bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Low Iridium Loading in Proton-Exchange Membrane Water Electrolysis: Scalable Synthesis of IrOx@TiO2 Core-Shell Particles
Authors: Hoffmeister Darius , Finger Selina , Fiedler Lena , Körner Andreas , Zlatar Matej , Thiele Simon , Hutzler Andreas , Pham Chuyen 
Published: February 2024

Proton-exchange membrane water electrolysis (PEMWE) is a promising technology for producing hydrogen from renewable energy sources. However, the high demand for noble metals hinders the widespread adoption of this technology. Especially the anodic catalyst layer is usually manufactured with high loadings of the scarce element iridium, typically ~2 mgIr·cm-2. As an active and stable noble-metal-free alternative to iridium catalysts has yet to be developed, the most viable strategy for the near future development of PEMWE is to reduce iridium loadings as much as possible. Lowering the iridium loading to values below 0.5 mgIr·cm-2, however, often leads to inhomogeneous catalyst layers resulting in disconnected catalyst islands.1, 2 In two related contributions, we report a novel anodic catalyst for PEMWE that can overcome this limitation by forming homogeneous layers even at lower loadings, thus exhibiting high full cell performance. In this first contribution, we synthesized catalysts with less than 50 wt% iridium content to obtain low iridium loadings while maintaining electrical conductivity. The catalyst is based on the IrO2@TiO2 core-shell microparticles introduced in our previous work,3 which we optimized towards their structural and electrochemical properties. The structural properties of these novel catalysts are analyzed by scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Furthermore, the catalytic activity is evaluated by rotating disk electrode (RDE) measurements, and the electrochemical stability is assessed in a scanning flow cell setup combined with an inductively coupled plasma mass spectrometer (SFC-ICP-MS). Our catalysts outperform state-of-the-art materials in terms of mass activity in RDE measurements, while a comparable dissolution stability is achieved, as evidenced by SFC-ICP-MS measurements. In our second contribution, we show a high performance of this novel catalyst in catalyst-coated membrane (CCM) configuration with iridium loadings below the above mentioned threshold of 0.5 mgIr·cm-2. This proves that our novel IrOx@TiO2 particles with low iridium contents enable a significant reduction of iridium for the anode in PEMWE.
References:

M. Bernt, A. Siebel and H. A. Gasteiger, J. Electrochem. Soc.,
165(5), F305-F314 (2018).

C. Rozain, E. Mayousse, N. Guillet and P. Millet, Applied Catalysis B: Environmental,
182, 123–131 (2016).

C. van Pham, M. Bühler, J. Knöppel, M. Bierling, D. Seeberger, D. Escalera-López, K. J. Mayrhofer, S. Cherevko and S. Thiele, Applied Catalysis B: Environmental,
269, 118762 (2020).

Figure 1
Impact of Position and Platinum Loading of Recombination Interlayers in Proton Exchange Membranes on the Anodic Hydrogen Content in Water Electrolysis
Authors: Abbas Dunia , Martin Agate , Trinke Patrick , Bierling Markus , Bensmann Boris , Thiele Simon , Hanke-Rauschenbach Richard , Boehm Thomas 
Published: February 2024

Hydrogen crossover through the membrane is a significant safety concern in proton exchange membrane water electrolyzers (PEMWEs). This issue is predominant at low loads, which contradicts the application of PEMWEs in conjunction with fluctuating renewable energy sources that require the electrolyzer to switch between low- and high-load operation. The risk of flammable or explosive oxygen-hydrogen mixtures on the anode side of the electrolyzer prevents the application of membranes as thin as in fuel cells, which results in relatively large Ohmic losses. A means to mitigate the accumulation of hydrogen in the oxygen compartment is the integration of platinum nanoparticles as a recombination catalyst interlayer within the membrane that catalyzes the recombination of hydrogen and oxygen to water. It was shown that such an interlayer effectively minimizes the hydrogen concentration on the anode side without reducing the cell performance.1 Thus, this technology can pave the way toward thinner membranes and more efficient electrolyzers.
However, the interlayer should not increase the costs of the membrane electrode assembly by excessive Pt loading. Hence, we investigated the ideal position of this recombination interlayer within the membrane,2 and we performed a parameter study on the minimum required catalyst loading for an effective hydrogen-in-oxygen reduction.3 We find that the best position for the interlayer is close to the anode due to the lower oxygen permeability of the membrane. Also, a loading of 10 µg per cm² of platinum nanoparticles is sufficient to reduce the anodic hydrogen content from more than 2.5 vol.% (without interlayer) to approx. 0.5 vol.% when operating a PEMWE cell with a 110 µm thick membrane at 0.5 A/cm² and a differential pressure of 10 barc/1 bara. In summary, we are able to show that low platinum loadings within the membrane are sufficient to reduce the anodic hydrogen content in PEMWEs to safe values without impairing the electrochemical performance of the cell.
References

C. Klose, P. Trinke, T. Böhm, B. Bensmann, S. Vierrath, R. Hanke-Rauschenbach and S. Thiele, J. Electrochem. Soc.,
165(16), F1271-F1277 (2018).

A. Martin, D. Abbas, P. Trinke, T. Böhm, M. Bierling, B. Bensmann, S. Thiele and R. Hanke-Rauschenbach, J. Electrochem. Soc.,
168(9), 94509 (2021).

D. Abbas, A. Martin, P. Trinke, M. Bierling, B. Bensmann, S. Thiele, R. Hanke-Rauschenbach and T. Böhm, J. Electrochem.
Soc.,
169(12), 124514 (2022).
(Invited) Electron Microscopy Investigation of Electrolyzer Degradation
Authors: Cullen David A. , Yu Haoran , Arregui-Mena David , Padgett Elliot , Alia Shaun M , Bender Guido , Komini Babu Siddharth , Mukundan Rangachary 
Published: February 2024

Low-temperature proton exchange membrane water electrolyzers (PEMWEs) are a key technology for green hydrogen production from renewable energy sources. Developing efficient and durable components for the membrane electrode assembly (MEA) at the heart of the electrolyzer is critical for meeting DOE’s Hydrogen Shot target of $1 per kg of hydrogen by 2031. Of key interest to the efficiency and longevity of the electrolyzer is the anode-side of the MEA, where the costly iridium (Ir) catalyst is prone to dissolution at the high potentials and acidic conditions experienced in the cell. Further, the interfacial contact resistance between the catalyst and porous transport layer (PTL) plays a key role in electrolyzer performance and can degrade over time. Understanding and mitigating these degradation modes is critical for reducing the cost the PEMWEs and enabling commercialization.
Here we will present the results of electron microscopy characterization performed on degraded anode catalyst layers and coated PTLs. Cross sections of MEAs submitted to different cycling protocols (square wave, triangle wave, steady-state, etc.) were prepared by diamond-knife ultramicrotomy and studied with in the scanning transmission electron microscope (STEM). Using energy dispersive X-ray spectroscopy (EDS), the dissolution and migration of Ir into the membrane was tracked and correlated with performance losses. The impact of PTL contact area on inhomogeneous degradation in anodes with low catalyst loadings will also be presented. In addition, PTL coating thickness and uniformity will be correlated with interfacial contact resistance measurements using a combination of focused ion beam (FIB), scanning electron microscopy (SEM) and STEM-EDS.
Funding for this work was provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the H2NEW Consortium. Electron microscopy research conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
Efficient Alkaline Hydrogen Evolution Reaction Using Superaerophobic Ni Nanoarrays with Accelerated H2 Bubble Release
Authors: Kim Jaerim , Jung Sang-Mun , Kim Yong-Tae , Kim Jong Kyu 
Published: February 2024

Water electrolysis for producing green hydrogen is of central importance in the hydrogen economy to meet the global mission of carbon neutrality. Hydrogen evolution reaction (HER) under alkaline conditions has many advantages in cost and stability over acidic HER, but it requires high overpotential due to sluggish reaction kinetics. Pt-based materials are still considered the benchmark for HER catalysts, however, their high cost is the major hurdle for large-scale applications, motivating tremendous efforts to find earth-abundant catalytic materials as alternatives.
In addition to catalytic materials, the formation and release of H2 bubbles on the surface of catalysts should be considered when designing efficient catalysts, as this significantly affects catalytic performance. Adhered H2 bubbles on the catalyst surface can cause reduced active surface sites, blockage of ion pathways, and destruction of catalyst film by inducing a large stretch force. Despite the adverse effects of H2 bubbles adhering to catalyst’s surface on the performance of water electrolysis, the mechanisms by which H2 bubbles are effectively released during the alkaline HER remain elusive.
In this study, we conducted a systematic investigation on the effect of nanoscale surface morphologies on H2 bubble release behaviors and HER performance by employing earth-abundant Ni catalysts consisting of an array of Ni nanorods (NRs) with controlled surface porosities. Both aerophobicity and hydrophilicity of the catalyst’s surface vary according to the surface porosity of catalysts. The Ni catalyst with the highest porosity of ~52% exhibits superaerophobic nature as well as the best HER performance among the Ni catalysts. It was found that the Ni catalyst’s superaerophobicity combined with the effective open pore channels enables the accelerated release of H2 bubbles from the surface, leading to a significant improvement in geometric activities, particularly at high current densities, as well as intrinsic activities including both specific and mass activities. It was also demonstrated that the superaerophobicity enabled by highly porous Ni NRs can be combined with Pt and Cr having optimal binding abilities to further optimize electrocatalytic performance. Our work can help to elucidate the fundamental and practical design rules for efficient alkaline HER catalysts consisting of earth-abundant elements.
(Digital Presentation) Metal Alloy Nanoparticles Dispersed in Amorphous Titanosilicate for Hydrogen Evolution Reaction Catalyst with Much Lower Overpotential Than That of Benchmark Catalyst in a Wide pH Range
Authors: Vemula Koteswararao 
Published: February 2024

Different kinds of metallic nanoparticles (Pd, Pt, Au, Cu, Ag etc.) are widely used in Electrochemical, Optoelectronic and Photovoltaic applications to harvest sunlight in order to increase the efficiency of devices.
ETS-10, which is a synthetic microporous material consisting of –Ti-O-Ti-O-Ti- quantum wires running along [110] and [1-10] direction in polymorph B, has been of great interest in many applications like Electrochemical, Optoelectronic and Photovoltaic applications, due to its so unique (it contains periodically positioned quantum wires [-O-Ti(O-)4-O-] with a diameter (d) of ∼0.67 nm running along the two perpendicular directions in the crystal, tetrahedral framework structures and compostion, well defiend acidity, uniform pores, highly cation exchange selectivity, and good thermal stability are widely used as commercial catalysts, ion exchangers, and adsorbants) properties.
As a results, Tafel slop clearly indicated that performance was much better than pure Pt plate and the quite stable upto 72 hours at all pH conditions.

Figure 1
(Invited) High Performing Fuel Cell Stack and Systems
Authors: Bodén Andreas , Kylhammar Lisa , Dombrovskis Johanna , Göransson Gert 
Published: February 2024

PowerCellGroup has worked in the field of fuel cell systems and fuel cell stacks for more than 25 years. The development of both systems and stacks have gone hand in hand and have been important to reach the targets for both.
The fuel cell stack currently offered to the market has been developed during the last 10 years. Starting out with focus on passenger vehicles to achieve the requirements on power density. The second step the development was tailored to meet the demands from heavy-duty usage, that requires high efficiency at high power output and longer durability as well as increased operating temperature. This second stage unlocked the usage of fuel cell in more applications like, stationary high-power generation, off-rad machinery and lately the aviation sector.
The later years the implementation of hydrogen and fuel cell on the market have accelerated and more commercial usage putting larger requirement on higher power, longer durability, higher operating temperatures etc. For example, how to install several MW into marine vessels.
The third phase that we are now entering is to take the fuel cell to the next level, to the sky. Improving power density towards 5-6 kW/kg, operating temperature up to 120°C, and larger stack sizes 300 kW scalable to about 1 MW this to meet the higher power demand by aircraft. PowerCell is on a good track in all these aspects to be ready for the future. In this talk will be about how we constantly improving and challenging the fuel cell system and fuel cell stacks to be used in commercial operation.
Kinetics of Charge Transfer at Carbon-Based Counter Electrodes for Dye-Sensitized Solar Cells with Aqueous Electrolytes
Authors: Holzhacker Daniel , Ringleb Andreas , Schlettwein Derck 
Published: February 2024

Dye-sensitized solar cells (DSSCs) might provide a highly sustainable alternative for next generation photovoltaics. This is due to their low-energy production from abundant materials, short energy payback time, high efficiency under low illumination intensities (i.e., diffuse light or indoor conditions), and versatile concepts of applications. However, some commonly used electrolyte components are environmentally problematic. Acetonitrile or other volatile organic solvents, e.g., as well as carcinogenic cobalt complexes should not leak from DSSCs. Sealing foils, however, which are typically used to prevent such leakage, carry a risk of long-term failure.
Replacing the organic solvent by water offers several advantages, as it is environmentally benign, less volatile and the cell function, further, cannot be damaged by the intrusion of water vapor. Instead of Co-complexes, e.g., the stable organic radical TEMPO (2,2,6,6-tretramethylpiperidine-1-oxyl) can serve as an alternative redox mediator with a highly positive redox potential (0.71 V vs. NHE). Using TEMPO, power conversion efficiencies (PCE) of up to 4.3% and high open-circuit voltages (V
oc = 0.955 V) have been reported.[1] However, the use of TEMPO is limited by its solubility in water (C
max < 0.15 M). Its derivative 4-hydroxy-TEMPO (OH-TEMPO) possesses a significantly higher solubility in water (C
max > 2 M) and a more positive redox potential (0.81 V vs. NHE), making it a promising candidate as a redox mediator.
In this work, we built DSSCs with TEMPO and OH-TEMPO based aqueous electrolytes, Y123-sensitized TiO2 photoanodes, and counter electrodes coated with poly(3,4-ethylenedioxythiphene) (PEDOT). For OH-TEMPO, the short-circuit current density (j
sc) and open-circuit voltage were higher than with TEMPO, but the fill factor (FF) and the PCE were significantly lower. By impedance studies, large charge transfer resistances at the counter electrode (R
CE) were obtained for OH-TEMPO in combination with additives such as 1-methylbenzimidazole (MBI), indicating a strong kinetic limitation of the OH-TEMPO+ reduction. However, we found that such additives as MBI or other organic compounds, are necessary to suppress recombination at the photoanode/electrolyte interface. Thus, we subsequently studied different counter electrode materials, such as platinum (reference), conducting polymers, and carbon materials, in contact to OH-TEMPO electrolytes with MBI to determine R
CE and find suitable materials for the application in DSSCs.
[1] Yang, W., Söderberg, M., Eriksson, A. I. K. & Boschloo, G. Efficient aqueous dye-sensitized solar cell electrolytes based on a TEMPO/TEMPO+ redox couple. RSC Advances 5, 26706–26709 (2015).
Heterostructure Design of Anode Materials for High-Performance Sodium-Ion Batteries
Authors: Lim Hyojun , Kim Sang-Ok 
Published: February 2024

The growing global demand for carbon neutrality has led to an increase in the use of electric vehicles and large-scale energy storage systems, which rely heavily on lithium-ion batteries. However, there are concerns about the limited availability of lithium resources, which may result in depletion and price increases in the near future. To solve this issue, researchers are actively exploring alternative next-generation secondary battery systems to replace current lithium-ion batteries. Sodium-ion batteries have received significant attention as one of promising candidates, as sodium is abundant in the earth's crust and economically viable compared to lithium.
Although hard carbon has been considered a reversible anode material capable of sodium-ion insertion and extraction, high-capacity anode materials are required to increase the energy density of sodium-ion batteries. Among various candidates, conversion- and alloy-based materials are highly regarded due to their high theoretical capacity. However, challenges such as huge volume changes of active materials, sluggish reaction rates, and interfacial instability that occur during charging and discharging need to be overcome for these materials to be applied in high-performance sodium-ion batteries.
To address these challenges, herein, we designed heterostructured anodes with a unique structure by combining conversion- or alloy-based materials with a porous silicon oxycarbide (SiOC) nanocoating layer, which possesses high surface capacitive reactivity and mechanical strength. We controlled the dispersion of the precursors in silicon oil and performed heat treatment to synthesize high-capacity heterostructured composites (MoS2@SiOC and Sn@SiOC). Subsequently, we conducted extensive physicochemical and electrochemical characterization as well as post-mortem analysis to investigate the properties of these composites, with a specific focus on the impact of the heterostructure on their battery performance. We anticipate that this heterostructure approach will pave the way for the development of novel, high-performance anode materials for sodium-ion batteries in the future.
Rationally Designed in-Situ Gelled Polymer-Ceramic Hybrid Electrolyte Enables Superior Performance and Stability in Quasi-Solid-State Lithium-Sulfur Batteries
Authors: Shah Vaidik , Joo Yong Lak 
Published: February 2024

Despite boasting giant leaps in performance improvement over the years, the current commercial standard, Li-ion batteries, are fast approaching their theoretical limits. Meanwhile, Lithium-Sulfur (Li-S) batteries offering ultra-high theoretical energy density (～2600 Whkg-1), cost-effectiveness, and nontoxicity are being seen as promising alternatives. Despite their plentiful advantages, the practicality of Li-S batteries has been largely stymied by several challenges: a) deleterious polysulfide dissolution and ‘shuttle effect’, b) significant volume change of S cathodes during cycling, c) safety concerns with flammable traditional glyme-based electrolyte, and d) the instability of Li anode. To mitigate these challenges, researchers have explored all-solid-state electrolytes, but their poor Li-ion conductivity, high interfacial impedance, and need for expensive, exotic materials and complex fabrication procedures severely limit their practical application.
To overcome these challenges, we propose an in-situ gelled polymer-ceramic hybrid silsesquioxane-based electrolyte system. The gelled matrix, thermally crosslinked post cell fabrication, immobilizes the glyme-based liquid electrolyte and exhibits high liquid-like ionic conductivities (1.03 mS.cm-1), low interfacial impedance, and high oxidative potential (>4.5V vs. Li/Li+) . In this study, in addition to vastly decreased flammability, we report superior Li-ion conductivity compared to state-of-art solid-state Li-S electrolytes. This high ionic conductivity translated to a significantly improved specific capacity of 1050 mAh.gS-1 at 0.2 C, elevated Coulombic efficiencies (>98.5%), and elevated rate kinetics. The gelled electrolytes exhibited stable cycling in a large temperature range (-10oC - 60 oC). Moreover, polysulfide permeation studies and subsequent DFT calculations revealed that the gelled electrolyte exhibited strong chemical absorptivity to lithium polysulfides due to the polar silsesquioxane core, which translated to superior capacity retention (>80% over 200 cycles). Further, post- mortem XPS characterization studies revealed the formation of stable SEI at the anode and cathode, and SEM of cycled anodes showed reduced dendritic formations. Finally, the electrolyte was tested in practical pouch cell architecture, and the cells demonstrated excellent reliability even under mechanical stress. This work successfully reports a robust, rationally designed gelled electrolyte system for developing safe and high-performance quasi-solid state Li-S batteries.
Chimie Douce Derived K-Based P2-Type Transition Metal(s) Layered Oxides for Secondary K-Ion Batteries
Authors: Jha PawanKumar Kumar , Barman Pubali , Abakumov Artem M. , Fichtner Maximilian , Barpanda Prabeer 
Published: February 2024

Owing to great societal and technological benefits, there has been a remarkable growth in the industrial demand for enhanced energy storage for many target applications including electric vehicles, aerospace applications, and portable electronics. Secondary K-ion batteries (KIBs) are among the potentially inexpensive candidates for energy storage systems beyond state-of-the-art Li-ion batteries (LIBs). Electrochemical cells based on mobile carrier K+ can provide efficient energy storage because of comparative ionic diffusion in bulk and swift charge transfer at the interface due to weak Lewis’s acidity.1,2 Despite various advantages over LIBs and NIBs, the roadblock of practical KIB implementation lies in identifying suitable cathodes that reversibly (de)intercalate K+ at optimum voltage, swift rate, and with prolonged cycle life.
Despite constant efforts to develop new cathodes for K+ -ion batteries, several challenges such as low concentrations of K-ions due to strong electrostatic repulsions between the K+ - K+ ions and difficulty in preparation from direct synthesis routes3 limit its practical application. In this scenario, we have adopted the chimie douce (soft chemistry) method to design the novel layered transition metal oxide cathode from the parent P2 type Na-based system. In addition, we have probed the ion exchange mechanism using X-ray diffraction and transmission electron microscopy (TEM) techniques. Rietveld analysis confirmed the structure having a P2-type stacking sequence with hexagonal symmetry and P6/3mmc space group. Further, we have successfully examined the chemical ion-exchanged novel layered P2- K2/3Co1/3Mn2/3O2 as a cathode for KIB at ambient and high temperatures. It delivered a good capacity (~70 mAh/g) with an average redox potential of 3.0 V along with good cycling stability and coulombic efficiency (CE) in temperature ranging from 25-50 ºC. Ex-situ X-ray diffraction analysis and potentio/galvanostatic titration techniques were used to analyse the K+ insertion mechanism. This study can assist in developing new insertion K+ host materials for viable and reliable practical applications.
References:

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