Toward sustainable hydrogen production: Insights into membrane electrode assembly durability and degradations in proton exchange membrane water Electrolyzers

Sustainable hydrogen (H2) production via water electrolysis is one of the most critical pathways to decarbonize the chemical industry. Among various electrolyzer technologies, proton exchange membrane (PEM) water electrolyzer (PEMWE) is widely regarded as having a great advantage and promise for large-scale H2 production given its high efficiency, reliable stability, and high output pressure. Though state-of-the-art iridium-based catalysts exhibit satisfying activity and stability for oxygen evolution reaction at the anode, their high loadings, as well as the precious metal coating and titanium bulk of porous transport layer (PTL) and bipolar plates, significantly add to the capital cost of the PEMWE stack. The respective optimization and integration of PTL, catalyst layer (CL) and PEM is critical for enhancing charge transfer, mass transport, and catalyst utilization to lower the operation and capital cost, yet it has not received adequate attention. In this review, anode engineering strategies to rationally design PTL, PTL/CL interface and PEM/CL interface for performance improvement and cost reduction are summarized. Current understandings on PTL material, structure, and two-phase transport properties are first gathered, followed by the discussion of anode interface engineering methods and catalyst coating techniques. Given the raising attention to large-scale water electrolyzers operating at high current densities, this review provides a practical and comprehensive direction for next-generation PEMWE anode design by addressing the integration of key components related to the cost, efficiency and stability issues in PEMWE.

Proton exchange membrane (PEM) water electrolyzers represent a cornerstone technology in the sustainable production of green hydrogen. However, their large-scale commercialization is hindered by catalyst degradation, particularly the iridium-based anode, which compromises the efficiency and durability of the stack. This study delves into the degradation mechanism(s) of the Ir-based catalyst in the anode of PEM electrolyzers, focusing on the influence of operating conditions such as current density and cell voltage. We have utilized the state-of-the-art R&D platform “PEMI” at Plug Power to construct a rainbow stack that contains several 50 cm2 membrane electrode assemblies (MEAs) with different membrane thicknesses. This innovative approach enables identical current densities across different MEAs while varying the cell voltage on the anode catalyst layer, thereby isolating the effect of cell voltage from current on catalyst degradation.Our investigation seeks to clarify the puzzle whether it is the current density or the cell voltage that determines the transition and degradation of iridium-based catalysts. Preliminary results indicate that different oxidation states of Iridium exhibit significantly different kinetics and conductivity at varied cell voltages. This is corroborated by our synchrotron-based in situ X-ray absorption spectroscopy experiments that unraveled evolution of the anode catalyst layer at elevated cell voltages. By systematically analyzing the degradation patterns of MEAs with different membrane thickness under controlled conditions, we pinpointed the operational parameter that drives catalyst degradation. The finding provides in-depth understanding of the underlying principles that govern the iridium-based catalyst durability and points to strategies mitigating the degradation. It will pave the way for more resilient and efficient PEM water electrolyzers. Acknowledgement. This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory Contract DE-SC0012704. Beamline operations were supported in part by the Synchrotron Catalysis Consortium Grant DE-SC0012335.Keywords: PEM water electrolyzers, catalyst degradation, iridium, current density, cell voltage, MEAs.

Water electrolyzers and fuel cells can be used to create a closed loop system for space exploration. Electrolyzers allow for reliable self-sustainable generation of hydrogen and oxygen for energy storage, followed by conversion into electrical energy in a fuel cell. A first-order safety concern for water electrolyzer operation is hydrogen crossover. Transport of hydrogen to the oxygen rich anode in proton exchange membrane (PEM) water electrolyzers poses safety concerns when the hydrogen concentration in the anode flow field approaches the hydrogen lower flammability limit (LFL). Hydrogen storage efficiency relies on high hydrogen pressure, leading to pressure-driven hydrogen crossover. Mitigation of hydrogen crossover through research and development of a platinum metal recombination layer has been demonstrated in high performing, durable PEMWEs.1-4 Ouimet4 explored the use of a novel dual recombination layer configuration to mitigate PEM water electrolyzer hydrogen crossover. In addition, the current state of the art for PEM fuel cells and water electrolyzers rely on perfluoro-sulfonated acid (PSFA) based membranes. There are significant challenges facing the use of PSFA-based membranes; namely, environmental contamination and performance limitations. The use of a hydrocarbon membrane allows for the development of a PSFA-free system that shows higher efficiency and durability. Investigation of hydrocarbon membranes pave way for developing a PEM water electrolyzer that will demonstrate improved gas permeability resistance, mechanical strength, and thermal stability.5-8 There is a need for both hydrogen crossover mitigation strategies and durability testing with hydrocarbon membranes.The research outlined in this work is focused on the development of PSFA-free PEM water electrolyzers with low hydrogen crossover. In this work, the dual recombination layer configuration will be incorporated into a hydrocarbon membrane for PEM water electrolysis. Polarization, electrochemical impedance spectroscopy, electrochemical equivalent circuits, distribution of relaxation times, and materials characterization will be used to investigate the cell performance and durability. References G. Mirshekari, R. Ouimet, Z. Zeng, H. Yu, S. Bliznakov, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, and R. Maric, “High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment,” international journal of hydrogen energy, vol. 46, no. 2, pp. 1526–1539, 2021.Z. Zeng, R. Ouimet, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, A. P. Soleymani, J. Jankovic, H. Yu, G. Mirshekari, et al., “Degradation mechanisms in advanced meas for pem water electrolyzers fabricated by reactive spray deposition technology,” Journal of The Electrochemical Society, vol. 169, no. 5, p. 054536, 2022.A. Martin, D. Abbas, P. Trinke, T. Böhm, M. Bierling, B. Bensmann, S. Thiele, and R. Hanke-Rauschenbach, “Communication—proving the importance of ptinterlayer position in pemwe membranes for the effective reduction of the anodic hydrogen content,” Journal of The Electrochemical Society, vol. 168, no. 9, p. 094509, 2021.R. J. Ouimet, “Catalyst development by a novel fabrication process for energy applications,” University of Connecticut Doctoral Dissertation, 2021.P. Trinke, P. Haug, J. Brauns, B. Bensmann, R. Hanke-Rauschenbach, and T. Turek, “Hydrogen crossover in pem and alkaline water electrolysis: mechanisms, direct comparison and mitigation strategies,” Journal of The Electrochemical Society, vol. 165, no. 7, p. F502, 2018.P. Trinke, B. Bensmann, and R. Hanke-Rauschenbach, “Current density effect on hydrogen permeation in pem water electrolyzers,” International Journal of Hydrogen Energy, vol. 42, no. 21, pp. 14355–14366, 2017.H. Q. Nguyen and B. Shabani, “Proton exchange membrane fuel cells heat recovery opportunities for combined heating/cooling and power applications,” Energy Conversion and Management, vol. 204, p. 112328, 2020.C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K. D. Kreuer, and S. Vierrath, “All-hydrocarbon mea for pem water electrolysis combining low hydrogen crossover and high efficiency,” Advanced Energy Materials, vol. 10, no. 14, p. 1903995, 2020.

The global push towards cleaner energy sources has heightened the demand for high-performing, durable proton exchange membrane water electrolyzer (PEMWE) electrocatalysts. Green hydrogen, generated through water electrolysis powered by renewable energy, stands as a prominent solution in this endeavor to transition away from fossil fuels. Among various electrolyzer technologies, PEMWE systems currently offer the most competitive pathway for green hydrogen production. These systems typically employ a platinum on carbon supported (Pt/C) cathodic electrocatalyst for the hydrogen evolution reaction (HER) and an iridium oxide (IrOx) anodic electrocatalyst for the oxygen evolution reaction (OER). Efforts to enhance PEMWE performance primarily focus on improving the kinetics of the OER process, which accounts for the majority of activation overpotential during operation. To address cost concerns associated with IrOx, researchers are exploring alternative formulations, including doping with materials like niobium (Nb), aiming for comparable performance at reduced Ir loading [1], [2], [3]. It is argued that higher surface area and lower crystalline IrOx catalysts lead to lower activation overpotentials and enhanced durability, respectively. In this study, we investigate the performance of high-surface-area IrOx electrocatalysts (>200 m2/g) and Nb-doped IrOx variants, comparing them with commercially available benchmarks. Through rigorous examination utilizing Rotating Disk Electrode (RDE), Gas Diffusion Electrode (GDE) half-cell, and Membrane Electrode Assemblies (MEAs), we report on the performance and stability of our in-house prepared materials. Preliminary results examining various loadings of IrOx suggest that lower loadings lead to durable and active electrocatalyst layers. Our findings underscore the potential of Nb-doped IrOx as a cost-effective alternative for PEMWE electrocatalysts, offering promising advancements in the pursuit of efficient and sustainable hydrogen production.

Membrane failure is a serious safety concern that influences the operational lifetime and hydrogen production cost of the proton exchange membrane (PEM) water electrolyzer. The membrane degradation is nuanced, and the causes are multifaceted. A two-phase flow of oxygen and water is induced at the anode under a high operating current density (2-3 A cm-2). The oxygen gas crossover from the anode to the cathode occurs by convection or diffusion 1,2. The oxygen reacts at Pt active sites at the cathode and forms H2O2, which, in the presence of metal ion contaminants, forms harmful radicals that attack the side-chain of the perfluorosulfonic acid (PFSA) ionomer membrane, leading to membrane thinning via an unzipping reaction 3,4. The oxygen permeability through the membrane increases owing to membrane thinning and membrane degradation, which leads to the formation of a combustible gas mixture, causing electrolyzer shutdown. Moreover, the physical and electrochemical interface between the porous transport layer (PTL) and the catalyst-coated membrane (CCM) plays a crucial role in governing the stability of the membrane. A poorly designed PTL-CCM interface induces high ohmic and activation overpotential owing to oxygen accumulation, which in turn leads to poor reactant access by masking of catalyst reaction sites and local overheating accelerating the interface degradation. The condition further aggravates catalyst agglomeration and delamination from the membrane, resulting in local hotspot formation and possibly exacerbating local membrane degradation 5–8. The 2D visualization using a scanning electron microscope (SEM) is insufficient to capture the multifaceted cause of membrane degradation. In-situ X-ray computed tomography (XCT) is a non-destructive technique that serves as a 3D visualization tool to improve the fundamental understanding of membrane degradation 9,10.The present study aims to develop a miniaturized cell for a PEM water electrolyzer for simultaneous in-situ XCT visualization of the membrane, catalyst layers, and PTLs. The conventional PEM water electrolyzer hardware comprises a titanium bipolar plate, which attenuates X-rays, rendering it unsuitable for XCT visualization. The miniaturized cell hardware is additively manufactured and encompasses the flow fields. A platinized titanium mesh is used as a current collector that allows XCT imaging of PEM water electrolyzer components in the miniaturized cell. In-situ XCT imaging facilitates the root cause diagnosis for membrane degradation via membrane thinning and oxygen gas crossover. The beginning-of-life (BOL) performance of the miniaturized cell is evaluated at 60 °C. The commercially fabricated CCM (Ion Power Inc.) consisted of a Nafion 115 membrane with catalyst loading of 0.5 mg cm-2 Pt/C (40 wt% Pt) at cathode and 1 mg cm-2 at IrOx anode. The diffusion layers comprised a 250 µm thick platinized titanium PTL (Bekaert) at the anode and 410 µm thick carbon cloth with a microporous layer (FuelCellStore) at the cathode. A polarization curve and galvanostatic electrochemical impedance spectroscopy (GEIS) are obtained at 60 °C to determine the BOL performance of the miniaturized cell (Figure 1). Stressors for degradation are imposed to obtain a degradation mechanism of the membrane, which is based on the intertwining relationship between the membrane’s chemical/mechanical aspects and the PTL-CCM interface using the XCT visualization. Electrochemical characterizations are performed to evaluate the beginning-of-life (BOL) and end-of-life (EOL) performance of the PEM water electrolyzers, which is correlated against the observed membrane degradation mechanisms. Acknowledgments The research was supported by the National Research Council, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Western Economic Diversification Canada, Pacific Economic Development Canada, and Canada Research Chairs. References P. Trinke, B. Bensmann, and R. Hanke-Rauschenbach, Electrochem commun, 82, 98–102 (2017).M. Schalenbach, M. Carmo, D. L. Fritz, J. Mergel, and D. Stolten, Int J Hydrogen Energy, 38, 14921–14933 (2013).T. Sugawara, N. Kawashima, and T. N. Murakami, J Power Sources, 196, 2615–2620 (2011).T. Xie and C. A. Hayden, Polymer (Guildf), 48, 5497–5506 (2007).A. Bazarah et al., Int J Hydrogen Energy, 47, 35976–35989 (2022).D. Kulkarni et al., Appl Catal B, 308 (2022).J. T. Lang et al., Chem Rev (2022).C. Liu et al., J Electrochem Soc, 170, 034508 (2023).Y. Chen et al., J Electrochem Soc, 170, 114526 (2023).N. Kumar et al., J Electrochem Soc, 171, 074513 (2024). Figure 1

Proton exchange membrane (PEM) water electrolysis offers significant potential for sustainable production of green hydrogen due to its high current density, superior hydrogen purity, and excellent conversion efficiency. However, widespread industrial implementation remains challenging because state-of-the-art oxygen evolution reaction (OER) catalysts heavily rely on iridium, a precious metal with limited global supply and high costs.1–4 Therefore, considerable research efforts have been dedicated to developing new catalysts requiring lower iridium loadings. Although PEM electrolysis typically operates at elevated temperatures (50-80°C),1 most studies assessing catalyst activity and stability have been performed at room temperature, and the limited available temperature-dependent studies primarily focus on alkaline environments.5,6 In this work, we have systematically investigated the temperature-dependent activity and stability of two representative Ir-based catalysts: a commercial IrO₂ catalyst and a supported core-shell Ir@IrOₓ catalyst. Using a high-temperature rotating-disk electrode (RDE) setup, electrochemical assessments of the activity and stability of the catalysts were performed across a range of operating temperatures from 20°C up to 80°C. We investigated how the increased operating temperature affects the OER activities of these two catalysts, observing not only enhanced kinetics with the increased working temperatures but also altered reaction mechanisms, as indicated by the Tafel analysis of the OER polarization curves. Furthermore, by employing an accelerated stress test protocol, we evaluated the stability of the two catalysts under varied temperatures. Comprehensive in-situ and post-mortem characterization techniques, including in-situ XRD, XPS (Figure 1), TEM, and ICP, were employed to investigate the structural changes of the catalysts during the stability tests, which revealed the accelerated degradation at higher working temperatures, but also the surprisingly high OER stability of the core-shell Ir@IrOx structure under high working temperatures.Figure 1: Comparison the Ir 4f XPS spectra of the sample before and after the stability test at 60 °C.References Carmo, M., Fritz, D. L., Mergel, J. & Stolten, D. A comprehensive review on PEM water electrolysis. Int J Hydrogen Energy 38, 4901–4934 (2013). Wang, C. & Feng, L. Recent advances and perspectives of Ir-based anode catalysts in PEM water electrolysis. Energy Advances 3, 14–29 (2024). Kibsgaard, J. & Chorkendorff, I. Considerations for the scaling-up of water splitting catalysts. Nature Energy 2019 4:6 4, 430–433 (2019). Reier, T., Oezaslan, M. & Strasser, P. Electrocatalytic oxygen evolution reaction (OER) on Ru, Ir, and pt catalysts: A comparative study of nanoparticles and bulk materials. ACS Catal 2, 1765–1772 (2012). Shi, G. et al. Temperature Dependence of Oxygen Evolution Reaction Activity in Alkaline Solution at Ni-Co Oxide Catalysts with Amorphous/Crystalline Surfaces. ACS Catal 12, 14209–14219 (2022). Lyu, X., Li, J., Yang, J. & Serov, A. Significance of slight ambient temperature variation on the electrocatalyst performance toward oxygen evolution reaction. J Environ Chem Eng 11, 111492 (2023). Figure 1

Mathematical modeling of an integrated photovoltaic-assisted PEM water electrolyzer system for hydrogen production

Proton exchange membrane (PEM) water electrolysis has emerged as a pivotal technology for sustainable hydrogen production, offering a clean and efficient pathway to generate hydrogen from water using renewable energy sources. Novel Pt/C catalysts fabricated via fluidized bed reactor atomic layer deposition (FBR-ALD) present promising advancements for PEM water electrolyzer cathode catalyst layers. The process enables a uniform and controllable deposition of Pt nanoparticles onto carbon support materials, enhancing catalytic activity and stability [1]. The resulting catalysts demonstrate improved electrochemical performance in PEM water electrolysis, attributed to optimized Pt dispersion and enhanced catalytic sites [2]. This study explores the synthesis and further processing of these catalysts into catalyst inks and subsequently cathode catalyst layers for water electrolysis, leveraging the precise control and scalability offered by FBR-ALD to minimize the Pt loading while maintaining high catalytic activity and performance. Detailed layer characterization techniques, including atomic force microscopy (AFM) and electrochemical analyses, elucidate the structural and electrochemical properties of the Pt/C catalysts. Insights gained from this research contribute to a decrease in expensive platinum group metal employment and the scalable development of efficient, cost-effective, and durable catalyst materials for hydrogen production through PEM water electrolysis.[1] F. Grillo, H. Van Bui, J. A. Moulijn, M. T. Kreutzer, and J. R. van Ommen, “Understanding and Controlling the Aggregative Growth of Platinum Nanoparticles in Atomic Layer Deposition: An Avenue to Size Selection,” J. Phys. Chem. Lett., vol. 8, no. 5, 2017. doi: 10.1021/acs.jpclett.6b02978.[2] W.-J. Lee, S. Bera, H.-C. Shin, W.-P. Hong, S.-J. Oh, Z. Wan, S.-H. Kwon, Uniform and Size-Controlled Synthesis of Pt Nanoparticle Catalyst by Fluidized Bed Reactor Atomic Layer Deposition for PEMFCs. Adv. Mater. Interfaces 2019, 6, 1901210. doi: 10.1002/admi.201901210

The high cost of noble metals is one of the key factors hindering the large‐scale application of proton exchange membrane (PEM) water electrolyzer for hydrogen production. Recently, single‐atom catalysts (SACs) with a potential of maximum atom utilization efficiency enable lowering the metal amount as much as possible; unfortunately, their durability remains a challenge under PEM water electrolyzer working conditions. Herein, a highly‐stable alloyed Pt SAC is demonstrated through a plasma‐assisted alloying strategy and applies to a PEM water electrolyzer. In this catalyst, single Pt atoms are firmly anchored onto a Ru support via a robust metal–metal bonding strength, as evidenced by these complementary characterizations. This SAC is used in a PEM water electrolyzer system to achieve a cell voltage as low as 1.8 V at 1000 mA cm−2. Impressively, it can operate over 1000 h without obvious decay, and the catalyst is present in the form of individual Pt atoms. To the knowledge, this will be the first SAC attempt at a cell level toward long‐term PEM. This work paves the way for designing durable SACs employed in the actual working condition in the PEM water electrolyzer.

Magnetically modified electrocatalysts for oxygen evolution reaction in proton exchange membrane (PEM) water electrolyzers

Hydrogen, as a clean energy carrier, is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies, has ignited much attention in the past decades based on the high current density, greater energy efficiency, small mass-volume characteristic, easy handling and maintenance. To date, substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review, we firstly compare the alkaline water electrolysis (AWE), solid oxide electrolysis (SOE), and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore, we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly, current collector, and bipolar plate). Finally, the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.

Plug is building an end-to-end green hydrogen ecosystem to help its customers meet their business goals and decarbonize the economy. This hydrogen ecosystem is inclusive of hydrogen production, hydrogen storage, hydrogen delivery, and energy generation. As the largest user of liquid hydrogen globally, Plug Power plans to build and operate green hydrogen production plants across North America and Europe. Plug’s hydrogen production plants are based on electrolyzer systems featuring internally developed proton exchange membrane (PEM) water electrolyzer membrane electrode assemblies (MEAs). Recently, Plug has evaluated a spark ablation-based porous transport electrode (PTE) in water electrolyzer MEA. Spark ablation has been described by others [1]. This paper will review the evaluation of this PTE-based MEA. The general advantages and disadvantages of PTE-based water electrolyzer MEAs will also be discussed.The PTE-based MEA features catalyst generated by a spark ablation technique developed by VSPARTICLE. This technique allows for the generation of nanoparticles directly from metal ingots. The MEA consists of a Toray-based gas diffusion electrode (GDE) cathode with approximately 0.2 mg/cm2 supported platinum, a catalyst coated membrane (CCM) with approximately 0.4 mg/cm2 of iridium deposited via spark ablation, and a catalyst coated Bekaert porous transport layer (PTL) to form the PTE. The PTE catalyst loading is approximately 0.4 mg/cm2 of iridium deposited via spark ablation. The total anode loading for the MEA is approximately 0.8 mg/cm2. The MEA uses Chemours Nafion 115 as the PEM.The MEA is installed in a 25 cm² active area cell using the open-source design from the National Renewable Energy Laboratory (NREL). A current-voltage polarization curve for the cell is shown as Figure 1. The cell can achieve a voltage of 1.93 Volts at an applied current density of 3 A/cm2 when operated at 80 oC, 0 PSIG backpressure. The cell voltage is in family with other cells feature MEAs fabricated from Nafion 115 [2]. Durability testing of the cell is shown as Figure 2. Durability testing is conducted at an applied current density of 2 A/cm2, 80 oC, and 0 PSIG backpressure. The estimated degradation rate during testing is approximately 4 mV/khr.PTEs manufactured via spark ablation, or other physical vapor deposition techniques, allow for minimum use of catalyst. These deposition techniques may help reduce costs in water electrolyzer cells. They may also be more tolerant to ionomer-driven MEA degradation pathways as none is present in the catalyst layer. Lastly, these deposition techniques may provide a uniformity of coating at low catalyst loadings which is superior to other catalyst deposition techniques. Uniformity of catalyst coatings on PTEs may be key in enabling durability as hotspots could be reduced at the catalyst-membrane interface, reducing the chance of pinhole formation on the PEM. Reducing, or eliminating hotspot, at the catalyst-membrane interface is specifically important in water electrolyzer MEAs featuring thin (≤ 50 µm) PEMs operating at elevated current densities (≥ 1 A/cm2).

PETRONAS has embarked upon hydrogen production technology development, such as Proton Exchange Membrane (PEM) electrolyzers, to achieve an ambitious target of net-zero carbon emissions by 2050. This initiative aligns with PETRONAS and SLB’s aspiration to offer sustainable solutions in the energy business. In this journey, PETRONAS collaborated with SLB (vendor) in developing process simulation models and conducting analysis of the results/findings. PEM electrolyzers are considered among the most favorable technologies for hydrogen generation. PEM electrolyzers already commercially available and present many advantages over other available water electrolysis technologies, including simplicity, higher current densities, solid electrolytes, and higher working pressures. They are expected to be a future alternative to conventional alkaline water electrolyzers in low-temperature applications. This study focuses on PEM electrolyzers for hydrogen (H2) production by employing a comprehensive approach to investigate the behavior and performance of PEM electrolyzers through rigorous steady-state simulation. The aim is to validate the electrolyzer model in the process simulator Symmetry-iCON (SLB’s proprietary software), evaluate operational parameters, and predict system behavior under various operating conditions. The steady-state simulation results provide critical insights into PEM behavior and performance dynamics. Additionally, the findings emphasize the significant influence of operating temperature on H2 production rates and power consumption efficiency. An increase in the electrolyzer's operating temperature has been shown to increase H2 production rates while concurrently reducing power consumption per unit of H2 production. Furthermore, evaluating a decay rate of 4mA/cm2-h highlighted the impact of membrane deterioration over time, leading to a reduction in H2 production and increased power consumption per unit of H2. Remarkably accuracy with error rate below 1%, reinforcing the reliability of predictions. The study's significance lies in the key role of steady-state simulation and analysis for predicting system stability, optimizing efficiency, and ensuring consistent hydrogen production. Understanding the correlation between operating temperature and H2 production rate enables the selection of optimal conditions for improved efficiency. Additionally, the decay rates assist in predicting long-term performance trends, facilitating maintenance decisions of PEM membranes to sustain optimal electrolyzer performance. The key findings from this study were further used and integrated for scaling up the model into larger-scale systems, providing comprehensive insights into the broader implications of the electrolyzer's performance. The sensitivity analysis conducted further enriched the understanding of the electrolyzer's behavior under various operational parameters, offering crucial data for real-world applications. In summary, this study not only reveals the behavior of PEM electrolyzers concerning operational parameters but also emphasizes their integration into larger-scale systems. The findings underscore the necessity of steady-state simulation in optimizing performance and advancing sustainable hydrogen production, aligning with PETRONAS's commitment to pioneering sustainable technology in achieving net-zero carbon emissions.

First pulsed control system design for enhanced hydrogen production performance in proton exchange membrane water electrolyzers

Proton exchange membrane (PEM) water electrolysis has become increasingly attractive due to the penetration of renewable energy (e.g, solar and wind). Hydrogen production from PEM water electrolysis is advantageous over other technologies due to its simple and clean nature. Membrane and electrode assemblies (MEAs) of PEM electrolyzers typically use iridium (Ir) as an anode catalyst and Pt as a cathode catalyst. Performance and durability of the MEAs play an essential role for the cost and viable commercialization of PEM water electrolysis. However, unlike the well-established MEA benchmarks of PEM fuel cells, the performance and durability of PEM electrolyzer MEAs have not been thoroughly studied. The objective of this work is to establish benchmark MEA performance and durability for PEM water electrolysis. For this purpose, a series of oxygen evolution reaction (OER) catalysts, which includes commercial Ir black and various Ir nanostructures, has been evaluated under test protocols established at Giner Inc. These approaches include high-voltage hold (>1.8 V), accelerated stress test (e.g., voltage cycling from 1.4 to 2.0 V), and constant low-current operations. The polarization curves of the MEAs will be obtained after each test. The morphology and structure of MEAs after durability tests will be characterized to correlate to their performance and durability. The established performance and durability may provide metrics and guidance to the community of PEM water electrolysis. Acknowledgement: The financial support is from the Department of Energy under the Contract Grant DE-SC0007471.