Large-scale Hydrogen Production Research Articles

Design and Optimization of Large-Scale Green Liquid Hydrogen Production Integrated with Heat Recovery and Absorption Precooling

Design and Optimization of Large-Scale Green Liquid Hydrogen Production Integrated with Heat Recovery and Absorption Precooling

Determination of hydrogen fuel production from GIS-based selected ponds using hybrid renewable energy systems in Kayseri

This study offers the feasibility study of large-scale hydrogen production to establish environmentally friendly hybrid energy facilities based on wind and solar energy resources in the vicinity of lakes and rivers within the Kayseri region of Türkiye. The ultimate objective is to enable hydrogen production from lakes and rivers and identify optimal locations for the installation of hydrogen fuel stations. The precise selection of locations for the designated province is based on geographical, environmental, and infrastructural considerations by utilizing GIS technology which allows spatial analysis and superimposition of various layers. The methodology also involves the utilization of the HOMER software to facilitate the integration of wind and solar power, along with hydrogen production, providing a platform for environmentally friendly energy system design and optimization. A comprehensive evaluation has been conducted for the sizing and placement of renewable energy systems based on microgrid analysis, the design of hydrogen production facilities, and the establishment of hydrogen refueling infrastructure. The study also incorporates a financial analysis to assess the economic viability of the project over its lifecycle. Among the five water sources considered, the highest annual hydrogen production is 830 tons in Zamantı River, while Kızılırmak River has the lowest value according to LCOE and LCOH values, 0.030 $/kWh and 3.85 $/kgH2, respectively.

In-situ exfoliating graphene to anchor Mo2C NPs and modulate crystal planes for hydrogen production

An economical and efficient noble metal-free catalyst is necessary for large-scale hydrogen production. Here, Mo2C nanoparticles (NPs) were well-dispersed on the surface of 2D graphene nanosheets by in-situ propping oxide graphene (GO) layers, anchoring molybdate ions between GO layers and pyrolysis. The exposed crystal planes were also adjusted by above strategy. The results indicate that uniform and well-dispersed Mo2C NPs with a narrow size distribution were anchored on 2D rGO nanosheets and exposed dual crystal planes. The results of hydrogen evolution reaction (HER) show that the optimal Mo2C/rGO catalyst only needs low overpotential (η10, 112 mV) to drive 10 mA cm−2 in alkaline solution, and η10 only increased by 12 mV after 1000 cycles test, indicating high activity and stability for HER. Notably, the overpotential is below than that of Pt/C commercial catalyst when current density is more than 100 mA cm−1. The excellent performance is benefit from low hydrogen adsorption Gibbs free energy (ΔGH∗) on the Mo2C catalyst. Therefore, the proposed strategy is efficient to prepare well-dispersed and dual crystal planes-exposed Mo2C NPs for electrocatalytic hydrogen evolution.

Evaluating the techno-economic potential of large-scale green hydrogen production via solar, wind, and hybrid energy systems utilizing PEM and alkaline electrolyzers

The study evaluates the potential of solar, wind, and hybrid PV/WT renewable energy systems for green hydrogen production in four Iraqi cities. Through a comparative analysis of six distinct scenarios involving the deployment of 60 MWp solar panels, 30 MWp wind turbines, and 45 MWp hybrid PV/WT systems, the research aims to ascertain the most energy-efficient and cost-effective strategy for hydrogen generation. This evaluation is aligned with the operational capacities of two types of water electrolyzers: Alkaline (AWE) and proton exchange membrane (PEM), each with a 17.5 MWp capacity. Employing the HOMER Pro software for system simulation and optimization, and considering a project timeline from 2022 to 2042, the study identifies Anbar City as the prime location for green hydrogen production, highlighting solar PV panels as the most economical option with the lowest levelized cost of energy at US $4.5/MWh. The analysis further demonstrates that hydrogen production costs are US $1.98/kg for AWE electrolyzers and US $2.72/kg for PEM electrolyzers, with net present costs of US $26.31 million and US $35.91 million, respectively. Moreover, the annual hydrogen output is estimated at 1.11 million kg for AWE and 1.19 million kg for PEM electrolyzers. These insights significantly contribute to the strategic planning and development of Iraqi green hydrogen sector, offering a valuable framework for policymakers and stakeholders invested in sustainable energy transitions.

Catalytic methane decomposition process on carbon-based catalyst under contactless induction heating

Hydrogen obtained from decomposition of natural gas with direct sequestration of carbon in solid form could be an attractive and cost-effective alternative for large-scale hydrogen production. We report here the use of a carbon-based catalyst to achieve the catalytic decomposition of methane (CMD) at medium temperature, 800 °C, under induction heating (IH). Analyses of the catalytic results and characterizations of the spent catalyst have shown that the carbon deposited during the reaction acts as the active phase for the reaction and can, therefore, be recycled infinitely. This autocatalytic effect can only be observed when the carbon catalyst operates under IH because the same catalyst operating under Joule heating (JH) deactivates rapidly in the same way as that already reported in the literature and no autocatalytic effect has been observed. The carbon formed is in the form of a graphene layer with a high degree of graphitization and is completely different from the carbon black powder obtained in other processes. These promising results could lay the groundwork for the development of an industrially and economically viable way to convert natural gas into turquoise hydrogen, using renewable energy and low-cost catalysts, with better resistance to poisoning by impurities present in the processing load. The combination of a carbon-based catalyst and non-contact IH could also lead to combined catalytic processes for many challenging reactions.

In situ fabrication of Ni3S2/Cu2S heterojunction on nickel foam as a highly efficient and durable electrocatalyst for overall water splitting

The development of cost-efficient bifunctional electrocatalysts is significant for overall water splitting. Herein, we report the in situ fabrication of heterogeneous NF/Ni3S2/Cu2S-X (where X refers to Cu2+ concentrations of 50, 75, and 100 mM) on nickel foam (NF) using an electrodeposition–hydrothermal method. The in situ electrodeposited metallic Cu0 layers on the NF conferred higher stability to the resulting bimetallic sulfide of Ni3S2/Cu2S. In alkaline media (1 M KOH), the optimized NF/Ni3S2/Cu2S-75 exhibited ultra-low overpotentials of 108 and 166 mV during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA·cm−2. For overall water splitting, the catalyst showed a significantly low cell voltage of 1.50 V and long stabilization time (≥150h)at15mA·cm−2. Density functional theory calculations revealed that the formation of Ni3S2/Cu2S heterojunction reduced the Gibbs free energy of hydrogen adsorption (ΔGH*) on the S site, thus facilitating H2 generation. This study serves as a guide for tailoring transition metal-based catalysts with enhanced activity and long-term durability, thereby contributing to highly efficient water electrolysis for large-scale hydrogen production.

Enhancement of electrocatalytic oxygen evolution performance for FeCrNiCoTi alloys via powder modification

The development of non-precious metal catalysts with excellent performance in the oxygen evolution reaction (OER) is crucial for large-scale and low-cost hydrogen production from water. FeCrNiCoTi multi-principal element alloy (MPEA), which is free of precious metals and possesses four specific effects, holds promise as a low-cost and efficient electrocatalyst for water electrolysis. However, further enhancing the exposure of its active sites remains a challenge. To address this issue, the FeCrNiCoTi MPEA powder was long-term mechanically milled to refine the grain size, introduce defects, and (oxygen) hydroxide species with the aim of improving OER catalytic performance. Such powder milled after 80 h exhibits an overpotential of 296 mV at 10 mA/cm2 and the Tafel slope of 41.3 mV/dec, with continuous stability for 40 h in 1.0 M KOH electrolyte, comparable to the commercial RuO2 catalyst. This work provides a simple, practical and effective approach for the preparation of high-performance, low-cost OER electrocatalysts.

Mega-scale solar-wind complementarity assessment for large-scale hydrogen production and storage (H2PS) in Algeria: A techno-economic analysis

Green hydrogen (GH2) is produced using renewable energy resources (RERs) such as solar photovoltaic (PV) and wind energy. However, relying solely on a single source, H2 production systems may encounter challenges due to the intermittent nature, time-of-day variability, and seasonal changes associated with these energies. This paper addresses the assessment of mega-scale solar-wind complementarity and the economic viability of large-scale H2 production and storage in Algeria, considering various climatic conditions. A techno-economic feasibility analysis is conducted by examining various factors, including resource complementarity, electricity and hydrogen productivity, solar and wind contributions, capacity factors (CFs), total net present cost (TNPC), the levelized cost of hydrogen (LCOH) production, and storage (LCOS). The findings reveal that among the studied locations (Tamanrasset, M'sila, Hassi R'mel, and Adrar), Tindouf ranked first in H2 production, with the highest amount at 11,267 kg and the lowest LCOH at 2.999 $/kg. Wind energy accounted for 69% (3,846,922 kWh) of the total (5,572,571 kWh), while solar energy contributed 31% (1,738,171 kWh). Economically, the LCOH-TNPC for the various locations ranged from 2.99 $/kg-77,042,696 $ to 3.70 $/kg-99,000,488 $. The total electricity-hydrogen generated is estimated at 25,840.251 MWh-529,395 kg. Wind power makes the major contribution, accounting for 63%–70%, compared to the PV system's share, ranging from 31% to 37%. Compared to relying on a single source, leveraging solar-wind complementarity presents opportunities for more consistent energy utilization and reliable hydrogen production. The obtained results are essential for decision-makers and policymakers in Algeria, indicating that the country can successfully achieve energy diversification and transition for future sustainability, and become a major player in the international hydrogen market.

Hydrogen production with a novel coaxial cylindrical electrolyser: A CFD study

This study introduces a unique coaxial cylindrical electrode design for Alkaline Water Electrolysers (AWEs) that is analyzed to show possible enhancements over the traditional stacked plate design. It investigates the performance of the proposed coaxial AWE for enhanced hydrogen production. Through comprehensive computational simulations, key performance indicators, such as current density and hydrogen volume fraction, are analyzed across various operating parameters. The results of this study indicate that the production rate of hydrogen achieves its highest level at a volume percentage of 3.4 %. This rate is significantly influenced by the concentration of the electrolyte, the distance between the cathode and anode rings, and, to a lesser degree, the porosity of the separator. Consequently, the optimized conditions demonstrate a promising increase in current densities, reaching 1000 mA/cm2 at an operating voltage of 2 V, showcasing the potential for developing more efficient and cost-effective AWE systems. This study further contributes valuable insights into the design and operational improvements needed for the advancement of large-scale hydrogen production technologies.

Ce-doped cobalt-based hydroxide assisted with low-temperature molten salt for industrial oxygen evolution reaction

Developing low cost and high-performance oxygen evolution electrocatalysts is significant to improve the efficiency of water electrolysis for large-scale hydrogen production. Cobalt hydroxide is a promising electrocatalyst for oxygen evolution reaction (OER), but its poor conductivity and activity seriously restrict the practical application. A simple one-step low temperature molten salt method was applied to successfully synthesize the Ce-doped cobalt hydroxide nitrate (Ce-CoNH/CF), which exhibits outstanding OER performance with a low overpotential of 448 mV at the current density of 1000 mA/cm2 in 1 mol/L KOH. The remarkable performance of Ce-CoNH/CF electrode in OER may be the comprehensive result of fast reaction kinetics, large electrochemical active specific surface area (ECSA) and small charge transfer resistance (Rct) as revealed by the Tafel, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) analysis. Under the simulated industrial test conditions (6 mol/L KOH, 70 °C), the Ce-CoNH/CF electrode still displays excellent OER performance.

Strong electron coupling effect of non-precious metal Schottky junctions enhanced square meter level photocatalytic hydrogen evolution

Photocatalytic hydrogen production technology utilizes solar energy to decompose water into hydrogen, helping to alleviate the pressure of energy depletion. Engineering of non-precious metal nanomaterials as cocatalysts can play a significant role in low-cost, sustainable, and large-scale photocatalytic hydrogen production. Herein, MnCdS-Vs/NiCo2S4 (MCSN) Schottky junction nanomaterials with strong electron coupling effect were prepared by a two-step hydrothermal method and successfully applied to a square meter hydrogen evolution device. The optimized MCSN material demonstrated high hydrogen evolution activity of 34.28 mmol g−1 h−1, which is 9.34 and 685.60 times higher than that of pure MnCdS-Vs and NiCo2S4, respectively. More importantly, in a square meter (1 m2) flat-plate reactor, MCSN produced H2 evolution approximately 201 mmol in 5 h, showcasing its potential for large-scale applications. In-situ XPS and DFT calculations demonstrated that MnCdS-Vs interacts with NiCo2S4 to produce a strong electron coupling effect and form a Schottky junction. It promotes the facilitated the directional migration of photogenerated electrons from MnCdS-Vs to NiCo2S4, but also effectively suppressed electron backflow through the Schottky barrier. Furthermore, the abundance of sulfur vacancies enhanced visible light absorption capability, further improving photocatalytic hydrogen evolution performance. This work delves into the role of defect engineering and Schottky junction design in enhancing photocatalytic performance, providing new insights into transitioning photocatalytic hydrogen production technologies from small-scale laboratory experiments to large-scale practical applications.

Optimization of hydrogen production in multi-Electrolyzer systems: A novel control strategy for enhanced renewable energy utilization and Electrolyzer lifespan

In large-scale water electrolytic hydrogen production system based on renewable energy, the allocation strategy of hydrogen production power among multi-electrolyzers plays a critical role in the efficiency of renewable energy utilization and the quantity of hydrogen production, given a fixed power output from renewable energy sources. This paper considers the minimum hydrogen production power constraint of electrolyzer and proposes a novel control strategy for multi-electrolyzers. The operational phase of multi-electrolyzers is divided into two distinct phases: 1) the rapid start-up phase; 2) the equal power allocation phase. During the rapid start-up phase, by reducing the power of electrolyzer that has reached its rated power to a predetermined level and using this saved power to start another electrolyzer, this strategy ensures that electrolyzers can proactively and quickly exceed the minimum operational power threshold. Upon the activation of all electrolyzers, the system enters second phase, wherein the power is evenly allocated among all electrolyzers. Besides, this strategy employs a priority scheduling method to ensure the uniformity of operating times across all electrolyzers. Compared to the existing three control strategies, this proposed strategy demonstrates significant advantages in minimizing unused wind energy and optimizing the lifespan of electrolyzers. The effectiveness of proposed strategy is validated by the simulation result.

A3B Zn(II)-Porphyrin-Coated Carbon Electrodes Obtained Using Different Procedures and Tested for Water Electrolysis

In the context of water electrolysis being highlighted as a promising technology for the large-scale sustainable production of hydrogen, the water-splitting electrocatalytic properties of an asymmetrically functionalized A3B zinc metalated porphyrin, namely, Zn(II) 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin, were evaluated in a wide pH range. Two different electrode manufacturing procedures were employed to outline the porphyrin’s applicative potential for the O2 and H2 evolution reactions (OER and HER). The electrode, manufactured by coating the catalyst on a graphite support from a dimethylsulfoxide solution, displayed electrocatalytic activity for the OER in an acidic electrolyte. An overpotential value of 0.44 V (at i = 10 mA/cm2) and a Tafel slope of 0.135 V/dec were obtained. The modified electrode that resulted from applying a Zn(II)-porphyrin-containing catalyst ink onto the same substrate type was identified as a bifunctional water-splitting catalyst in a neutral medium. OER and HER overpotentials of 0.78 and 1.02 V and Tafel slopes of 0.39 and 0.249 V/dec were determined. This is the first Zn(II)-porphyrin to be reported as a heterogenous bifunctional water-splitting electrocatalyst in neutral aqueous electrolyte solution and is one of very few porphyrins behaving as such. The TEM analysis of the porphyrin’s self-assembly behavior revealed a wide variety of architectures.

Bifunctional Noble-Metal Free Ternary Chalcogenide Electrocatalysts for Water Splitting

With the ever-increasing global energy demand, the development of renewable energy technologies is crucial to fulfilling the energy requirements in a sustainable manner. Hydrogen has emerged as a promising energy carrier that can provide emission-free energy for end-use applications. Among the several pathways of hydrogen production, green hydrogen production by electrochemical water splitting using renewable energy is an emission-free, efficient energy conversion technology. Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) occur at the cathode and anode, respectively. Water splits into hydrogen and oxygen at the thermodynamic potential of 1.23 V; however, overpotentials are observed experimentally due to the kinetic barriers, which increases the required potential for water splitting. Catalysts lower the required overpotentials, making the process more energy efficient. A significant issue with large-scale hydrogen production by water electrolysis is that the state-of-the-art catalysts for HER and OER are based on precious metals and thus are limited by their high cost and net production capacity. Thus, there is a lot of interest in developing noble-metal-free electrocatalysts based on earth-abundant materials that can efficiently lower the associated overpotentials for the two halves of the water-splitting reaction.A large number of late transition metal-based ternary complex oxides have been investigated for their catalytic performance towards water splitting, where fine-tuning of the properties using compositional engineering has been demonstrated. Binary sulfides, selenides, and phosphides have also been explored as candidates for water splitting. Recently, early transition metal-based ternary complex materials have emerged as a novel class of electronic materials with applications in infrared optics and photovoltaics. However, similar chalcogenide compositions based on late-transition metals remain underexplored.We have synthesized a series of LaMS3 (M = Mn, Fe, Co, Ni) materials by high-temperature sulfurization of corresponding ternary oxides, using carbon disulfide (CS2) as the sulfurizing agent. The LaMS3 compounds are isostructural and crystallize in the hexagonal P 63 space group. When tested for catalytic performance towards water splitting, they demonstrate good activity towards both HER and OER, with LaNiS3 (LNS) being the most active material, and a periodic activity trend is observed, where LNS > LCS >> LFS > LMS. For OER in alkaline electrolyte, LNS demonstrates an overpotential of 373 mV at 10mA/cm2 in 1.0 M KOH, and a low Tafel slope value of 48 mV/dec. The long-term stability was tested using chronopotentiometry measurements, and LNS shows excellent stability, with negligible change in overpotential over several hours. For HER testing in both acidic and alkaline electrolyte, LNS again seems to be the most active material, and a periodic activity trend in the HER activity of LaMS3 materials, similar to the OER activity trend, is observed. LNS has an overpotential of 340 mV in 0.5 M H2SO4 and 362 mV in 1.0 M KOH, indicating that LNS is catalytically active over a wide range of pH levels. LNS also shows excellent long-term stability towards HER in both acidic and alkaline electrolyte. We also compared the activity of LaMS3 materials with their ternary oxide counterparts from which they were synthesized, and the LaMS3 compounds outperform the LaMO3 compounds, demonstrating lower overpotentials and Tafel slope values for both HER and OER, with the HER overpotentials for LaMO3 materials being > 250 mV higher compared to LaMS3, for both acidic and alkaline electrolytes. The catalytic activity of the LaMS3 series towards both HER and OER, along with their excellent long-term stability, makes these materials promising candidates for bifunctional electrocatalysts for water splitting while offering a wide compositional range that allows for further optimization of their performance.

The Effect of Cation Contamination on the Water Transport for PEM Water Electrolysis

Large-scale hydrogen production by PEM water electrolysis (PEMWE) in the energy sector requires a deep understanding of the system behaviour in failure cases and possible recovery procedures. This includes the purification of the anolyte feed water because the contamination with ions can cause the PEMWE stack to breakdown.[1] For instance, the presence of iron trace cations or other metal cations in the feed water leads to a performance loss due to higher ohmic resistance of the cell and higher iR-free voltages.[2] [3] Moreover, cation contamination might influence the water transport in a PEMWE cell. In principle, the transfer of the water molecules to the cathode is proportional to the proton flux from the cathode to the anode. The proportionality factor is defined as water transport coefficient and is also temperature dependent.[4] In case of the mono- and multivalent cations as trace elements in the feed water, the water loading of the membrane, which is expressed by water molecules per sulfonic acid group of the membrane, λ, decreases over time and leads to successive increase in the ohmic resistance. [5] However, the influence of cation contamination on the water transport in PEMWE is poorly understood to date.In this work, we investigated the effect of cation contamination in the anode feed water on the water crossover for PEMWE. Cation contamination experiments were carried out at a constant current density by adding different concentrations such as K2SO4, Na2SO4, etc. to the anode feed water. All electrochemical measurements were carried out in an in-house test bench equipped with a single cell of 5 cm2 geometric electrode area and potentiostat with booster. A commercially available catalyst coated perfluorosulfonic acid membranes (loading of 0.3 mg cm-2 geo Pt/C and 1 mgcm-2 geo IrOx) was used. The anode and cathode compartments were kept at atmospheric pressure and cell temperature of 80°C. To determine the water crossover from anode to cathode at different current densities, the cathode exhaust was cooled in a heat exchanger and measured by a gravimetric method. [4] Firstly, a conditioning procedure was performed with purified feed water until steady cell performance was achieved. The cell performance was evaluated using polarization curves, electrochemical impedance spectroscopy (EIS) and water crossover measurements. The last two are of particular interest, because they provide information about membrane humidification. The Tafel slope and mass transport overvoltage were established from the polarization curves and high frequency resistance (HFR). We observed a significant rise of the cell voltage by adding cations to the anode water feed within few hours. The analysis of Tafel slope and EIS data also reveal an increase of ohmic and mass transport resistances. In these experiments, we were able to correlate the HFR results with the water crossover as a function of the nature of the cation and its concentrations. Our data shows that the specific water crossover per current density decreases as a consequence of cation contamination. The switch back to purified feed water allows us to monitor the dynamics of the performance recovery process obtained from EIS and water crossover measurements. Additional measurements of the polarization curves and HFR were used to distinguish between reversible and irreversible degradation processes due to the cation contamination.Altogether, we present the effect of cation contamination on the water transport processes and provide deeper insights into the mass transport and performance losses for PEMWE.

(Invited) The U.S. Department of Energy’s Hydrogen Consortium for Advanced Water Splitting Materials

The goals of the Hydrogen and Fuel Cell Technologies Office (HFTO) support those of the Biden Administration to build a clean and equitable energy economy and address the climate crisis through development and deployment of hydrogen technologies to the benefit of all Americans. HFTO is dedicated to meeting the goals of DOE’s Hydrogen Shot,1 which targets affordable clean hydrogen production at $1/kg within the decade, and the H2@Scale Initiative,2 which aims to advance affordable hydrogen to enable decarbonization and revenue opportunities across multiple sectors.HFTO’s HydroGEN consortium (https://www.h2awsm.org) for advanced water splitting (AWS) materials, part of the DOE’s Energy Materials Network (EMN), focuses on multiple clean hydrogen production pathways, including several relevant to renewable fuels via artificial photosynthesis. Since the consortium’s establishment in 2016, HydroGEN researchers have made significant progress in the areas of low and high temperature electrolysis, as well as solar thermochemical (STCH), and most relevant here, photoelectrochemical (PEC) hydrogen production pathways. The HydroGEN consortium facilitates collaborations between national laboratories, academia, and industry, bringing together world-class technical expertise with state-of-the-art facilities made available to project partners. HydroGEN offers an extensive collection of materials research capabilities for addressing R&D challenges. Project participants can choose from over 40 unique capability nodes. Each capability node is comprised of a combination of a tool, technique, and expertise that is unique to the national laboratory system.HydroGEN has supported over 30 competitively selected R&D projects with industry and academic partners by providing streamlined access to national lab resources and expertise. The consortium is also involved in fostering cross-cutting activities to advance material performance and durability through community engagement and protocol development and initiating critical laboratory-led efforts to address specific R&D gaps in the AWS portfolio.A new cohort of solar fuels focused projects were recently selected through the Funding Opportunity Announcement (FOA) Number: DE-FOA-0002792 with additional funding in this area expected in the future. A total of 11 new projects were selected, six in PEC and five in STCH, to work with the HydroGEN consortium towards advancing solar fuels production technology. Projects from both technology pathways must define materials metrics and targets for meeting the interim hydrogen cost target of $2/kg-H2 with extrapolation to additional requirements for meeting $1/kg-H2.Selected PEC projects focused on the development of materials or material systems for efficient and durable PEC water-splitting with a focus on innovations in bandgap and bandgap alignment, functional interfaces, stable surface catalysis, and protective coatings. A successful PEC photoelectrode project will need to achieve 15% STH efficiency for the entirety of operation exceeding 1,000 hours, with proposed pathways for achieving efficiencies up to 25% and durability up to 10,000 hours. Further, PEC systems will be required to demonstrate hydrogen production at a rate of 0.1 g/h for diurnal operation over two weeks.Selected STCH projects focused on accelerating discovery, development, and demonstration of alternative redox materials for a two-step STCH process and addressing projected costs and materials challenges associated with the required operating temperatures. Successful STCH projects will need to include a demonstration of the STCH process using sunlight or simulated sunlight. STCH systems must demonstrate hydrogen production at a rate of 1 g/h for diurnal operation over two weeks.For the first time, in line with the Justice40 Initiative,3 applicants were required to submit DEIA (diversity equity, inclusion, and accessibility) plans. Objectives from these plans were incorporated into the project objectives with specific goals identified for each year.Despite the progress, there is still significant ground to be covered through water splitting materials R&D. With the support of HydroGEN, these selected projects will help to address remaining challenges and enable low-cost and large-scale hydrogen production. An overview of consortium and project goals and objectives will be discussed. Hydrogen Shot | Department of EnergyH2@Scale | Department of Energy,The Justice40 initiative, created by Executive Order 14008, establishes a goal that 40% of the overall benefits of certain federal investments flow to disadvantaged communities. Figure 1

Approaching the Multiphase Interface of Ir-Based PEM Electrolyzers Using Operando ‘Tender’ X-Ray AP-XPS

Electrochemical water splitting is a promising pathway for the renewable production of hydrogen as an alternative fuel and chemical feedstock. Yet, the process is plagued by slow kinetics of the essential oxygen evolution reaction at the anode. Further, large-scale hydrogen production from such devices will require reduced platinum group metal (PGM) loadings (often iridium-based anodes) and/or new materials due to factors such as PGM scarcity, cost and loss during operation. In the hopes of enabling progress of rational design for OER catalysts, effective characterization of the electrode-liquid interface is crucial. Synchrotron-based X-ray Photoelectron Spectroscopy (XPS) offers a versatile way to obtain surface chemical and elemental characterization of these materials. The use of X-rays in the ‘tender’ regime (~2-6 keV) allows for deeper probing than the conventional ‘soft’ x-ray (< 2000 eV) set up that is common at synchrotrons and lab-based sources. The photoelectrons generated from tender x-rays have enough energy to penetrate tens of nanometers through low density components such as a layer of liquid or polymeric electrolyte. This opens the door to access the chemistry at the interface of liquid and ionomer electrolyte-electrocatalyst materials. With the use of a fully operational two-electrode system, we are able to study these membrane electrode assemblies under active water splitting conditions.My talk will explain our specific approach, which is often crucial for successful collection of accurate data, highlighting elements of cell design and experimental setup that are helpful for this process. I will also show recent AP-XPS results on iridium-based polymer electrolyte membranes for water splitting. With application of elevated potential, we can correlate the iridium valency and surface species with the appearance of product traces in a mass spectrum. Figure 1

3D-Printed Hierarchical Electrodes for Ampere-Level Alkaline Water Electrolysis

In the realm of water electrolysis technology, Alkaline Electrolysis Cell (ALK) hydrogen production stands as a pivotal technology, playing a critical role in the pursuit of large-scale green hydrogen production and the achievement of the "dual carbon" objective. Despite its importance, the mass transfer efficiency of commercial porous nickel electrodes currently used in ALK systems is suboptimal. These electrodes, plagued by unstable catalyst loading, typically operate at current densities between 300-500 mA/cm², seldom reaching the desired threshold of 1 A/cm². This limitation hampers the potential of ALK hydrogen production to satisfy industrial-scale hydrogen production demands.In the quest to overcome these limitations, the concept of the Triple Periodic Minimum Surface (TPMS) structure, a cellular architecture mathematically defined and prevalent in natural biological forms such as butterfly wings and beetle shells, is introduced. The TPMS's unique geometry is adept at adapting to mechanical requirements for various applications, including structural and fluidic systems. It allows for versatile manipulation of geometric parameters like aperture size, porosity, and tortuosity, thereby substantially broadening the design possibilities for electrode structures and enhancing the efficiency of gas-liquid and electron transfer.To harness these benefits, we propose the creation of nickel/nickel-iron electrodes using 3D printing technology. These electrodes are characterized by their cross-scale porosity, ordered structure, and adjustable TPMS design. This innovative electrode design significantly augments bubble transport efficiency and mass transfer performance, while also providing additional anchor points for catalysts, thereby enhancing the electrochemical active surface area, intrinsic activity, and stability of the composite catalyst. As a result, these electrodes achieve ampere-level current densities in ALK electrolysis cells, enhancing electrolysis efficiency and reducing energy consumption.Our methodology involves the use of selective laser melting printing technology to fabricate multi-tier nickel/nickel-iron electrodes of varying specifications. These electrodes are then coated with MOOH catalysts using an electrochemical deposition process. Through rigorous testing and comparison of electrochemical performance parameters, we identified the optimal multi-stage nickel/nickel-iron electrode and its composite catalyst.Electrochemical performance tests reveal that, compared to traditional commercial porous nickel electrodes, our 3D printed electrodes decrease overpotential by 14% and improve electrolytic cell efficiency by 10% at a current density of 1 A/cm². Furthermore, these electrodes exhibit minimal degradation after a 500-hour durability test. The demonstrated efficiency and durability of these 3D-printed hierarchical electrodes indicate significant potential for their application in ampere-level alkaline water electrolysis. Figure 1

Pegylated Viologen Derivatives to Improve Performance of Aqueous Organic Redox Flow Battery

Renewable energy sources like wind and solar power are great alternatives for a clean way to produce electricity but have the inconvenience to fluctuate1. To address this issue and promote the implementation of renewables sources, scientists are developing new ways to store energy while production is at a maximum for a subsequent release when there is demand. Redox flow batteries (RFBs) are the most appropriate solution and are increasingly gaining attention for stationary, large scale electrochemical energy storage2,3. One variation of RFBs are aqueous organic redox flow batteries (AORFBs), where water-soluble organic molecules are use as the redox couple. Viologen type molecules are particularly well-suited as a negative potential species to develop cheaper and better AORFBs with great scalability, reversibility and long-term stability4.In this study, viologen derivatives were synthesized with various N-functional groups to explore the impact of the substituent on their solubility, viscosity and redox potential. We showed that the use of short chains of poly(ethylene glycol) improved the solubility of the viologens derivatives which could lead to batteries with higher capacity. The symmetric viologen (with two identical substituents) provided a great solubility in water and the formal potential was unaffected by the chemical nature of the substituents. We demonstrated that the 1,1’-(bisethylene glycol)-4,4’-bipyridium (PEG2-V-PEG2) showed the most promising properties with a high solubility (2.3 M in 1M KCl) and low viscosity (3.01 mPa*s at 1M). As such, this derivative was selected for further evaluation in an asymmetrical labs-scale RFB prototype cell versus bis(trimethylamoniumpropyl)ferrocene (BTMAP-Fc). The compound was studied at various concentrations to assess the maximum energy density that can be reached and the effect of concentration on cycling life by achieving a comparison to the symmetrical 1,1’-bis(3-sulfonatopropyl)-4,4’-bipyridium (SPr-V-SPr) at 0.5 M. Figure 1: Redox flow battery scheme using Viologen derivative as the negolyte and BTMAP-Fc as the posolyte Reference Shi, X., Qian, Y. and Yang, S. Fluctuation analysis of a complementary wind–solar energy system and integration for large scale hydrogen production. ACS Sustainable Chemistry & Engineering, 8(18), pp.7097-7110. (2020)Sánchez-Díez, E.; Ventosa, E.; Guarnieri, M.; Trovò, A.; Flox, C.; Marcilla, R.; Soavi, F.;Mazur, P.; Aranzabe, E.; Ferret, R., Redox flow batteries: Status and perspective towards sustainable stationary energy storage. Journal of Power Sources, 481, 1-23. (2021)Poullikkas, A., A comparative overview of large-scale battery systems for electricity storage. Renewable and Sustainable energy reviews, 27, pp.778-788. (2013)Gentil, S., Reynard, D. and Girault, H.H. Aqueous organic and redox-mediated redox flow batteries: a review. Current Opinion in Electrochemistry, 21, pp.7-13. (2020) Figure 1

Limitations and Opportunities of Self-Supported Co-Based Anodes for Pure Water-Fed Anion Exchange Membrane Water Electrolyzers

Hydrogen has been regarded as an energy source with a potential to be used in various sectors, including transportation, power generation and industrial processes1-3. Producing hydrogen via water electrolysis using green electricity will be necessary for a sustainable future. Proton exchange membrane water electrolysis (PEMWE) is one of mature and leading electrolysis technologies, while anion exchange membrane water electrolysis (AEMWE) is regarded as a new, emerging technology4. However, PEMWE system suffers from their expensive cost and scarcity of iridium-based oxygen evolution reaction (OER) catalysts, having no alternative OER catalysts. Compared to PEMWE, AEMWE can be pursued with non-platinum group metal (non-PGM) thanks to its alkaline environment4,5.Here, non-PGM Co-based catalyst coated anodes were prepared using a simple hydrothermal reaction followed by heat treatment. Different phases and crystallinity of cobalt-based anodes were prepared and tested in pure water-fed AEMWE devices. To investigate the catalyst-ionomer/membrane interfaces at the anodes, the loadings of Co3O4 catalyst and ionomer topcoats were controlled. The cell performance in polarization curves was correlated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. The comparison of anodes operated with pure water feed and with supporting electrolyte was made to highlight the importance of catalyst-ionomer interface in pure water-fed AEMWE. Lastly, our self-supported Co3O4 anode outperformed a commercial Co3O4 NP ink-based anode, projecting a potential of direct growth of catalyst materials on PTLs in pure water-fed AEMWE.Reference(1) Agyekum, E. B.; Nutakor, C.; Agwa, A. M.; Kamel, S. A Critical Review of Renewable Hydrogen Production Methods: Factors Affecting Their Scale-Up and Its Role in Future Energy Generation. Membranes 2022, 12 (2).(2) Qusay, H.; Sameer, A.; Aws Zuhair, S.; Hayder, M. S.; Marek, J. Green hydrogen: A pathway to a sustainable energy future. Int. J. Hydrogen Energy 2024, 50, 310-333.(3) Joonsik, H.; Krisha, M.; HeeJin, C. A review of hydrogen utilization in power generation and transportation sectors: Achievements and future challenges. Int. J. Hydrogen Energy 2023, 48 (74), 28629-28648.(4) Lee, S. A.; Kim, J.; Kwon, K. C.; Park, S. H.; Jang, H. W. Anion exchange membrane water electrolysis for sustainable large-scale hydrogen production. Carbon Neutralization 2022, 1 (1), 26-48.(5) Juchan, Y.; Myeong Je, J.; Xiaojun, Z.; Yoo Sei, P.; Jooyoung, L.; Sung Mook, C.; Yadong, Y. Non-precious electrocatalysts for oxygen evolution reaction in anion exchange membrane water electrolysis: A mini review. Electrochem. Commun. 2021, 131, 107118.