bluuebunny/crossref_metadata_2025_split huggingface dataset:
Producing Hydrogen with Less Energy in Ammonia Electrolyzer Stack Using Pt-Ir Catalyst Dual-Layer Electrode
Authors: Yoon Donghyun , Lee Jaeyoung 
Published: August 2024

Electrochemical ammonia decomposition has recently been regarded as a possible future technology for CO2-free hydrogen production. Pt-based catalysts have already known for having excellent activity in ammonia oxidation reactions (AOR) due to the fast dehydrogenation step enabled by the moderate adsorption strengths of nitrogen species [1]. Among them, the incorporation of Ir into Pt notably decreases the activation energy required for ammonia oxidation on Pt, lowing onset potential in alkaline media [2]. Besides, the electrolysis of ammonia has a less energy consumption than water electrolysis because of the lower operating voltage at the Anode [3]. In this study, we fabricated dual-layer electrode containing Pt-Ir catalyst, enhancing the AOR catalytic activity and showing long-term stability. The ammonia electrolysis single-cell with an anion exchange membrane (AEM) was successfully operating and then scaled up to a large area stack cell. We observed that this electrolyzer stack cell produced high-purity hydrogen using less energy than water electrolysis.
Acknowledgements
This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (NRF-2021K1A4A8A01079455). This work was also supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) [No. 2021R1A5A1028138].
Reference
[1] J. Liu, Z. Liu, Adv. Funct. Mater 2022, 32, 2110702
[2] A. Estejab, G. G. Botte, Comput. Theor. Chem 2016, 1091, 31-40
[3] J. Gwak, M. Choun, ChemSusChem 2016, 9, 403–408
PFAS-Free: Robust and Chemically Stable Ion-Solvating Polymer Membrane Derived from Poly(arylene alkylene) for High-Performance Alkaline Water Electrolysis
Authors: Rajappan Sinu Charamchirail , Xia Yifan , Serhiichuk Dmytro , Kraglund Mikkel Rykær , Aili David , Jensen Jens Oluf Oluf 
Published: August 2024

Polymeric ion-solvating membranes1 derived from poly(arylene alkylene)s2 have emerged as promising candidates for alkaline water electrolysis, offering a PFAS-free, robust, and chemically stable alternative. This work focuses on the development of such a membrane with an emphasis on high resistance to gas crossover, addressing the challenges associated with conventional ion-exchange materials.
The polymer membrane presented in this study demonstrated very good performance in alkaline water electrolysis. At 80 degrees Celsius, the membrane exhibits a specific conductivity of 36 mS/cm, underscoring its ion-solvating ability and efficiency in a 20 wt% KOH solution. The electrochemical performance is exemplified by the attainment of a 700-mA current below 2.6V with uncatalyzed nickel foam electrodes, showcasing the superior conductivity and efficiency in facilitating the electrolysis process.
One of the key features of these membranes is their longevity, as evidenced by their ability to operate for more than 200 hours without any discernible voltage decay. This extended operational lifespan underscores the robustness and durability of the developed membranes, making them highly suitable for practical applications in alkaline water electrolysis.
Furthermore, the membranes exhibit a high resistance to gas crossover, addressing a common challenge in electrolysis systems. This property ensures enhanced selectivity and efficiency by minimizing unwanted reactions and improving the overall electrolysis process.
In conclusion, the presented work signifies a significant advancement in the development of ion-solvating polymer membranes derived from poly(arylene alkylene) for alkaline water electrolysis. The membranes not only outperform existing alternatives but also offer a sustainable and environmentally friendly solution by being PFAS-free. The demonstrated high performance, stability, and resistance to gas crossover make these membranes promising candidates for the advancement of alkaline water electrolysis technology, contributing to the development of efficient and environmentally conscious hydrogen production systems.

Keywords: Alkaline; electrolysis; Poly (arylene alkylene)s; membranes; ion-solvating

References:

Aili, D.; Kraglund, M. R.; Rajappan, S. C.; Serhiichuk, D.; Xia, Y.; Deimede, V.; Kallitsis, J.; Bae, C.; Jannasch, P.; Henkensmeier, D.; Jensen, J. O. ACS Energy Lett.
2023, 8, 1900–1910.

Zolotukhin, M. G.; Fomine, S.; Lazo, L. M.; Hernndez, M. D. C. G.; Guzmáln-Gutiérrez, M. T.; Ruiz-Trevino, A.; Fritsch, D.; Cuellas, D. C.; Fernandez-G., J. M. High Perform. Polym. 2007, 19, 638–648.
A Literature Survey of Transition Metal Boride, Carbide, Pnictide, and Chalcogenide Water Oxidation Electrocatalysts
Authors: Kawashima Kenta , Marquez Raul A. , Smith Lettie A. , Vaidyula Rinish Reddy , Carrasco Jaim Omar Ali , Wang Ziqing , Son Yoon Jun , Cao Chi L. , Mullins Charles Buddie 
Published: August 2024

Transition metal borides, carbides, pnictides, and chalcogenides (X-ides) are a new class of oxygen evolution reaction (OER) electrocatalysts, which have become a relevant topic for electrocatalytic energy conversion and storage research. This is because of their earth abundance, high electrical conductivity, and resultant high OER performance. Furthermore, some X-ide electrocatalysts demonstrate various degrees of oxidation resistance under OER potentials due to their differences in chemical composition, crystal structure, and morphology. Interestingly, there are three possible post-OER electrocatalyst models: a fully oxidized oxide/(oxy)hydroxide material, a partially oxidized core@shell structure, and an unoxidized material.1 In the past ten years (from 2013 to 2022), over 890 peer-reviewed research papers have focused on X-ide OER electrocatalysts. Recently, several topical reviews have been published. However, typically these literature reviews have provided limited conclusions targeted at only certain X-ides. Additionally, certain reviews omit key points, especially regarding the “catalytically active species” in X-ide OER electrocatalysts.
In this work, we provide a comprehensive summary of (i) the experimental parameters (e.g., substrates, electrocatalyst loading amounts, electrocatalyst shapes, geometric overpotentials, Tafel slopes, etc.) and (ii) the details of the electrochemical stability tests and following post analyses used in all the X-ide OER electrocatalyst publications from 2013 (the birth of this research area) to 2022.2 In particular, based on the reported post-OER analytical results, we attempt to exhaustively classify all the X-ide electrocatalysts into four groups: no oxidation, partial oxidation, full oxidation, and unknown, which is relevant to the nature of the “catalytically active species” in X-ide OER electrocatalysts. After investigating the simpler X-ide systems, transition metal-based polyanion compounds/composites are also surveyed. Finally, we introduce the reported novel and special analytical techniques employed for observing X-ide reconstruction (i.e., oxidation and other phase transformations) during OER testing, which can be useful in selecting the analytical technique of maximum utility for the researchers’ purpose. Additionally, for each material sub-group (e.g., borides, carbides, nitrides, phosphides, sulfides, selenides, and tellurides), we also point out further challenges to be addressed and propose further questions yet to be answered, which may provide clues pointing to future research tasks.

References

B. R. Wygant, K. Kawashima, and C. B. Mullins, ACS Energy Lett., 3, 2956–2966 (2018).

K. Kawashima et al., Chem. Rev., 123, 12795–13208 (2023).
(Invited) IrOx Nanoparticle Catalysts on a Unique Microstructure of Doped Tin Oxide to Dramatically Boost the Oxygen Evolution Reaction Activity for PEM Water Electrolysis
Authors: Kakinuma Katsuyoshi 
Published: August 2024

Proton exchange membrane water electrolyzers (PEM WEs) has a potential to produce high-purity green hydrogen. PEMWEs have been commercialized with the use of high loadings of the noble metal Ir-based anode catalyst for the oxygen evolution reaction (OER). To lower the Ir loading amount, it is critically important to develop efficient catalysts with increased Ir utilization and higher OER activity. One-dimensional Ir oxide nanorod/nanoparticles catalysts supported on doped SnO2 with a unique microstructure were invented to show their exceptionally high activity in the OER catalysis, with the Ir-mass specific activity being 10 times higher than that of commercial IrOx catalyst at 1.5 V vs. RHE.[1] The experiment also found that the OER activation energy was greatly lower than that of commercial Ir oxide. The interaction between Ir oxide nanorod/nanoparticles and doped SnO2 support occurs a lower degree of Ir oxidation which allows the surface terminal oxygens to be closer together while allowing facile desorption of nonreactive oxygenated species. The electronic state of Ir oxide nanorod/nanoparticles catalysts could play an important role in facilitating the crucial step of the OER, thereby enhancing the OER activity. These priorities of the catalysts would promise the reduction of the Ir usage in PEMWEs.
Reference
[1] G. Shi, T. Tano, D.A. Tryk, T. Uchiyama, A. Iiyama, M. Uchida, K. Terao, M. Yamaguchi, K. Tamoto, Y. Uchimoto and K. Kakinuma, ACS Catalysis, 13 (2023) 12299.

Figure 1
Water Management in Anion Exchange Membrane Fuel Cells Via Distribution of Relaxation Times Analysis
Authors: Haodong Huang , Zeng Lin , Zhao Tianshou 
Published: August 2024

In response to growing concerns regarding air pollution and energy scarcity, anion exchange membrane fuel cells (AEMFCs) have emerged as a promising technology for power generation due to their high efficiency, zero emissions, and the abundance of hydrogen resources. Within AEMFCs, water serves as a reactant, being consumed at the cathode, and generated at the anode, which can lead to an imbalance in the water content within the fuel cell. Maintaining an appropriate water distribution is essential for efficient charge transport and electrochemical reaction kinetics. Therefore, the development of a comprehensive water management strategy is crucial to ensure the stable operation and durability of AEMFCs.
Characterizing the water condition of the anode and cathode in different operation conditions (normal, drying, or flooding) is a critical step that provides data foundation for devising effective water management control strategies. Electrochemical impedance spectroscopy (EIS) offers a means to investigate different resistances (kinetics, mass transport, and ohmic losses) over varying time scales during operation to assess water transport. The conventional interpretation of EIS data typically relies on equivalent circuit models, necessitating prior assumptions and initial component selections. In this study, we employed the distribution of relaxation times (DRT) methodology, known for its powerful ability to separate components, to conduct a more precise analysis of polarization processes. Initially, electrochemical impedance dynamics related to hydroxide transport, hydrogen oxidation reactions, and oxygen reduction reactions were effectively extracted. Subsequently, DRT was employed to investigate the loss and variation trends of each polarization process under conditions of anode and cathode water flooding and drying conditions, respectively. Furthermore, to gain a deeper understanding of the effects of water content on mass transport and electrochemical reaction kinetics, a three-dimensional multi-physics model for AEMFCs was developed. This model incorporated water phase transition, heat and mass transfer, liquid water and dissolver water transport, and electrochemical reactions. These endeavors represent a comprehensive and systematic approach to guide the utilization of the distribution of relaxation times in fuel cells.
Ag/Nico LDH Heterogeneous Structure for Efficient Alkaline Oxygen Evolution
Authors: Shao Minhua , Sun Yan 
Published: August 2024

Hydrogen is regarded as an ideal energy carrier owing to the highest energy density, presenting the possibility of substituting for traditional fossil fuels. Nowadays, water splitting is significant in producing large-scale hydrogen. However, the sluggish reaction kinetics during anodic OER, caused by the four-electron transfer, has hindered this energy conversion strategy. Although IrO2 and RuO2 are currently the representative OER electrocatalysts, their high cost and unsatisfactory performance limit their commercial application.
Numerous electrocatalysts, including oxides, hydroxides, high-entropy alloy, metal organic frameworks, and their hybrids, have been developed to address this issue. Among them, layered double hydroxides (LDH) have demonstrated outstanding performance due to their highly adjustable structure, powerful host-guest interaction, and single-atomic-like active sites. NiCo LDH has attracted significant attention because of its appropriate atomic and electronic structure, intrinsic active sites and defects, compared with single-type Ni-based or Co-based catalysts. However, to meet the requirements of industrial production, a simple and scalable method to synthesize electrocatalysts with favorable OER activity and stability is imperative.
We propose a facile and scalable strategy to synthesize Ag-decorated NiCo LDH (Ag/NiCo LDH) by electrodeposition and subsequent spontaneous redox reaction. A spontaneous redox reaction driven by the difference in standard redox potential of reactants can be applied to prepare heterogeneous catalysts in consequence of the facile process, tight combination between substrate and decorated materials, and no supplementary energy input. Silver metal, with its appropriate standard redox potential, good conductivity, and low cost compared to Iridium and Ruthenium, serves as a suitable decorated material. This strategy provides several advantages, for example, Ⅰ) optimizing the electronic structure of Ni and Co by the charge transfer from Ni, Co to Ag; Ⅱ) exposing more active surface area because of the heterogeneous structure, Ⅲ) improving the charge transfer capacity owing to the excellent conductivity of Ag nanoparticles, Ⅳ) increasing the stability of NiCo LDH due to the tight combination of Ag and NiCo LDH, Ⅴ) lowering the catalysts' price compared with Iridium and Ruthenium.
The synthesized Ag/NiCo LDH exhibits enhanced OER performance in 1M KOH electrolyte, achieving an overpotential of 440 mV at a current density of 1000 mA cm-2
geo, surpassing that of NiCo LDH (722 mV at 1000 mA cm-2
geo). Surprisingly, Ag/NiCo LDH demonstrates exceptional durability, lasting over 425 h at 1000 mA cm-2
geo, an improvement of nearly eight-fold compared to NiCo LDH (50 h). This study provides a promising approach for developing efficient and stable electrocatalysts for alkaline oxygen evolution.
Stability of Bipolar Plates in Proton Exchange Membrane Water Electrolysis: Dissolution Studies of Titanium and Stainless Steel
Authors: Fiedler Lena , Ma Tien Ching , Fritsch Birk , Risse Jan Henning , Lechner Michael , Dworschak Dominik , Merklein Marion , Hutzler Andreas , Mayrhofer Karl J. J. 
Published: August 2024

Due to its high current densities and fast system response proton exchange membrane water electrolysis (PEMWE) is an ideal system for green hydrogen production from renewable energies. However, its widespread use is still hindered by the high costs rendering the produced green hydrogen not competitive. Therefore, a cost reduction is highly needed. The bipolar plates (BPPs) are causing a colossal factor in material costs. They are usually produced from titanium and coated with even more expensive materials such as gold or platinum. A possible, cheaper alternative is stainless steel. However, it is suspected to suffer from corrosion leading to the leaching of cations that can poison the catalyst or membrane.[1] Thus, we investigated the stability of BPP materials, the currently used titanium, and its cheaper alternative stainless steel (316L).[2]

Therefore, we use a modified scanning flow cell setup coupled to an inductively coupled plasma mass spectrometer for investigating the stability of both materials on-line, as well as with scanning electron microscopy. To mimic the conditions at the BPP under operation, deionized (DI) water and highly diluted (0.5 mM) H2SO4 are chosen as electrolytes combined with a sample temperature of 60 °C.
For Ti, we show that the dissolution is negligible, whereas 316L corrodes. For 316L, in DI water mainly Cr dissolves, while in the H2SO4 solution, the dissolution is more pronounced, and all alloy components are detected. Besides the pH value, the applied potentials play a crucial for its stability. However, our findings suggest that the contamination for a typical full cell architecture remains below 1 ppm, even for the highest measured dissolution rate of SS 316L.
These capabilities of on-line high-throughput stability tests for BPP materials are, furthermore, used to investigate the influence of contaminations, such as F- or Cl-, and of the temperature-dependence on the stability of 316L. These results give further insights into 316L stability as BPP material and therefore contribute to the development towards cost-effective PEMWE.
[1] a) N. Rojas, M. Sánchez-Molina, G. Sevilla, E. Amores, E. Almandoz, J. Esparza, M. R. Cruz Vivas, C. Colominas, Int. J. Hydrogen Energy
2021, 46, 25929-25943; b) H. Becker, J. Murawski, D. V. Shinde, I. E. L. Stephens, G. Hinds, G. Smith, Sustain.
Energy Fuels
2023, 7, 1565-1603.
[2] L. Fiedler, T. C. Ma, B. Fritsch, J. H. Risse, M. Lechner, D. Dworschak, M. Merklein, K. J. J. Mayrhofer, A. Hutzler, ChemElectroChem
2023, e202300373.

Figure 1
Photocatalytic Methane Oxidation and Removal Mediated by Free Radicals
Authors: Wan Gang , Majumdar Arun 
Published: August 2024

Activation and selective oxidation of C-H bond in methane under mild conditions constitutes long-standing challenges which are of fundamental and technological importance, from biological to industrial and environmental. Earth relies on free radicals to remove the climate-damaging methane and other organic pollutants from the air. In recent decades, intensive efforts have been focused on leveraging free radicals for selective methane oxidation. Free radicals are one of key mediators underpinning many active sites in thermal catalysis and these enhancement effects induced by the light and electric fields. However, it remains unclear how free radicals as active species mediate the C-H bond activation in methane and dictate the products distribution.
In this talk, we will discuss our recent advances in understanding and promoting the photocatalytic oxidation of methane to methanol by combining the rational design of photocatalysts, photochemical experiments, as well as the in-situ electron paramagnetic resonance studies of free radicals. Our results unravel interactions between these free radicals and the solid co-catalysts, ions, and gases molecules in water, as well as their impact on methane removal and its selective oxidation. Our studies highlight the neglected while important interplay between photogenerated radicals and co-catalysts, ion impurities, and gas molecules in promoting methane removal and controlling the products distribution. Furthermore, we report an inherent trade-off in the photochemical methane to methanol conversion. A new design principle featuring isolating different reaction steps is developed to circumvent this trade-off.
Such molecular-level insights into photocatalysts and their interactions with free radicals are expected to promote the methane removal and its selective functionalization and offer informative design principles for chemical bonds activations that are driven by light, heat, and electric fields.
(Invited) Near Field Photocatalysis for Site-Selective Reactions By Using ZnO Nanoplates
Authors: Tatsuma Tetsu , Lee Seung Hyuk , Oba Yuki , Horiuchi Genki 
Published: August 2024

Nanofabrication is a technology for control of the morphology, orientation, and configuration of nanomaterials. When ordinary, propagating light is employed as a processing tool, subwavelength fabrication is difficult due to the diffraction limit. However, if optical near field, which is localized in a subwavelength region is used, nanofabrication beyond the diffraction limit is possible.
We have demonstrated that subwavelength nanofabrication is possible by taking advantage of the optical near field. Since hot electron-hole pairs are generated at around the plasmonic resonance sites, the energetic carriers can be used to drive oxidative dissolution of Ag,1,2 oxidative deposition of PbO2,3,4 and reductive deposition of Ag,5 in a site-selective manner. These techniques have been applied to subwavelength photochromic data storage,1,2 fabrication of chiral nanoparticles,4-7 and site-selective modification of a plasmonic photocatalyst with a co-catalyst.8

Generation of optical near field is possible even at non-plasmonic, semiconducting or dielectric nanostructures. Here we employed In-doped ZnO (In:ZnO) as a semiconductor photocatalyst. Hexagonal In:ZnO nanoplates were synthesized and adsorbed onto a glass substrate, and irradiated with linearly polarized UV light in the presence of Ag ions for reductive deposition of Ag. The optical near field generated under polarized UV light gave rise to site-selective Ag deposition. Also, the sample exhibited linear dichroism (LD) signals, indicating that the nanoparticles have optical anisotropy. On the other hand, unpolarized UV light gave no optical anisotropy. Electromagnetic simulations successfully reproduced the LD spectra. We have also performed site-selective oxidation reactions by using the hexagonal In:ZnO nanoplates.

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