced for much larger electrolyzers and several times higher current densities and their increasing risks, water electrolysis should be spared this painful learning process. Fortunately, EMOS® Safety System supports also bipolar water electrolyzers. Short circuits, separator failures etc. can be only detected with single cell current-voltage-curves to turn the power supply off before explosive gas reaches areas with dangerous high gas holdup.
Same time the single cell voltages are used to detect any abnormal cell aging as early as possible and to correlate it with the operating conditions. For this purpose, automatically during the electrolyzer startup a neural network is trained to predict the cell voltages afterwards in real-time and to alarm already a deviation of a few mV from the measured cell voltage. Together with KPI’s like U0 and k, automatically calculated by analyzing load changes from normal electrolyzer operation for each cell, predictive maintenance, cell performance specific replacement and process optimization is possible, customized for the individual industrial plant.
Examples from industrial scale electrolyzers concerning safety, maintenance and performance optimization will be presented.
Mathematical Modeling of the Performance-Degradation Mechanisms of Cation-Contaminated Proton-Exchange-Membrane Water Electrolysis
Authors: Dizon Arthur , Padgett Elliot , Adesso Anthony , Wrubel Jacob A , Mukundan Rangachary , Pivovar Bryan S. , Alia Shaun M , Weber Adam Z. 
Published: September 2023

The role of hydrogen as a commercial energy carrier is dependent on the development of robust processes to convert hydrogen into usable electricity as well as produce hydrogen at large scales. Proton-exchange-membrane water electrolysis (PEMWE) is a leading technology with the potential to produce hydrogen at projected consumption rates. In PEMWE, water is electrochemically split into hydrogen and oxygen gas using a membrane—electrode assembly, which uses a membrane capable of transporting both water and protons. Reactant water containing cationic impurities have been observed to degrade cell performance. Thus, developing an understanding of the influence of cationic contaminants is important to developing mitigation and recovery strategies for PEMWE systems.
In the current work, mathematical models were developed to provide insight into the mechanisms of performance degradation due to cationic contaminants. The models are non-isothermal continuum models that describe multi-phase porous flow, electrochemical reactions, and concentrated-species transport in both the gas membrane, and ionomer phases. Simulations were performed in steady-state and transient operational modes for various cationic species at several ionic concentrations. The calibration and fitting of the models were performed using experimental measurements performed by the National Renewable Energy Laboratory. The mathematical models suggest that gradients facilitate the adsorption of cationic contaminants in reactant water, which subsequently accumulate in the cathode catalyst layer, as shown in Figure 1(a), and inhibit the PEMWE hydrogen-evolution reaction (HER) that consume protons and electrons to produce hydrogen gas. The models suggest that protonic conductivity is not significantly affected by low-concentration cationic species, but access to the catalyst active sites in the cathode catalyst layer is severely impeded. As a result, the evolution of hydrogen then proceeds by an alkaline mechanism, where water and electrons combine to produce hydrogen gas and hydroxide ions. An interpolated polarization curve shown in Figure 1(b) suggests that cell operation at high current densities favor the alkaline HER reaction due to the lack of protons in the cathode catalyst layer.
This research is supported by DOE Hydrogen and Fuel Cell Technologies Office, through the H2NEW Consortia.

Figure 1
A New Semi-Empirical Method of Quantifying Electrolyzer Degradation
Authors: Errico Shaina Brianne , Fortiner Serafina , Kulkarni Devashish , Motz Andrew R 
Published: September 2023

Electrolyzers are a key component in transitioning the world’s reliance on fossil fuels for energy. Accordingly, a substantial influence on electrolyzer costs is operational efficiency. The means of quantifying this efficiency is necessary for sustaining the continuous improvement of this technology.
Polarization curves are a critical tool in understanding the behavior and mechanisms of electrochemical devices such as electrolyzers and fuel cells. In this work, a semi-empirical voltage-breakdown method is used to model and identify a series of resistance levels and voltage losses. This model presents the modes of change in electrolyzer performance. Polarization curves are taken at several temperature and time intervals throughout steady state operation. The unique benefit of this method is that no potentiostat is required and that key parameters, such as the Tafel slope and ohmic resistance, are compared to more direct measurements.
Presented here, is a user-friendly technique of evaluating the degradation of an electrolyzer over the course of its lifetime. More specifically, it provides insight on the durability of cell components such as membrane, gas diffusion layers, and catalyst layers.
Iridium Nanosheet Catalysts Supported on Titanium Oxide for Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis
Authors: Shin Dongwon , Lee SangJae , Bak Junu , Roh JeongHan , Lee KwangHo , Chang HyunWoo , Cho EunAe 
Published: September 2023

In order to overcome the disadvantage of intermittent production of renewable energy, Polymer electrolyte membrane water electrolysis(PEMWE), which is one of the technologies of producing hydrogen by electrolyzing water, is attracting attention. For the commercialization of PEMWE, it is important to reduce usage of iridium(Ir) for oxygen evolution reaction(OER) in the anode electrode. Many studies have been reported to reduce the amount of iridium used by developing a catalyst with higher performance than the iridium nanoparticle catalyst used as a commercial catalyst. As one of the strategies, the introduction of support materials that can increase the active area of the catalyst is drawing attention. While carbon-based supports are mainly used in other applications, in OER environments, carbon is easily corroded due to high voltage and strong acid conditions. Therefore, it is necessary to use a metal oxide support with high corrosion resistance. In particular, titanium oxide(TiO2) is one of the suitable support candidates because it is a stable material in an acidic OER environment. However, catalysts loaded on TiO2 with nanoparticles cause an electrical contact problem due to the low electrical conductivity of TiO2, which causes a degradation in activity. Many studies have reported doping methods to increase the conductivity of TiO2, but there are also reports that these methods reduce the durability of support. Thus, a new approach to synthesizing a better structure of catalysts is needed to utilize metal oxide support.
Herein, we present an approach to iridium nanosheet (NS) catalysts supported on TiO2(Ir NS/TiO2). Ir NSs were synthesized by an facile method by directly annealing a mixture of Ir precursor and alkali salt. Ir NSs were supported on TiO2 to be utilized as a reaction site and also acts as an electron path to compensate for the low electrical conductivity of TiO2. Ir NS/TiO2 showed superior OER activity and stability under acidic conditions. These results showed that Ir NS/TiO2 could be utilized to reduce the amount of precious metal catalyst in PEMWE and increase the stability of OER supported catalysts.
Substitution of the Nafion® Ionomer with Hydroxypropyl Methylcellulose for Proton Exchange Membrane Water Electrolyzer
Authors: Cha Jeong In , Baik Chaekyung , Pak Chanho 
Published: September 2023

The use of green hydrogen as a clean energy carrier has become an essential method of storing renewable energy instead of fossil fuels because of environmental concerns[1,2]. Proton exchange membrane water electrolysis (PEMWE) is one of several methods of producing green hydrogen. A perfluorosulfonic acid ionomer called Nafion® was typically used as a binder in PEMWE for many years. It has excellent chemical stability and high ionic conductivity, but it is expensive and has negative environmental effects [3]. It is therefore necessary to investigate new binders for the anode of PEMWE.
In this study, we present a new electrode manufacturing method using hydroxypropyl methylcellulose (HPMC) binder and demonstrate that HPMC binder can be used sufficiently instead of traditional Nafion® ionomer through single-cell evaluation under PEMWE conditions. Although it has the disadvantage of low proton conductivity, HPMC is cost-effective and eco-friendly. In the case of the PEMWE anode, because water moves into the cell, water can take over the role of hydrogen ion transport instead of the HPMC binder. By the electrode’s interfacial stability test, it was discovered that the HPMC electrode’s form was preserved for 24 hours without any peeling. Further, it can be seen that there is no significant difference in PEMWE performance even if an HPMC binder with relatively low ionic conductivity is used. Additionally, it was established that each electrode demonstrated a low degradation (less than 0.3 mV h-1) in the subsequent 72 h durability test. The proposed affordable new binder HPMC can aid the development of a new electrode and a cost-effective PEMWE system.

References

[1] Y. Li, Y. Sun, Y. Qin, W. Zhang, L. Wang, M. Luo, H. Yang, and S. Guo, Adv. Energy Mater., 2020, 10, 1-20.
[2] Z. Chen, X. Duan, W. Wei, S. Wang, and B. J. Ni, J. Mater. Chem. A., 2019, 7, 14971-15005.
[3] E. Oakton, D. Lebedev, M. Povia, D.F. Abbott, E. Fabbri, A. Fedorov, M. Nachtegaal, C. Copéret, T.J. Schmidt, ACS Catal., 2017, 7, 2346-2352.
[3] Klose, C., Saatkamp, T., Münchinger, A., Bohn, L., Titvinidze, G., Breitwieser, M., Kreuer, K.D., and Vierrath, S., Adv. Energy Mater. 2020, 10, 1903995.
IrxNb1-XO2 Mixed Metal Oxides As Anode Catalyst for PEM Electrolysis: From Fundamentals to Application
Authors: Kroschel Matthias , Strasser Peter 
Published: September 2023

Summary. Here we describe the synthesis of IrxNb1-xO2 (mixed) metal oxides powders with several compositions. The catalysts are characterized with a variety of techniques to achieve a structure – activity relation. Furthermore, the effect of annealing temperature is addressed. Promising catalysts were tested in a full electrolysis cell as well.

Abstract. Electrochemical water splitting will play a crucial role in future industries and will contribute to a more sustainable economy. Hydrogen produced by electrolysis is suitable to replace hydrogen produced by fossil fuels, enables the electrification of multiple sectors and can be used as long- and short-term chemical energy storage system [1].
Here we describe the synthesis of IrxNb1-xO2 (mixed) metal oxides powders. Several compositions regarding the Ir/Nb ration are synthesized and studied. The study is based on previous experimental and theoretical findings using model films of IrxNb1-xO2 [2]. We address fundamental properties like crystal structure and composition and furthermore, test the catalysts in full electrolysis cell measurements. The synthesized materials are analysed using a variety of techniques, like XRF, XRD, RDE, BET, SEM, TEM, TGA and conductivity measurements to determine the activity and stability, crystal structure, morphology and conductivity. Furthermore, the effect of the annealing temperature on the above mentioned properties was studied. The optimal composition was determined based on activity and stability measurements in a three-electrode setup and physical properties like the powder conductivity.
The synthesized catalysts could outperform commercial catalysts in terms of activity and stability and can be used with lower Ir loadings. XRD measurements reveals an IrO2 rutile structure with very broad peaks, indicating an amorphous crystal structure.
The most promising catalysts were evaluated in a full electrolysis cell with different loadings.
[1] Getting Hydrogen to the Gigaton Scale; B. S. Pivovar, M. F. Ruth, A. Nakano, H. Furutani, C. Hebling, T. Smolinka; Electrochem. Soc. Interface. 2021, 30, 85.
[2] Molecular Analysis of the Unusual Stability of an IrNbOx Catalyst for the Electrochemical Water Oxidation to Molecular Oxygen (OER); C. Spöri, L. J. Falling, M. Kroschel, C. Brand, A. Bonakdarpour, S. Kuhl, D. Berger, M. Gliech, T. E. Jones, D. P. Wilkinson, P. Strasser
(Invited) Electrochemical Construction of 3-D Catalyst Layer on Ordered Liquid-Gas Diffusion Electrode for Highly Stable and Cost-Efficient PEM Water Electrolyser
Authors: Yan Changfeng , Ding Chao , Lu Zhuo-xin , Shi Yan 
Published: September 2023

Proton exchange membrane (PEM) water electrolyser is an ideal way to produce green hydrogen with intermittent renewable energy. The high cost of noble metal in membrane electrode assembly is one of the key problems to be solved for its commercial applications. Developing 3-D electrode with high utilization of noble metal and prominent performance of mass diffusion is a promising solution.
In this work, titanium foil with ordered openings is applied as liquid-gas diffusion layer (LGDL) for anode by photolithography. And 3-Dimensional structural catalyst layer (CL) is coated by controlled pulse electrodeposition. By adjusting the concentration of electrolyte, current density and pulse parameter, catalyst layer with structure of nanowires, nano-urchin and nano-flower can be obtained. With medium current density of 5 mA/cm2, a structure variation from nanowire to nano-urchin could be observed by prolonging the electrodepositing time. While high current density of 20 mA/cm2 was applied, catalyst layer with nano-flower structure was formed. However, similar morphology could not be observed when a flat titanium foil was used as substrate. The controlling mechanism would be studied with scanning electrochemical microscopy to unveil the key controlling issue, such as distribution of local current and steric effect of released gas.
The single cell performance with nano-urchin CL coated ordered LGDL as anode electrode was studied. Though coverage of anode electrocatalyst on PEM is only 45% as the porosity of order LGDL is 55%, the single cell performs excellent activity and stability due to the high surface area, enhanced mass diffusion and structural stability of 3-D CL. With optimized loading of 0.25 mgIr /cm2, initial performance of 1.795 V@ 1 A/cm2 can be obtained. And a prominent performance on stability with decay rate of 4.17 μV/h is shown after 4000h running under 1A/cm2 at 80 ℃. It is predictable that, by further adjusting the pore diameter and porosity of order LGDL to optimize the area of electrocatalyst/membrane interface and mass diffusion, the performance could be further improved to fulfill long-term operation under high current density (＞2A/cm2).

Figure 1
Structural Transformations in Ni (Oxy)Hydroxide Host Structures Under Operating Conditions for Oxygen Evolution Electrocatalysts
Authors: Dionigi Fabio , Zeng Zhenhua , Zhu Jing , Merzdorf Thomas , Klingenhof Malte , Buchheister Paul Wolfgang , Li Wei-Xue , Greeley Jeffrey , Strasser Peter 
Published: September 2023

The incorporation of Fe into the brucite-like Ni(OH)2 host structure increases significantly the catalytic activity for the oxygen evolution reaction (OER).1 The resulting hydrotalcite-like crystalline structure is known as NiFe layered double hydroxide (LDH). However, even the most active NiFe LDH catalyst still shows a considerable overpotential for the OER.2 Understanding the nature of the catalytic active sites and the catalytic mechanism in NiFe LDHs are key challenges to develop better OER electrocatalysts, as well as the fundamental understanding of the role of the Ni-based host structure.
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-phases to activated γ-phases.3 The interlayer and in-plane lattice parameters of the OER-active γ-phase were obtained by performing wide angle X-ray scattering (WAXS) measurements on NiFe LDH nanoplatelets during operating electrochemical conditions and were characterized by a contraction of about 8%. Operando WAXS was then performed for other selected catalysts belonging to the transition metal LDH family of materials. Structural similarities of the catalytically active phases will be highlighted. In addition, the structural transformations of β-Ni(OH)2 will be discussed, as potential host structure for novel multi-element catalysts. Also for Ni(OH)2, the γ-phase is found to be the catalytically active phase. However, the structural transformations are more complex, involving multiple limiting phases. Their structural stability is presented and the discussion supported by density functional theory calculations.

References

L. Trotochaud, S. L. Young, J. K. Ranney and S. W. Boettcher, Journal of the American Chemical Society, 2014, 136: 6744-6753.

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

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, 2020, 11 2522.
Nife LDH: From Molecular Understanding to Highly Active Single Cell Measurements
Authors: Klingenhof Malte , Trzesniowski Hanna , Metzler Lukas , Koch Susanne , Dionigi Fabio , Vierrath Severin , Strasser Peter 
Published: September 2023

NiFe layered double hydroxide (LDH) is among the most active oxygen evolution reaction catalysts in an alkaline environment. Still, scaling the synthesis of NiFe LDH to application related multi gram scale is yet not fully investigated. This is accompanied with missing understanding of the nature of the catalytic active sites. Furthermore, fully convincing measurements of NiFe LDH in single cell environment with PEM-like activities are not reported up to date.
In this contribution, the detailed successful scaling of the NiFe LDH synthesis to multi-gram scale will be presented. Furthermore atomic-scale investigations of the catalytic active phase revealed by in-situ X-Ray measurements will be presented, showing that oxygen features visible in the oxygen K-edge are contributor to the excellent OER activity of NiFe LDH. Time-resolved measurements of the Ni L-edge show that the formation of the specific oxygen feature is directly accompanied with Ni oxidation. These oxygen features are also found in IrOx catalysts under applied oxygen evolution reaction relevant conditions.1,2 Finally, NiFe LDH was used to prepare membrane-electrode assemblies (MEA) with a previously reported advanced method.3 The resulting MEAs provided PEM-like activities (approx. 2.3 A cm-2 at 1.8 V, 1 M KOH, 80°C) in a single-cell AEMWE setup. Thus, the herein presented work provides successful insights into catalyst synthesis development, in-situ investigations of catalytic active sites as well as implementation of the investigated catalyst into application related full cell measurements.
References
1 Nong, H. N. et al. Key role of chemistry versus bias in electrocatalytic oxygen evolution. Nature
587, 408-413, doi:10.1038/s41586-020-2908-2 (2020).
2 Nong, H. N. et al. The Role of Surface Hydroxylation, Lattice Vacancies and Bond Covalency in the Electrochemical Oxidation of Water (OER) on Ni-Depleted Iridium Oxide Catalysts. Zeitschrift für Physikalische Chemie
234, 787-812, doi:10.1515/zpch-2019-1460 (2020).
3 Koch, S. et al. Toward Scalable Production: Catalyst‐Coated Membranes (CCMs) for Anion‐Exchange Membrane Water Electrolysis via Direct Bar Coating. Advanced Sustainable Systems, doi:10.1002/adsu.202200332 (2022).
Anodized Stainless Steel 316 and 304 Alloys As Bifunctional Water Splitting Electrocatalytic Materials in Alkaline Media
Authors: Heiba Asmaa R. , Abd El-hamid Shimaa , El Sawy Ehab 
Published: September 2023

The world is facing a continued increase in population that is accompanied by a high demand for energy. The dependence on fossil fuels caused demand and environmental crises. Therefore, it is necessary to switch to sustainable, clean, and renewable sources of energy immediately. Using hydrogen as a fuel is considered the most cleanest and promising alternative. Producing hydrogen using water electrolysis is the most environmentally friendly and sustainable method, especially when the electricity is generated from renewable sources. Employing electrolysis for hydrogen production is currently limited due to its high cost and low efficiency. For improving the efficiency of the electrolyzers and significantly decreasing the cost, it is necessary to increase the rate of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by designing more active, stable, easy-to-fabricate electrocatalysts that are bifunctional and could be commonly fabricated for both the HER and OER.
The different stainless steel (SS) alloys are common and inexpensive Fe-Ni-based alloys that recently attracted attention not only as conductive substrates for HER and OER catalysts but as electrocatalysts themselves.1 Untreated SS is poorly active towards HER or OER and needs further modification, such as electrochemical anodization followed by high-temperature annealing in different gases, to reach an acceptable activity.2,3 Anodized SS annealed under O2 is shown to be catalytically active towards OER while annealing under H2 is required for HER activity.2,3

Herein, the effect of anodizing the SS316 and SS304 alloys at different potentials and bath compositions (H2O, NH4F, H2SO4, and H3PO4 contents) on the electrode morphology and surface composition will be discussed. The anodized SS electrodes are annealed in different thermal annealing atmospheres (O2, and H2) and annealing temperatures (400-800 Cº). The physical/chemical structure of as received SS (R-SS), the annealed SS (A-SS), the anodized SS (AN-SS), and the anodized-annealed SS (A-AN-SS) electrodes were evaluated using XRD, FESEM, EDS, and XPS. The electrocatalytic behavior of the SS electrodes towards HER and OER in Alkaline solutions is evaluated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS). The results will be discussed thoroughly to correlate the electrochemical behavior to the electrode morphology and surface composition.

References:

S. Anantharaj et al., ACS Sustainable Chem. Eng., 6, 2498–2509 (2018).

A. K. Gomaa, B. S. Shaheen, G. E. Khedr, A. M. Mokhtar, and N. K. Allam, Energy Fuels, 36, 7025–7034 (2022).

M. Kim, J. Ha, N. Shin, Y.-T. Kim, and J. Choi, Electrochimica Acta, 364, 137315 (2020).