Proton Exchange Membrane Electrolyzer Research Articles

Exploring pyrolusite β-MnO2 as a robust support for noble metal catalysts in proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis (PEMWE) represents a promising avenue for producing hydrogen sustainably. Nonetheless, its widespread adoption encounters hurdles owing to the sluggishness of the oxygen evolution reaction (OER) and the expensive noble metal catalysts, particularly iridium (Ir). Our investigation addresses these challenges by examining pyrolusite β-MnO2 as a robust substrate for noble metal catalysts, including iridium (Ir) and ruthenium (Ru), within PEMWE systems. We illustrate that nanostructured β-MnO2 effectively supports Ir and Ru catalysts, resulting in significantly improved catalytic activity for acidic OER compared to conventional IrO2 catalysts. The morphology shows nanorod structures with thicknesses ranging of 30–60 nm. The catalytic activity exhibits a lower overpotential of 215 mV and a higher Ir mass activity of 2268.7 A·gIr−1. The catalyst also exhibits lower Tafel slope value (37.82 mV/dec) and higher reaction kinetics. The catalyst also shows durability for the 12h under corrosive acidic OER conditions. The enhancements in performance can be attributed to the distinctive nanostructure of the Mn1-xTixO2 (MTO) support, which facilitates the even distribution of Ir and Ru catalysts. Additionally, the incorporation of titanium in pyrolusite β-MnO2 enhances the electrochemical durability of the MTO support under challenging acidic OER conditions.

Na-doped cobalt spinel electrocatalysts prepared by programmed electrostatic spraying for improving OER activity and durability in acidic media

The daunting challenge to establish a trade-off among the activity, durability, and cost of electrocatalysts for oxygen evolution reaction (OER) with sluggish reaction kinetics impedes the practical green energy conversion. Hereby, a non-noble metal-based electrocatalyst (i.e., Na-doped Co3O4) was in-situ prepared by programmed electrostatic spraying as an advanced alternative to the costly and scarce state-of-the-art IrO2 and RuO2-based electrocatalysts. The utilization of this sprayer facilitates intimate contact with the substrate electrode and provides short ion diffusion paths, facilitating efficient electron transport. Additionally, the doping of Na ions into the Co3O4 structure results in structural distortion and charge redistribution, leading to the generation of oxygen vacancies (OVs). These OVs enhance the activity of lattice oxygen atoms, thus enabling rapid and durable oxygen evolution in an acidic media (0.5 M H2SO4). The optimal Na-Co3O4 (AA) exhibits a notably low overpotential of 360 mV@10 mA·cm−2 and at least 200 h stability. In addition, density functional theory (DFT) calculations confirm that the incorporation of Na ions significantly elevates electrical conductivity by decreasing the energy band gap and reduces the free energy barrier for the conversion of *O to *OOH, thereby improving the intrinsic OER activity. Finally, by implanting the catalyst in a single-cell proton exchange membrane water electrolyzer (PEMWE), the current density of 100 mA·cm−2 is achieved at a voltage of 1.62 V. This innovative non-noble metal catalyst holds great potential for scalable PEMWE anodes.

Facet Engineering of Cobalt Manganese Oxide for Highly Stable Acidic Oxygen Evolution Reaction

AbstractDeveloping cost‐effective, robust, and durable catalysts for water oxidation in acidic conditions remains a significant challenge for the practical application of proton exchange membrane electrolyzers. Cobalt‐based spinel catalysts, known for their effective oxygen evolution reaction (OER) activity in acidic environments, are promising alternatives to the costly iridium‐based catalysts. However, their application is often limited by poor stability under corrosive acidic conditions and oxidative potential. Here it is demonstrated that doping Co2MnO4 with Ni effectively regulates the structural and electronic properties of the catalysts, enabling stable operation for over 285 h at 100 mA cm−2 in 0.5 m H2SO4. This stability enhancement is primarily due to the increased exposure of the (400) facet, a result supported by theoretical studies. The proton exchange membrane water electrolysis (PEMWE) performance of Ni(5%)Co2MnO4 further demonstrates its potential, achieving 1 A cm−2 at a cell voltage of 2.3 V, with minimal degradation over 100 h at 500 mA cm−2. This study not only provides insights into the design of advanced OER catalysts through the doping of heteroatoms but also offers a pathway to enhance the sustainability and economic viability of acidic OER applications.

Proton exchange membrane‐based electrocatalytic systems for hydrogen production

AbstractHydrogen energy from electrocatalysis driven by sustainable energy has emerged as a solution against the background of carbon neutrality. Proton exchange membrane (PEM)‐based electrocatalytic systems represent a promising technology for hydrogen production, which is equipped to combine efficiently with intermittent electricity from renewable energy sources. In this review, PEM‐based electrocatalytic systems for H2 production are summarized systematically from low to high operating temperature systems. When the operating temperature is below 130°C, the representative device is a PEM water electrolyzer; its core components and respective functions, research status, and design strategies of key materials especially in electrocatalysts are presented and discussed. However, strong acidity, highly oxidative operating conditions, and the sluggish kinetics of the anode reaction of PEM water electrolyzers have limited their further development and shifted our attention to higher operating temperature PEM systems. Increasing the temperature of PEM‐based electrocatalytic systems can cause an increase in current density, accelerate reaction kinetics and gas transport and reduce the ohmic value, activation losses, ΔGH*, and power consumption. Moreover, further increasing the operating temperature (120–300°C) of PEM‐based devices endows various hydrogen carriers (e.g., methanol, ethanol, and ammonia) with electrolysis, offering a new opportunity to produce hydrogen using PEM‐based electrocatalytic systems. Finally, several future directions and prospects for developing PEM‐based electrocatalytic systems for H2 production are proposed through devoting more efforts to the key components of devices and reduction of costs.

New hybrid system of PV/T, solar collectors, PEM electrolyzer, and HDH for hydrogen and freshwater production: Seasonal performance investigation

A new hybrid energy system of PV/T, flat plate collector, PEM electrolyzer, and humidification-dehumidification desalination is introduced here. A comprehensive mathematical model for the system seasonal performance is constructed and solved numerically using MATLAB software. A year-round comparison between the traditional PV/T performance and its concentrated counterpart indicates that the latter performs better compared to power, hydrogen, and freshwater production and system overall efficiency. The maximum monthly achieved PV/T efficiency, electrolyzer efficiency, desalination system Gain Output Ratio, and overall system efficiency are 52 %, 62 %, 4.8 %, and 44 %, respectively at a concentration ratio of 4 and maximum allowable PV temperature. The system produces 82,200 kWh of energy annually and provides 77,700 kWh and 1500 kWh to the electrolyzer and the electric heater, respectively. Moreover, the system produces an annual freshwater production of about 52,700 kg, out of which approximately 10,000 kg are consumed in the electrolysis process, and an annual hydrogen production of approximately 1120 kg.

Trimetallic RuAuMo Thin-film Electrocatalyst Synthesized via Co-sputtering for Proton Exchange Membrane Water Electrolysis

Trimetallic RuAuMo Thin-film Electrocatalyst Synthesized via Co-sputtering for Proton Exchange Membrane Water Electrolysis

Nitrogen-doped carbon nanosheet confined PtNi alloy for efficient acidic electrocatalytic hydrogen evolution reaction

Low intrinsic electrocatalytic activity and inferior conductivity limit the application of Ni/NC in acidic electrocatalytic hydrogen evolution reaction (HER). Herein, we prepared nitrogen-doped carbon nanosheet confined PtNi alloy electrocatalysts (PtNi/NC-10) using PtCl62− electrostatic adsorption coupling melamine pyrolysis nitriding strategy. PtNi alloying was confirmed by the crystallinity decrease and lattice expansion of Ni/NC. The alloying and confinement effect of Metal-Organic Frameworks (MOFs) suppresses the oxidation and agglomeration of metal nanoparticles during pyrolysis, thus significantly reducing particle size, increasing specific surface area, and promoting the exposure of active sites. The strong electronic interaction between Pt and Ni optimizeds the surface charge distribution, enhancing the adsorption of H species on electron-rich Pt sites, thereby improving reaction kinetics. In addition, PtNi alloying improves the conductivity of the material, accelerating charge transfer and proton transport. Consequently, the prepared PtNi/NC-10 exhibits superior HER performance than Ni/NC in 0.5 M H2SO4 solution, even comparable to commercial 20 wt% Pt/C, with the overpotentials of 35 mV at 0.01 A cm−2. Furthermore, the electrocatalysts assembled PtNi/NC-10-CP‖RuO2-TFF proton exchange membrane (PEM) electrolyzer only requires 2.32 V cell voltage to achieve 1 A cm−2, presenting practical application prospects. Our work provides a novel idea for designing efficient and stable MOFs confined to alloy-based HER electrocatalysts.

Influence of membrane cathode assembly composition and fabrication methods on proton exchange membrane electrolyzers for electrochemical toluene hydrogenation

Influence of membrane cathode assembly composition and fabrication methods on proton exchange membrane electrolyzers for electrochemical toluene hydrogenation

A method for configuring hybrid electrolyzers based on joint wind and photovoltaic power generation modeling using copula functions

Considering the specific wind and photovoltaic power characteristics of a certain region, this study investigates the optimal ratio of Alkaline Electrolysis Cells (AEL) to Proton Exchange Membrane (PEM) electrolyzers in a hybrid electrolysis system for hydrogen production. A flexible model for configuring the hybrid electrolysis system is proposed, based on a copula function for joint wind and solar power modeling. This model generates wind and photovoltaic power generation scenarios using the copula function, incorporating a selection mechanism to ensure that the output scenarios are more representative of the actual data characteristics of wind and photovoltaic power output. Consequently, considering both the fluctuation and amplitude, the wind and photovoltaic power data are decomposed using the Ensemble empirical mode decomposition method. The decomposed components are then allocated to the two types of electrolyzers. Furthermore, the optimal configuration of the hybrid electrolysis system is determined by minimizing the costs associated with wasted power, electricity purchases, and other expenses. Finally, a case study of a 100 MW wind farm and a 50 MW photovoltaic power station in Northwest China is presented, concluding that the optimal configuration ratio of AEL to PEM electrolyzers is 2:1. In a Matlab/Simulink platform, the performance metrics of the hybrid electrolysis system were validated. It was found that the hydrogen production rate of the hybrid electrolyzer is comparable to that of the PEM electrolyzer, but with a lower required cost. Additionally, the hydrogen production rate and volume of the optimal configuration for the hybrid electrolyzer determined by the model proposed in this paper are higher than those obtained through the optimization algorithm's optimal configuration.

Techno economic analysis of electrolytic hydrogen production by alkaline and PEM electrolysers using MCDM methods

Hydrogen, a crucial clean and renewable energy source, addresses pressing challenges of energy security and environmental pollution. Water electrolysis for hydrogen production is a promising approach to satisfy the growing demand for sustainable energy. This study uniquely performs a comprehensive techno-economic analysis of hydrogen production using both Alkaline and Proton Exchange Membrane (PEM) electrolyzers, a first in the field to evaluate their performance comprehensively with advanced Multi-Criteria Decision-Making (MCDM) techniques. Leveraging TOPSIS, WASPAS interval methods, and the Best Worst Method (BWM) with fuzzy logic, this research introduces a novel evaluation framework that incorporates a wide-ranging set of factors, including environmental, technical, technological, economic, and social aspects, divided into 30 sub-criteria. These insights offer a comprehensive understanding of each electrolyser's strengths and weaknesses, helping stakeholders make informed decisions about cost reduction in hydrogen production technologies. This has not been done before. Although cost results favour Alkaline electrolysers, PEM electrolysers are attractive for specific applications where their benefits justify the higher initial cost, choosing between Alkaline and PEM electrolysers dependent on a given hydrogen production project's requirements.

Oxyanion Engineering on RuO2 for Efficient Proton Exchange Membrane Water Electrolysis.

In acidic proton exchange membrane water electrolysis (PEMWE), the anode oxygen evolution reaction (OER) catalysts rely heavily on the expensive and scarce iridium-based materials. Ruthenium dioxide (RuO2) with lower price and higher OER activity, has been explored for the similar task, but has been restricted by the poor stability. Herein, we developed an anion modification strategy to improve the OER performance of RuO2 in acidic media. The designed multicomponent catalyst based on sulfate anchored on RuO2/MoO3 displays a low overpotential of 190 mV at 10 mA cm-2 and stably operates for 500 hours with a very low degradation rate of 20 μV h-1 in acidic electrolyte. When assembled in a PEMWE cell, this catalyst as an anode shows an excellent stability at 500 mA cm-2 for 150 h. Experimental and theoretical results revealed that MoO3 could stabilize sulfate anion on RuO2 surface to suppress its leaching during OER. Such MoO3-anchored sulfate not only reduces the formation energy of *OOH intermediate on RuO2, but also impedes both the surface Ru and lattice oxygen loss, thereby achieving the high OER activity and exceptional durability.

Regulating Ru-O Bond and Oxygen Vacancies of RuO2 by Ta Doping for Electrocatalytic Oxygen Evolution in Acid Media.

Proton exchange membrane water electrolysis (PEMWE) is considered an ideal green hydrogen production technology with promising application prospects. However, the development of efficient and stable acid electroanalytic oxygen electrocatalysts is still a challenging bottleneck. This progress is achieved by adopting a strategic approach with the introduction of the high valence metal Ta to regulate the electronic configuration of RuO2 by manipulating its local microenvironment to optimize the stability and activity of the electrocatalysts. The Ta-RuO2 catalysts are notable for their excellent electrocatalytic activity, as evidenced by an overpotential of only 202 mV at 10 mA cm-2, which significantly exceeds that of homemade RuO2 and commercial RuO2. Furthermore, the Ta-RuO2 catalyst exhibits exceptional stability with negligible potential reduction observed after 50 h of electrolysis. Theoretical calculations show that the asymmetric configuration of Ru-O-Ta breaks the thermodynamic activity limitations usually associated with adsorption evolution, weakening the energy barrier for the formation of the OOH* formation. The strategic approach presented in this study provides an important reference for the development of a stable active center for acid water splitting.

Innovative multi-generation system producing liquid hydrogen and oxygen: Thermo-economic analysis and optimization using machine learning optimization technique

This research investigates the multi-objective optimization of a geothermal-driven multi-generation system designed to produce liquid hydrogen and oxygen as its primary outputs. The system incorporates a Proton Exchange Membrane (PEM) Electrolyzer alongside a modified ejector-based Organic Rankine Cycle to generate the required Energy (heating bar, cooling bar, electricity and hydrogen). Case studies were conducted in three distinct locations: Zanjan in Iran, Aarhus in Denmark, and San Bernardino in the United States, utilizing actual geological and meteorological data for accuracy. Simulations were executed applied Engineering Equation Solver & optimization of the system was carried out to enhance performance by focusing on the objective functions of system exergy efficiency and cost reduction. This was accomplished by utilizing response surface methodology (RSM) along with Minitab software (MS).To optimize the system, six decision variables were identified as critical parameters influencing performance. The optimization results indicated that the system can achieve an exergy efficiency of 53.74 % while maintaining a cost rate of $31.56 per hour. The overall cost rate for the geothermal system was determined to be $54.50 per hour, with $10.10 per hour allocated to hydrogen production and $44.40 per hour to electricity generation. Site-specific analyses highlighted San Bernardino as the most favorable location for implementing this system, projecting an annual production of 90.8 tons of liquid hydrogen and 208.3 kg of oxygen. In August, the geothermal system in San Bernardino can produce up to 7691.6 kg/h of liquid hydrogen, while in December, production decreases to 7402.8 kg/h, marking the lowest output for the year. In contrast, Zanjan and Aarhus demonstrated lower production capacities, underscoring the system's feasibility as dependent on site-specific conditions.

Interface-Strengthened Ru-Based Electrocatalyst for High-Efficiency Proton Exchange Membrane Water Electrolysis at Industrial-Level Current Density

Developing an OER electrocatalyst that balances high performance with low cost is crucial for widely adopting PEM water electrolyzers. Ru-based catalysts are gaining attention for their cost-effectiveness and high activity, positioning them as promising alternatives to Ir-based catalysts. However, Ru-based catalysts can be prone to oxidation at high potentials, compromising their durability. In this study, we utilize a simple synthesis method to synthesize a SnO2, Nb2O5, and RuO2 composite catalyst (SnO2/Nb2O5@RuO2) with multiple interfaces and abundant oxygen vacancies. The large surface area and numerous active sites of the SnO2/Nb2O5@RuO2 catalyst lead to outstanding acidic oxygen evolution reaction (OER) performance, achieving current densities of 10, 50, and 200 mA cm−2 at ultralow overpotentials of 287, 359, and 534 mV, respectively, significantly surpassing commercial IrO2. Moreover, incorporating Nb2O5 into the SnO2/Nb2O5@RuO2 alters the electronic structure at the interfaces and generates a high density of oxygen vacancies, markedly enhancing durability. Consequently, the membrane electrode composed of SnO2/Nb2O5@RuO2 and commercial Pt/C demonstrated stable operation in the PEM cell for 25 days at an industrial current density of 1 A cm−2. This research presents a convenient approach for developing a highly efficient and durable Ru-based electrocatalyst, underscoring its potential for proton exchange membrane water electrolysis.

Reducing noble metal content in water electrolysis catalysts: A study on high-entropy oxides

This study presents the development of high-entropy oxide (HEO) catalysts based on Iridium-Ruthenium oxides (IrRuOx) for the oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWEs). By incorporating 3d transition metals such as Fe, Co, and Ni, we achieved catalysts with enhanced performance and stability. Using density functional theory (DFT) calculations, we predicted that HEOs possess a more favorable electronic structure for catalytic reactions. The synthesized rutile-type HEO catalyst (RuIrFeCoNi)O2, created via a molten salt oxidation method, exhibited a low overpotential of 261 mV and excellent cycling stability, maintaining a stable voltage of 1.73 V at 1 A cm−2 over 100 hours of electrolysis. This innovative approach not only reduces noble metal content but also leverages multimetallic synergistic effects to optimize the catalytic performance and stability, offering a promising avenue for the industrial application of acidic water electrolysis in PEMWEs.

Physical Degradation of Anode Catalyst Layer in Proton Exchange Membrane Water Electrolysis

Physical Degradation of Anode Catalyst Layer in Proton Exchange Membrane Water Electrolysis

Oxidative reconstructed Ru-based nanoclusters forming heterostructures with lanthanide oxides for acidic water oxidation

Achieving rapid anodic oxygen evolution reaction (OER) kinetics and improving the stability of the corresponding ruthenium (Ru)-based catalysts is a current priority for the realisation of industrial water splitting. However, the activity and stability of O2 evolution in electrocatalysis are largely inhibited by the insufficient adsorption of the reactant H2O and too strong adsorption of the intermediate OOH*, as well as by the dissolution of the active site due to excessive oxidation. To solve this challenge, herein, we developed a regulatory strategy combining lanthanide oxides and metal oxidative reconfiguration. The introduction of Eu2O3 effectively promotes the adsorption of H2O, optimizes the adsorption energy of OOH*, and reduces the reaction energy barrier of acidic OER process. And the metal oxidation remodeling process exposed more active sites and prevented the peroxidation process. The optimized Ru/Eu2O3@CNT catalyst showed the highest catalytic activity and stability in acidic OER. Its mass activity was 1219.1 A gRu−1 and the TOF value reached 4.4 s−1 at 1.48 V. Additionally, Ru/Eu2O3@CNT after oxidative reconstruction demonstrates the industrially needed current density of 1.0 A cm−2 at 1.71 V in PEM electrolyser, achieving stability in excess of 200 h.

Strontium Doped IrOx Triggers Direct O-O Coupling to Boost Acid Water Oxidation Electrocatalysis.

The discovery of efficient and stable electrocatalysts for the oxygen evolution reaction (OER) in acidic conditions is crucial for the commercialization of proton-exchange membrane water electrolyzers. In this work, we propose a Sr(OH)2-assisted method to fabricate a (200) facet highly exposed strontium-doped IrOx catalyst to provide available adjacent iridium sites with lower Ir-O covalency. This design facilitates direct O-O coupling during the acidic water oxidation process, thereby circumventing the high energy barrier associated with the generation of *OOH intermediates. Benefiting from this advantage, the resulting Sr-IrOx catalyst exhibits an impressive overpotential of 207 mV at a current density of 10 mA cm-2 in 0.5 M H2SO4. Furthermore, a PEMWE device utilizing Sr-IrOx as the anodic catalyst demonstrates a cell voltage of 1.72 V at 1 A cm-2 and maintains excellent stability for over 500 hours. Our work not only provides guidance for the design of improved acidic OER catalysts but also encourages the development of iridium-based electrocatalysts with novel mechanisms for other electrocatalytic reactions.

Innovative application of transfer learning on small-scale datasets: Analysis and optimization of catalyst ink for the low-iridium membrane electrode assemblies of proton exchange membrane water electrolysis

The scarcity of Ir poses a significant barrier to the widespread adoption of proton exchange membrane water electrolysis (PEMWE), necessitating minimization of Ir loading in membrane electrode assemblies (MEAs). This study introduced a transfer learning strategy to optimize catalyst ink formulations for performance enhancement of low-Ir MEAs. We leveraged a pre-trained model from previous research and fine-tuned it on a small dataset of 12 MEAs’ ink preparation data, which significantly reduced labor, time, and costs associated with extensive experimentation. The developed model demonstrated high accuracy with an R2 of 0.99507. The parameters of the ink formulation were assessed using the Shapley Additive exPlanations method and optimized through the Harris Hawk Optimization algorithm. This optimization yielded an electrolysis voltage of 1.898 V at 3.0 A cm−2 for MEAs with 0.15 mg cm−2 Ir loading. These performance improvements are attributed to enhanced catalyst-ionomer particle dispersion and optimized rheological properties of the ink, which lead to more uniform distribution of Ir in the catalytic layers. These results demonstrate the feasibility and efficacy of transfer learning techniques to develop high-performance models from limited datasets, offering a promising pathway for accelerated materials discovery and optimization in the field of PEMWE.

Sulfonated poly(aryl ether) proton exchange membrane with excellent dimensional stability for hydrogen production by water electrolysis

The use of proton exchange membrane water electrolysis (PEMWE) for hydrogen production is considered a promising technology due to its high theoretical current density, gas purity, and energy efficiency. In this study, a fluorinated sulfonated hydrocarbon polymer was used to prepare hydrocarbon−based membranes for PEMWE that displayed exceptional stability. Notably, the SFPAE-60 membrane has a proton conductivity of up to 293.1 mS cm−2 at 80 °C and 100%RH, but its volumetric swelling ratio is only 47 %. Its dimensional stability is significantly better than that of previously reported sulfonated poly (aryl ether)−based proton exchange membranes (>100 %). The PEMWE based on the SFPAE-60 membrane achieves a current density of over 4800 mA cm−2 at 2.0V, confirming the membrane's applicability in actual water electrolysis. The results indicate that the electrolyte membrane of fluorinated sulfonated hydrocarbon polymer performs well in the PEM electrolyzer.