bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracking the Evolving Structure of Nickel–Iron Oxyhydroxide Oxygen Evolution Electrocatalysts in Alkaline Media
Authors: Cullen David A. , Yu Haoran , Hermann Raphael P. , Lyu Xiang , Serov Alexey , Osmieri Luigi , Zelenay Piotr , Park Jaehyung , Kropf A. Jeremy , Sweers Matthew , Myers Deborah J. , Kreider Melissa E , Alia Shaun M , Mizrahi Michael , Elbaz Lior 
Published: December 2024

Anion exchange membrane water electrolyzers (AEMWEs) present a lower cost option for hydrogen generation with respect to their proton exchange membrane counterpart due to the possibility of utilizing platinum group metal-free catalysts to drive the oxygen evolution reaction (OER) at the anode. The addition of iron (Fe) to nickel-(oxy)hydroxides has been shown to significantly enhance the OER catalytic activity, although the precise mechanisms are still under debate. A clearer picture of the structure of these catalysts, particularly during operation, is needed in order to further improve their performance and durability.
In this work, a range of in situ and ex situ characterization techniques are used to study NiFe-based OER catalysts synthesized via different approaches [1]. High resolution electron microscopy will be presented showing how the as-synthesized structure of these materials transforms dramatically following break-in and initial performance evaluation [2]. The results of complementary in situ Mössbauer and X-ray absorption spectroscopy experiments which track the changing oxidation states of Fe and Ni under applied potential in aqueous media will also be presented. The structural changes related to catalyst degradation following extended operation in membrane electrode assemblies will also be discussed.

References

[1] W. Moschkowitsch et al., Nanoscale, 14 (2022) 18033-18040
[2] L. Osmieri et al., Applied Catalysis B: Environment and Energy 348 (2024) 123843
Metal-Organic Framework-Derived PGM-Free Electrocatalysts for Hydrogen Evolution Reaction in Alkaline Media
Authors: Zhang Hanguang , Zelenay Piotr 
Published: December 2024

Nickel (Ni)-based materials are among the most promising platinum group metal-free (PGM-free) electrocatalysts for hydrogen evolution reaction (HER) in alkaline media. With the growing demand for green hydrogen production, the HER activity of Ni-based catalysts must be enhanced to meet the goal of low-cost and sustainable hydrogen production.1 Carbon-supported Ni-based catalysts are typically prepared through the heat-treatment of Ni-based precursors with carbon supports.2 However, the catalysts obtained by this approach suffer from high content of inactive carbon and a non-uniform distribution of Ni-based nanoparticles, leading to low HER activity. These issues amplify the need for novel Ni-based catalysts with a well-controlled catalyst structure designed for maximizing catalyst utilization and minimizing electrode thickness.
In this talk, we will present our recent progress in developing Ni-based HER catalysts derived from metal-organic framework (MOF) precursors. Taking advantage of the characteristics of well-defined structure, high porosity, and flexible chemistry of MOF precursors3, the MOF-derived catalysts exhibit very promising activity towards HER allowing to reach 10 mA/cm2 at an overpotential of less than 100 mV in alkaline media. We will discuss how the ligand in MOF precursors and heat treatment conditions influence the structure and HER performance of Ni-based catalysts. This understanding promises to provide much needed guidance for the advancement of Ni-based catalysts for HER in alkaline media.

Acknowledgement

This work has been partially supported by the Center for Alkaline Based Energy Solutions (CABES) funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award DE-SC0019445.

References:

DOE Energy Earthshots Initiative: Hydrogen Shot. U.S. Department of Energy, 2021. https://www.energy.gov/eere/fuelcells/hydrogen-shot.

Jang, M. J.; Yang, J.; Jeong, J.; Kim, G. H.; Kwon, C. Y.; Myung, N. V.; Lee, K. H.; Choi, S. M. ACS Sustain. Chem. Eng.
2021, 9, 12508.

Zhou, H.-C.; Long, J. R.; Yaghi, O. M. Chem. Rev.
2012, 112, 673.
Operando XPS Study of Tungsten Oxide-Supported Iridium Nanoparticles: High-Efficiency Water Splitting Catalysts in Acidic Environments and PEM Electrolysis
Authors: Chueh Lu Yu , Hsu Yu Wei , Wu Chang-Ming , Tsai Meng-Hsuan , Yang Chueh-Cheng , Wang Chia-Hsin , Pan Yung-Tin 
Published: December 2024

In the quest for sustainable energy solutions, our recent submission targets a critical challenge in the realm of hydrogen energy production, specifically within Proton Exchange Membrane Water Electrolysis (PEMWE) systems. The overarching goal is to reduce the reliance on iridium (Ir), a scarce and expensive material, thereby enhancing the economic feasibility and sustainability of hydrogen production.
To achieve this, we have refined our synthesis approach, focusing on the dispersion of Ir within tungsten oxide supported Ir nanoparticles (NPs). A comparative analysis of different solvents (organic versus aqueous) and concentrations revealed that aqueous solutions at lower concentrations offer superior catalyst dispersion and a higher loading of iridium. This outcome is pivotal for creating a continuous conductive layer essential for PEMWE applications, where the efficiency of water electrolysis can be significantly impacted by the catalyst's performance.
Our innovations have led to a substantial increase in activity under acidic conditions, as evidenced by Rotating Disk Electrode (RDE) testing. Here, we achieved a performance enhancement of 3.2 times at 1.55V compared to Iridium Black, and remarkably, over 30 times when juxtaposed with crystalline Iridium Oxide. Such advancements underscore the potential for considerable efficiency improvements in hydrogen production.
Our prior investigations, through Synchrotron-based X-ray Photoelectron Spectroscopy (XPS) has provided insights into the electron donation capabilities of Tungsten Oxide during the Oxygen Evolution Reaction (OER) process. This electron donation boosts the electron density on iridium, thereby amplifying its catalytic activity and mitigating over-oxidation risks.
Our investigation also extended to operando-Synchrotron-based XPS analyses of in-situ acidic electrolysis reactions under catalyst-coated membranes. Notably, at low iridium loadings, we observed that Iridium Black is prone to over-oxidation and activity loss at voltages exceeding 1.7 V (vs. RHE), a challenge not faced by tungsten oxide supported Ir, which demonstrated stable performance signals and avoided current density degradation at higher voltages.
By successfully implementing this advanced material in PEMWE applications, we have made significant strides towards achieving high efficiency with low Ir loading. This breakthrough not only enhances the economic viability of hydrogen energy production but also contributes to the broader adoption of green energy solutions, marking a significant advancement in the pursuit of sustainable and efficient membrane electrode assemblies for hydrogen production.
Spatial Atomic Layer Deposition to Manufacture Catalyst Coated Electrodes for PEM Water Electrolysis with Ultra-Low Loadings of Iridium
Authors: Diaz-Morales Oscar , Shen Jie , Sidney Santana Cássia , Bens Frennie , Dijk Bas 
Published: December 2024

Proton Exchange Membrane Water Electrolysis (PEMWE) has great potential to produce hydrogen with renewable energy sources (green hydrogen production) because the technology can operate at high-power density with rapid startup times. However, PEMWE relies on scarce materials. Iridium usage as catalyst in PEMWE is a major point of attention because this metal is the second scarcest in our planet. State-of-art PEM electrolysers use approximately 2.5 g of iridium per kilowatt of power, this would translate in requiring >100% of the yearly global iridium production to sustain green hydrogen production at the multi-gigawatt power level [1]. Therefore, it is key to reduce the usage of iridium in PEMWE and to manufacture components to ease up recyclability upon reaching end of life.
In this work, we show our advances in manufacturing anodes for PEMWE with (ultra-)low loadings of iridium. The anodes were made by depositing iridium thin films on porous transport layers (catalyst coated electrode, CCE) by Spatial Atomic Layer Deposition (sALD) [2]. This manufacturing approach allows atomic level control over the amount of material deposited and it ensures high uniformity and conformality of the deposited films. By manufacturing CCEs with sALD, we reduced the amount of iridium used in the PEM electrolysis more than 100 times compared to the state of the art. Importantly, we found that the structure of the porous substrate, the manufacturing process and the usage of protection coatings are crucial to get good performance and enhance the durability of CCEs in PEMWE (see Figure 1).
Our work showcases the potential of using sALD to produce high performing and durable PEMWE electrodes. This manufacturing approach can minimize the usage of iridium in PEM electrolysers and has the high throughput needed to fulfill the demand for components that will come along with the multi-gigawatt electrolysers deployment envisioned in the near future. Furthermore, the usage of CCE in PEMWE separates the inorganic components of the electrolyser (i.e. catalyst layer and porous transport layer) from the organic part (i.e. proton exchange membrane), which will make it easier to recycle PEMWE components.

References

[1] Gavrilova, A., Wieclawska, S.M. “Towards a green future. Part 2” (2021). TNO report 21-12158.
[2] Shirvanian, A. P. Thin film porous catalyst sheet, WO 2023287284 A1, 19 January 2023.

Figure 1
Doped Rutile TiO2 Nanowires As Supports for Durable Proton Exchange Membrane Water Electrolyzers
Authors: Murphy Eamonn , Li Kui , Diaz-Abad Sergio , Komini Babu Siddharth , Wang Xiaojing , Spendelow Jacob S. 
Published: December 2024

Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology to achieve green hydrogen. Currently, PEMWE cost is dominated by the high loadings of ultra-scarce Ir-based catalysts, which remains the only metal that demonstrates a promising balance of activity and durability for the oxygen evolution reaction (OER), the limiting reaction of PEMWEs.1 Aimed at improving the activity and durability, current PEMWEs use high Ir loadings up to several mgIr cm-2. The high Ir loadings provide a pathway for electronic transport through particle-particle contacts, while yielding a thicker catalyst layer to maintain electronic conductivity as the nanoparticles degrade through operation. The DOE Hydrogen Earthshot aims to reduce the cost of green hydrogen by 80%. To realize this ambitious goal, Ir loadings must be significantly reduced, while maintaining conductivity and durability, which remains a major challenge.
In this study, we demonstrate the effectiveness of stable, conductive, Nb-doped rutile TiO2 (Nb-TiO2) nanowires as supports, for durable PEMWEs at low Ir loadings. The Nb-TiO2 nanowires provide an enhanced electron transport pathway through a 1-D morphology, reducing particle-particle contact resistances. Through a photodeposition-based approach2, a continuous layer of IrOx nanoparticles is formed on the surface of the Nb-TiO2 nanowire. The activity of the IrOx/Nb-TiO2 nanowire is evaluated in both a rotating disk electrode and PEMWE configuration, outperforming an unsupported commercial IrOx catalyst. Accelerated stress tests cycling between 2.0 V and 1.45 V holds over 300 hours, show the superior durability of the IrOx/Nb-TiO2 nanowire catalyst at a low Ir loading of 0.12 mgIr cm-2
, compared to the commercial IrOx catalyst. Our results demonstrate a promising platform to achieve highly active and durable Ir-based catalysts in practical PEMWEs at low Ir loadings.

Acknowledgement

This research is supported by the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) (20240061DR) and US Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office (HFTO).

References:

[1] Thao, Nguyen Thi Thu, et al. Small Science 4.1 (2024): 2300109.
[2] Hoffmeister, Darius, et al. ChemRxiv. (2024)
Advanced Nano-Porous Thin Films: Automating Water Electrolysis with Spark Ablation Printing
Authors: Irtem Erdem , Arici Ece , Asperti Simone , Schouten Niels , Van Vugt Aaike 
Published: December 2024

The current commercial loading of Platinum grade materials (PGMs) per membrane electrode assembly (MEA) stands at 2 mg/cm2, necessitating significant efforts to redesign electrocatalyst materials through a nano-architecture approach, requiring a thousandfold increase in surface area (from µm to nm scale) and a tenfold reduction in mass loading (from mg to µg). This objective can be realized through innovative surface engineering and manufacturing techniques as traditional wet synthesis methods pose several steps leading to spot errors (during ink formulation and coating) and high manufacturing costs (during drying steps) hampering scale-up efforts especially for low PGM loading < 0.5 mg/cm2 in PEM-WE.
VSPARTICLE developed a nano-printing technology utilizing spark ablation. This dry-synthesis method generates nanoparticle films only by using metal rods and electricity, and immobilize nano-porous electrocatalyst thin films on any substrate. In this presentation, we will unveil the latest findings concerning oxygen evolution reaction (OER) electrodes employing Ir-based and Ni-based catalysts produced through the innovative VSP-P1 nano-printing technology. The MEAs prepared using spark ablation had significantly lower loading (e.g., 0.1 and 0.4 mg/cm2) than the commercial state-of-the-art without compromising performance. The study integrates comprehensive flow-cell experiments, meticulous control tests, and characterization techniques on proxy samples, leveraging the versatility of VSP-P1 to create identical nano-porous films on various substrates. The scalability of this dry manufacturing process, coupled with rapid iteration capability for tuning material parameters and test-beds, promises a tenfold acceleration in electrocatalyst utilization.
In conclusion, this presentation unveils an efficient strategy for catalyst utilization through nano-printed layers, significantly reducing the time required to bring novel materials to market. The methodology outlined herein holds great promise for advancing hydrogen deployment and sustainable transitions in hard-to-decarbonize sectors.

Figure 1. a) The automated print technology in process based on NanoPrinter (P1), b) printing of Ir process, c) cross sectional and HR-SEM image of the thin film, d) PEMWE results Ir(VSP)-NPs tested at ambient temperature and pressure

Figure 1
Solid State Synthesis and Catalytically Active Nanoparticle Exsolution As a Novel Approach for HER Electrode Fabrication
Authors: Reinke Jakob Michael , Li Ruihan , Yi Zhiying , Seitz Linsey C , Barnett Scott A 
Published: December 2024

Increased demand for green hydrogen as part of a global effort to decarbonize will place a significant strain on global precious metal resources and drive up the price of electrolyzers. This study explores a new way of producing oxide electrode materials for proton exchange membrane electrolyzer cells (PEMECs) that may help decrease material and processing costs while potentially improving catalyst lifetime. The method is the so-called “exsolution” technique, previously used in high temperature catalysts and fuel cell electrodes (1). In exsolution, a high-temperature reduction process causes one or more cations in an oxide to be reduced to form surface metal nanoparticles. For example, Sr0.95Ti0.3Fe0.63Ru0.07O3-δ (STFR) has been shown to be an effective solid oxide cell fuel electrode where exsolution forms Ru-Fe nanoparticles that substantially enhance electrode performance (2).
Here, we compare the ambient temperature catalytic activity for the acidic hydrogen evolution reaction (HER) of pristine STFR and STFR exsolved for varying durations at temperatures ranging from 500 to 800℃ in a gas mixture of 97% H2/3% H2O. The exsolved materials demonstrate superior HER activity and stability compared to pristine STFR. As shown in Figure 1, the initial overpotential required to achieve a current density of -10mA/cm2
geo was decreased from 388 mV without exsolution to 141 mV after 4h exsolution at 700 ℃. Overpotentials generally decrease further after 1000 LSV cycles.
This paper will also show the effect of varying reduction times and gas compositions on the resulting electrocatalytic activity. Results for a different electrode composition, Sr0.95Ti0.3Fe0.63Ni0.07O3-δ (STFN), will also be presented. The electrochemical results will be related to the size and density of exsolved nanoparticles.

Figure 1: Linear Sweep Voltammetry polarization curves measured at 5 mV/s in 0.5M H2SO4 at room temperature for as-prepared STFR electrodes compared with STFR electrodes that had been reduced at various temperatures for 4 hours in 97% H2, 3% H2O prior to testing. Solid lines show the first sweep and dashed lines show the polarization after 300 voltammetry cycles for STFR without exsolution, and 1000 CVs for the exsolved STFR electrodes.

D. Neagu, J. T. S. Irvine, J. Wang, B. Yildiz, A. K. Opitz, J. Fleig, Y. Wang, J. Liu, L. Shen, F. Ciucci, B. A. Rosen, Y. Xiao, K. Xie, G. Yang, Z. Shao, Y. Zhang, J. M. Reinke, T. A. Schmauss, S. Barnett, R. Maring, V. Kyriakou, U. Mushtaq, M. N. Tsampas, Y. Kim, R. O'Hayre, A. J. Carrillo, T. Ruh, L. Lindenthal, F. Schrenk, C. Rameshan, E. I. Papaioannou, K. Kousi, I. Metcalfe, X. Xu and G. Liu, Journal of Physics: Energy (2023).

R. Glaser, T. Zhu, H. Troiani, A. Caneiro, L. Mogni and S. Barnett, Journal of Materials Chemistry A, 6, 5193 (2018).

Figure 1
The Effect of Polymer Chemistry of Block or Random Co-Polymers for Anion Exchange Membrane Electrolyzer Membranes and Ionomers in Carbonate Electrolyte
Authors: Herring Andrew M. , Sweeney Alana Blaise , Kuo Mei-Chen , Salgado Marco , Carroll Liam 
Published: December 2024

Of all the emerging electrolyzer technologies that can produce low carbon hydrogen, AEM electrolysis coupled with wind, solar or other renewable electricity has the greatest potential as it combines the contactless and rapid response advantages of PEM electrolysis without the need for rare or precious metal catalysts, or per fluorinated hydrocarbons, as demonstrated in the less scalable less responsive, lower power density liquid alkaline electrolysis. Indeed, AEM electrolyzer technology has the potential to meet the DOEs hydrogen earth shot goal of $1/kg H2. Practical AEM electrolysis with pure water has so far proved elusive. It has been easily shown that adding a small amount of supporting electrolyte, 0.5 - 1 M hydroxide or carbonate, to the circulating aqueous feed facilitates practical current densities. While adding 0.5 M hydroxide gives the highest performance, the use of hydroxide necessitates the use of higher cost, more caustic stable components, and the isolation of the hydroxide from air. Using 0.5 M potassium or sodium carbonate electrolytes only increases the over potential by 100 mV versus hydroxide allowing excellent performance to be achieved and saves significant system costs while excellent durability is simultaneously obtained. We utilize a scalable and versatile triblock co-polymer, ABA, polychloromethylstyrene-b-polyethylene-b-polychloromethylstyene, pCMS-pE-pCMS, polymer system that can be quaternized to give high performance and highly durable AEMs or tunable ionomers. Typically OH- conductivities are > 0.1 S cm-1 > 40°C and > 0.1 S cm-1 for all other common anions, Cl-, carbonate, bicarbonate > 70°C. In the laboratory this could easily be fabricated at high MW with complete control of A:B ratios on the 10 g scale and in the hands of a third-party it has been scaled up to >1 kg. The polymer can be processed on a tape caster to give sheets > 500 cm2 with controllable thicknesses from 10-100 ± 1μm.
Further improvements to the polymer chemistry are being investigated that will affect its performance and durability and allow us to cast higher quality thinner films. Furthermore, we are beginning to optimize the ionomer chemistry to allow ultra low loadings of Pt on the Hydrogen side and non-precious metal catalysts, such as MnO2 and Co3O4, on the Oxygen side. To achieve this we can swap the structural polyethylene for the more rubbery polymethylbutylene in our block polymers as well as make random polymers that act as excellent electrode binders. Finally we have begin to probe the effects of changing the aromatic hydrophilic group for a completely hydrocarbon polymer brush. We will present the results of testing these materials for performance and durability in an ambient pressure 5 cm2 electrolyzer at 60°C.
Advancements in the Fabrication of Reinforced Proton Exchange Membranes and Exploration of Next-Generation Membrane Technologies
Authors: Chiba Yusuke , Hayabe Shintaro , Salem William , Sawada Toshiaki 
Published: December 2024

Developing a polymer-electrolyte membrane (PEM) as a water electrolysis (WE) component is crucial for achieving a hydrogen-based economy while reducing CO2 production. Among proton exchange membranes, per-fluorinated sulfonic acid (PFSA) membranes are considered key components due to their high proton conductivity and chemical and thermal stability. Over the next few years, the demand for PFSA membranes in the PEM electrolysis market is expected to rapidly grow, necessitating suppliers to enhance their manufacturing capabilities and membrane quality.
Since 1975, AGC has been manufacturing PFSA membranes, contributing significantly to the electrolysis industry, including PEM water electrolysis and chlor-alkali electrolysis, among others. AGC R&D has developed FORBLUETM S-SERIES, a PFSA membrane for PEMWE, using PFSA polymers manufactured in-house from monomers. PFSA membranes possess the following properties: high proton conductivity, high mechanical strength and chemical stability, low gas permeability, and good dimensional stability. PFSA membrane properties can be optimized by adjusting the membrane thickness and the polymer’s ion exchange capacity (IEC). PFSA membrane dimensional stability can be enhanced using reinforcement, which reduces changes in the in-plane dimensions upon the water uptake and facilitates efficient MEA construction. We have developed two reinforced membranes, Sx-0935DH and Sx-1235DH. Sx-0935DH shows high proton conductivity, and Sx-1235DH exhibits low gas permeation ability. For instance, the overpotential of Sx-0935DH was reduced by >80 mV at 3 A/cm2 compared to N115, measured under ambient pressure at 80 °C. Additionally, the hydrogen concentration on the anode side of Sx-1235DH is 20% of that of N115. Currently, we are working on manufacturing the two reinforced PFSA membranes on a large scale via roll-to-roll (RtR) processing.
In the water electrolysis industry, there is a demand for thinner membranes to increase proton conductivity and reduce the energy required for hydrogen production. However, thinner membranes tend to have a higher hydrogen permeation ability. Since the lower explosive limit (LEL) for hydrogen in oxygen is only 4 vol%, reducing the hydrogen gas crossover is critical. A gas recombination catalyst (GRC) is used as a membrane component to lower the concentration of hydrogen in oxygen. AGC is developing thinner membranes, incorporating GRC as the next-generation solution.
We will present our recent efforts in manufacturing membranes through RtR processing and developing next-generation membranes for water electrolysis.