Proton Exchange Membrane Electrolyzer Research Articles

Quantification of electrochemically accessible iridium oxide surface area with mercury underpotential deposition

Research drives development of sustainable electrocatalytic technologies, but efforts are hindered by inconsistent reporting of advances in catalytic performance. Iridium-based oxide catalysts are widely studied for electrocatalytic technologies, particularly for the oxygen evolution reaction (OER) for proton exchange membrane water electrolysis, but insufficient techniques for quantifying electrochemically accessible iridium active sites impede accurate assessment of intrinsic activity improvements. We develop mercury underpotential deposition and stripping as a reversible electrochemical adsorption process to robustly quantify iridium sites and consistently normalize OER performance of benchmark IrO x electrodes to a single intrinsic activity curve, where other commonly used normalization methods cannot. Through rigorous deconvolution of mercury redox and reproportionation reactions, we extract net monolayer deposition and stripping of mercury on iridium sites throughout testing using a rotating ring disk electrode. This technique is a transformative method to standardize OER performance across a wide range of iridium-based materials and quantify electrochemical iridium active sites.

Honeycomb‐Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer

AbstractAchieving robust long‐term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low‐temperature synthesis of iridium oxide foam platelets comprising edge‐sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic‐to‐microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam‐like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single‐cell PEMWE based on honeycomb‐structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere‐level current densities and to remain stable for more than 2000 hours.

Techno-Economic Assessment of Hydrogen Production in Ghana through PV Electrolysis and Biomass Gasification

Abstract The potential to develop a green hydrogen market in Ghana is assessed in this paper. The focus is on biomass gasification and photovoltaic-driven water electrolysis. Using the H2A-Lite model, the technical, economic, and environmental aspects of these technologies are assessed for both current (2023) and future (2040) scenarios. In the current scenario, distributed and centralized Polymer Electrolyte Membrane (PEM) electrolysis gave levelized costs of $5.56/kg and $4.35/kg for hydrogen respectively, while centralized biomass gasification yields the cheapest hydrogen cost at $2.68/kg. The high cost of solar PEM electrolysis is linked to expensive electricity and solar PV, but also to compression, storage, and dispensing costs for distributed systems. By year 2040, a general cost reduction is expected due to cheaper renewable energy and increased efficiency. However, these production methods still face competition from more economical conventional steam methane reforming (SMR) processes having a levelized cost of less than $2/kg H2. The study concludes that a hydrogen development strategy and roadmap for Ghana will be crucial to proceed with hydrogen, setting deployment targets, and engaging stakeholders in promoting the use of hydrogen as an energy carrier while creating new economic opportunities and achieving climate objectives.

Data Hub for Life Cycle Assessment of Climate Change Solutions—Hydrogen Case Study

Life cycle assessment, which evaluates the complete life cycle of a product, is considered the standard methodological framework to evaluate the environmental performance of climate change solutions. However, significant challenges exist related to datasets used to quantify these environmental indicators. Although extensive research and commercial data on climate change technologies, pathways, and facilities exist, they are not readily available to practitioners of life cycle assessment in the right format and structure using an open platform. In this study, we propose a new open data hub platform for life cycle assessment, considering a hierarchical data flow starting with raw data collected on climate change technologies at laboratory, pilot, demonstration, or commercial scales to provide the information required for policy and decision-making. This platform makes data accessible at multiple levels for practitioners of life cycle assessment, while making data interoperable across platforms. The proposed data hub platform and workflow are explained through the polymer electrolyte membrane electrolysis hydrogen production as a case study. The climate change environment impact of 1.17 ± 0.03 kg CO2 eq./kg H2 was calculated for the case study. The current data hub platform is limited to evaluating environmental impacts; however, future additions of economic and social aspects are envisaged.

Honeycomb-Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer.

Achieving robust long-term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low-temperature synthesis of iridium oxide foam platelets comprising edge-sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic-to-microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam-like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single-cell PEMWE based on honeycomb-structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere-level current densities and to remain stable for more than 2000 hours.

Advancing Life Cycle Assessment of Sustainable Green Hydrogen Production Using Domain-Specific Fine-Tuning by Large Language Models Augmentation

Assessing the sustainable development of green hydrogen and assessing its potential environmental impacts using the Life Cycle Assessment is crucial. Challenges in LCA, like missing environmental data, are often addressed using machine learning, such as artificial neural networks. However, to find an ML solution, researchers need to read extensive literature or consult experts. This research demonstrates how customised LLMs, trained with domain-specific papers, can help researchers overcome these challenges. By starting small by consolidating papers focused on the LCA of proton exchange membrane water electrolysis, which produces green hydrogen, and ML applications in LCA. These papers are uploaded to OpenAI to create the LlamaIndex, enabling future queries. Using the LangChain framework, researchers query the customised model (GPT-3.5-turbo), receiving tailored responses. The results demonstrate that customised LLMs can assist researchers in providing suitable ML solutions to address data inaccuracies and gaps. The ability to quickly query an LLM and receive an integrated response across relevant sources presents an improvement over manually retrieving and reading individual papers. This shows that leveraging fine-tuned LLMs can empower researchers to conduct LCAs more efficiently and effectively.

Oxygen Vacancy-Electron Polarons Featured InSnRuO2 Oxides: Orderly and Concerted In-Ov-Ru-O-Sn Substructures for Acidic Water Oxidation.

Polymetallic oxides with extraordinary electrons/geometry structure ensembles, trimmed electron bands, and way-out coordination environments, built by an isomorphic substitution strategy, may create unique contributing to concertedly catalyze water oxidation, which is of great significance for proton exchange membrane water electrolysis (PEMWE). Herein, well-defined rutile InSnRuO2 oxides with density-controllable oxygen vacancy (Ov)-free electron polarons are firstly fabricated by in situ isomorphic substitution, using trivalent In species as Ov generators and the adjacent metal ions as electron donors to form orderly and concerted In-Ov-Ru-O-Sn substructures in the tetravalent oxides. For acidic water oxidation, the obtained InSnRuO2 displays an ultralow overpotential of 183 mV (versus RHE) and a mass activity (MA) of 103.02 A mgRu -1, respectively. For a long-term stability test of PEMWE, it can run at a low and unchangeable cell potential (1.56 V) for 200 h at 50 mA cm-2, far exceeding current IrO2||Pt/C assembly in 0.5 m H2SO4. Accelerated degradation testing results of PEMWE with pure water as the electrolyte show no significant increase in voltage even when the voltage is gradually increased from 1 to 5 A cm-2. The remarkably improved performance is associated with the concerted In-Ov-Ru-O-Sn substructures stabilized by the dense Ov-electron polarons, which synergistically activates band structure of oxygen species and adjacent Ru sites and then boosting the oxygen evolution kinetics. More importantly, the self-trapped Ov-electron polaron induces a decrease in the entropy and enthalpy, and efficiently hinder Ru atoms leaching by increasing the lattice atom diffusion energy barrier, achieves long-term stability of the oxide. This work may open a door to design next-generation Ru-based catalysts with polarons to create orderly and asymmetric substructures as active sites for efficient electrocatalysis in PEMWE application.

Clarify the process of overshoot voltage generation of proton exchange membrane electrolyzer under intermittent operation

Overshoot voltage phenomenon often occurs when the proton exchange membrane (PEM) electrolyzer is in the intermittent operation, which makes H2 production energy consumption increase significantly and its lifetime reduce rapidly, especially to the high-power electrolyzers in the industrial applications. Up to now, the phenomenon has been rarely understood and its process is elusive. Therefore, in this work, firstly, we find that the polarization curve of PEM electrolyzers happening S distortion synchronize with the appearance of overshoot voltage phenomenon. Secondly, through in-situ Raman characterization, we find that involvement and disappearance of H2O in the hydrogen evolution reaction (HER) is the key factor causing and resolving this phenomenon. Finally, we used EPMA to exclude metal cations affection. Also, by micro-CT, EIS test, visualization PEM electrolyzer inside model and COMSOL electromagnetic simulation, we find that anode catalyst layer porosity reduction directly affects water absorption of membrane as well as current variation leads to eddy currents generation which is deepen unequal current distribution. These are two important reasons for the involvement of H2O in HER. In summary, these findings elucidate the mechanism of overshoot voltage phenomenon for the first time, which contributes to design novel electrical protection schemes and advanced membrane electrodes for PEM electrolyzers, thus they can help to achieve cost reduction and efficiency improvement in the green hydrogen industry.

N-doped porous graphite with multilevel pore defects and ultra-high conductivity anchoring Pt nanoparticles for proton exchange membrane water electrolyzers

N-doped porous graphite with multilevel pore defects and ultra-high conductivity anchoring Pt nanoparticles for proton exchange membrane water electrolyzers

Exploiting the Ocean Thermal Energy Conversion (OTEC) technology for green hydrogen production and storage: Exergo-economic analysis

This study presents and analyses three plant configurations of the Ocean Thermal Energy Conversion (OTEC) technology. All the solutions are based on using the OTEC system to obtain hydrogen through an electrolyzer. The hydrogen is then compressed and stored. In the first and second layouts, a Rankine cycle with ammonia and a mixture of water and ethanol is utilised respectively; in the third layout, a Kalina cycle is considered. In each configuration, the OTEC cycle is coupled with a polymer electrolyte membrane (PEM) electrolyzer and the compression and storage system. The water entering the electrolyzer is pre-heated to 80 °C by a solar collector. Energy, exergy, and exergo-economic studies were conducted to evaluate the cost of producing, compressing, and storing hydrogen. A parametric analysis examining the main design constraints was performed based on the temperature range of the condenser, the mass flow ratio of hot and cold resource flows, and the mass fraction. The maximum value of the overall exergy efficiency calculated is equal to 93.5% for the Kalina cycle, and 0.524 €/kWh is the minimum cost of hydrogen production achieved. The results were compared with typical data from other hydrogen production systems.

Accurately prepared the large-area and efficiently 3D electrodes for overall seawater splitting

How to achieve accurately regulation of catalytic electrodes is the challenge of designing high-performance catalytic electrodes. In this work, large area, high stability and excellent conductivity electrode are prepared via one-step mild (298 K) electroplating method and precise control of electroplating parameters on nickel foam (FeNi@NF). The FeNi@NF electrode catalyst the hydrogen/oxygen evolution reaction (HER/OER) in simulate seawater (1.0 M KOH + 0.5 M NaCl), and achieves the current density of 100 mA cm−2 with only 287 mV and 323 mV overpotential. The alkaline electrolyzer drives 100 mA cm−2 for overall water splitting at a low voltage of 1.73 V. More importantly, the catalytic performance durable for more than 5 days at the industrial current density (1000 mA cm−2), and the designed large-area 25.0 cm2 catalytic electrode can achieve stable operation of industrial proton exchange membrane electrolyser. This preparation strategy provides a new idea for the current research of energy engineering and energy storage.

The influence of operating parameters on the performance of PEMWE electrolytic cell

Proton exchange membrane (PEM) is considered the most promising green hydrogen production technology in the future. The proton exchange membrane electrolysis cell (PEMEC) involves a complex process of multiple physical fields, including charge transfer, gas transfer, and heat transfer, during operation. Increasing the inlet water flow rate within a certain range is beneficial for increasing the output performance of the electrolysis cell and can also reduce the average temperature of the proton exchange membrane. But when the inlet flow rate increases to a certain amount, it has no effect. As the electrolysis voltage increases, the electrochemical performance of the electrolysis cell also increases, and the temperature of the proton exchange membrane and the current density of the catalytic layer also increase with the increase of voltage.

Optimization of Hydrogen Production System Performance Using Photovoltaic/Thermal-Coupled PEM

A proton exchange membrane electrolyzer can effectively utilize the electricity generated by intermittent solar power. Different methods of generating electricity may have different efficiencies and hydrogen production rates. Two coupled systems, namely, PV/T- and CPV/T-coupling PEMEC, respectively, are presented and compared in this study. A maximum power point tracking algorithm for the photovoltaic system is employed, and simulations are conducted based on the solar irradiation intensity and ambient temperature of a specific location on a particular day. The simulation results indicate that the hydrogen production is relatively high between 11:00 and 16:00, with a peak between 12:00 and 13:00. The maximum hydrogen production rate is 99.11 g/s and 29.02 g/s for the CPV/T-PEM and PV/T-PEM systems. The maximum energy efficiency of hydrogen production in CPV/T-PEM and PV/T-PEM systems is 66.7% and 70.6%. Under conditions of high solar irradiation intensity and ambient temperature, the system demonstrates higher total efficiency and greater hydrogen production. The CPV/T-PEM system achieves a maximum hydrogen production rate of 2240.41 kg/d, with a standard coal saving rate of 15.5 tons/day and a CO2 reduction rate of 38.0 tons/day. Compared to the PV/T-PEM system, the CPV/T-PEM system exhibits a higher hydrogen production rate. These findings provide valuable insights into the engineering application of photovoltaic/thermal-coupled hydrogen production technology and contribute to the advancement of this field.

Surface Corrosion‐Resistant and Multi‐Scenario MoNiP Electrode for Efficient Industrial‐Scale Seawater Splitting

AbstractThe construction of efficient and durable multifunctional electrodes for industrial‐scale hydrogen production presents a main challenge. Herein, molybdenum‐modulated phosphorus‐based catalytic electrodes (Mo‐NiP@NF) are prepared via mild electroless plating. Heteroatoms doping or heterostructures construction can reconfigure the intrinsic electronic structure of the pre‐catalyst and optimizes the key intermediates adsorption. Moreover, the (hypo/meta‐)phosphite anions (POxδ−) and molybdate ions (MoOxδ−) on the electrode surface of Mo‐NiP@NF afford resistance to chloride (Cl−) corrosion. Mo‐NiP@NF exhibits ultralow overpotentials of 278/550 and 282/590 mV at 1 A cm−2 during the hydrogen/oxygen evolution reaction (HER/OER) in alkaline simulated and real seawater, respectively, whereas catalytic overall seawater splitting (OWS) reach 1 A cm−2 at 1.96 and 1.97 Vcell. Remarkably, Mo‐NiP@NF maintains stable operation for 1500 h in OWS. The scalability of Mo‐NiP@NF allowing the assembly of proton exchange membrane (PEM) electrolyzer powered by photovoltaic energy, simulating a portable hydrogen‐oxygen respirator provides an oxygen/hydrogen flows of 160/320 mL min−1. Expanding further, the trace ruthenium‐loaded Mo‐NiP@NF catalyst sodium borohydride (NaBH4) hydrolysis achieving a hydrogen generation rate (HGR) of 11049.2 mL min−1 g−1. This work provides strategic innovations and optimization solutions for the economical and mild construction of multi‐scenario durable green energy conversion materials at industrial‐scale application.

A comparative study on the Lattice Boltzmann Method and the VoF-Continuum method for oxygen transport in the anodic porous transport layer of an electrolyzer

The optimization of Polymer Electrolyte Membrane (PEM) electrolyzers necessitates an intimate knowledge of the oxygen flows within the anodic porous transport layers (PTLs) to determine any possible reduction in performance. In this field, as experimental studies are cumbersome and expensive, numerical modeling has arisen as a viable alternative for studying the oxygen transport within the Anodic PTLs of a PEM electrolyzer. Amongst the various numerical modeling techniques, the Lattice Boltzmann Method (LBM) is gaining prominence for its effectiveness in analyzing fluid transport within porous media due to its mesoscopic nature and ease of implementation. This study utilizes the Shan-Chen LBM methodology to model the flow of oxygen within the Anodic PTL of a PEM electrolyzer and compares it against the Volume-of-Fluid-based Continuum Model. The results show that LBM can not only replicate the experimental studies accurately, but can also maintain its high accuracy at progressively shrinking length scales of PTLs, even at length scales where the VoF-based Continuum Model would run into accuracy issues. The high accuracy of the LBM model, combined with the simplicity of the LB algorithm makes LBM a powerful technique for simulating the microfluidic flows such as the flow of oxygen within the Anodic PTL of a PEM electrolyzer.

A Long‐Range Disordering RuO2 Catalyst for Highly Efficient Acidic Oxygen Evolution Electrocatalysis

AbstractNon‐iridium acid‐stabilized electrocatalysts for oxygen evolution reaction (OER) are crucial to reducing the cost of proton exchange membrane water electrolyzers (PEMWEs). Here, we report a strategy to modulate the stability of RuO2 by doping boron (B) atoms, leading to the preparation of a RuO2 catalyst with long‐range disorder (LD‐B/RuO2). The structure of long‐range disorder endowed LD‐B/RuO2 with a low overpotential of 175 mV and an ultra‐long stability, which can maintain OER for about 1.6 months at 10 mA cm−2 current density in 0.5 M H2SO4 with almost invariable performance. More importantly, a PEM electrolyzer using LD‐B/RuO2 as the anode demonstrated excellent performance, reaching 1000 mA cm−2 at 1.63 V with durability exceeding 300 h at 250 mA cm−2 current density. The introduction of B atoms induced the formation of a long‐range disordered structure and symmetry‐breaking B−Ru−O motifs, which enabled the catalyst structure to a certain toughness while simultaneously inducing the redistribution of electrons on the active center Ru, which jointly promoted and guaranteed the activity and long‐term stability of LD‐B/RuO2. This study provides a strategy to prepare long‐range disordered RuO2 acidic OER catalysts with high stability using B‐doping to perturb crystallinity, which opens potential possibilities for non‐iridium‐based PEMWE applications.

Operando Stable Palladium Hydride Nanoclusters Anchored on Tungsten Carbides Mediate Reverse Hydrogen Spillover for Hydrogen Evolution

AbstractProton exchange membrane (PEM) electrolysis holds great promise for green hydrogen production, but suffering from high loading of platinum‐group metals (PGM) for large‐scale deployment. Anchoring PGM‐based materials on supports can not only improve the atomic utilization of active sites but also enhance the intrinsic activity. However, in practical PEM electrolysis, it is still challenging to mediate hydrogen adsorption/desorption pathways with high coverage of hydrogen intermediates over catalyst surface. Here, operando generated stable palladium (Pd) hydride nanoclusters anchored on tungsten carbide (WCx) supports were constructed for hydrogen evolution in PEM electrolysis. Under PEM operando conditions, hydrogen intercalation induces formation of Pd hydrides (PdHx) featuring weakened hydrogen binding energy (HBE), thus triggering reverse hydrogen spillover from WCx (strong HBE) supports to PdHx sites, which have been evidenced by operando characterizations, electrochemical results and theoretical studies. This PdHx‐WCx material can be directly utilized as cathode electrocatalysts in PEM electrolysis with ultralow Pd loading of 0.022 mg cm−2, delivering the current density of 1 A cm−2 at the cell voltage of ~1.66 V and continuously running for 200 hours without obvious degradation. This innovative strategy via tuning the operando characteristics to mediate reverse hydrogen spillover provide new insights for designing high‐performance supported PGM‐based electrocatalysts.

Alkali Metal Iridates as Oxygen Evolution Catalysts Via Thermal Transformation of Amorphous Iridium (oxy)hydroxides.

AbstractEfficient water‐splitting is severely limited by the anodic oxygen evolution reaction (OER). Iridium oxides remain one of the only viable catalysts under acidic conditions due to their corrosion resistance. We have previously shown that heat‐treating high‐activity amorphous iridium oxyhydroxide in the presence of residual lithium carbonate leads to the formation of lithium‐layered iridium oxide, suppressing the formation of low‐activity crystalline rutile IrO2. We now report the synthesis of Na‐IrOx and K‐IrOx featuring similarly layered crystalline structures. Electrocatalytic tests confirm Li‐IrOx retains similar electrocatalytic activity to commercial amorphous IrO2 ⋅ 2H2O and with increasing size of the intercalated cation, the activity towards the OER decreases. However, the synthesised electrocatalysts that contain layers show greater stability than crystalline rutile IrO2 and amorphous IrO2 ⋅ 2H2O, suggesting these compounds could be viable alternatives for industrial PEM electrolysers where durability is a key performance measure.

Effect of the Cathodic Gas Diffusion Layer on the Performance of a Proton Exchange Membrane Electrolyzer

Hydrogen production through electrolysis using renewable resources is highly promising for reducing greenhouse gas emissions. While significant efforts have focused on developing more efficient and cost-effective catalysts to lower hydrogen production costs, catalysts are not the primary expense in electrolyzer fabrication. In the case of Proton Exchange Membrane Water Electrolyzers (PEMWEs), other components—such as the proton membrane, gas diffusion layer (GDL), and bipolar plates—contribute more to overall costs. To explore this, a study was conducted on the performance of PEMWEs with various carbon paper GDLs, developed in the lab, on the cathodic side. This study examined how properties like electrical conductivity, porosity, and gas permeability affect performance. These findings emphasize the need to optimize components beyond catalysts to improve the cost-effectiveness of hydrogen production through electrolysis.

Development of a magnetic rotator to enhance the hydrogen evolution reaction in a proton exchange membrane water electrolysis cell

In this study, a large-scale magnetic rotator for hydrogen production boosting was designed. The study addresses the challenge of selecting and designing mechanical components for a dynamic magnetic field (DMF) magnetic rotator in a green hydrogen electrolysis power plant, focusing on ensuring component reliability and efficiency under operational stresses. The aim is to determine suitable machine element materials (shaft, clutch, gears, etc.), allowable shear stress, and interconnection mechanisms through theoretical and practical evaluations. The method includes calculating the allowable shear stress for the spline based on carbon steel tensile strength, applying safety factors for material properties and load considerations, and determining shaft diameter using torque and shock load factors. Standard catalogs guide the selection of interconnections like clutches, gears, and bearings to ensure compatibility and performance. The results indicate that a 95 mm diameter S30C carbon steel shaft, with an allowable shear stress of 7.8 kg/mm2, meets the design requirements. The chosen spline dimensions and a 12.5 MW, 14-pole induction motor align with the system’s needs, ensuring reliable operation. The discussion highlights the critical balance between theoretical predictions and practical application in design optimization. It underscores the importance of incorporating safety factors and verifying component suitability to ensure robust performance of the magnetic rotator. This study provides a comprehensive approach to design optimization, integrating theoretical analysis with practical considerations to achieve optimal performance and reliability. The design output of this study can be used to boost the hydrogen evolution reaction in the SIEMENS Sylizer 300 electrolysis cell.