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136 results on '"Schreuders, Herman"'

1. Hydrogenation kinetics of metal hydride catalytic layers

Author

Bannenberg, Lars and Schreuders, Herman

Subjects
Condensed Matter - Materials Science
Abstract

Catalyzing capping layers on top of metal hydrides are often employed to enhance the hydrogenation kinetics of metal-hydride based systems such as hydrogen sensors. Here, we experimentally study the hydrogenation kinetics of capping layers composed of several alloys of Pd and Au as well as Pt, Ni and Ru, all with and without an additional PTFE protection layer using a novel method and under the same set of experimental conditions. Our results demonstrate that doping Pd with Au results in significantly faster hydrogenation kinetics, with response times up to five times shorter than Pd through enhanced diffusion and a reduction of the activation energy. The kinetics of non-Pd based materials turns out to be significantly slower and mainly limited by the diffusion through the capping layer itself. Surprisingly, the additional PTFE layer was only found to improve the kinetics of Pd-based capping materials and has no significant effect on the kinetics of Pt, Ni and Ru. Taken together, the experimental results aid in rationally choosing a suitable capping material for the application of metal hydrides and other materials in a green economy. In addition, the developed method can be used to simultaneously study the hydrogenation kinetics and determine diffusion constants in thin film materials for a wide set of experimental conditions.

Published
2021

2. Tantalum-Palladium: hysteresis-free optical hydrogen sensor over 7 orders of magnitude in pressure with sub-second response

Author

Bannenberg, Lars J., Schreuders, Herman, and Dam, Bernard

Subjects
Condensed Matter - Materials Science
Abstract

Hydrogen detection in a reliable, fast, and cost-effective manner is a prerequisite for the large-scale implementation of hydrogen in a green economy. We present thin film Ta$_{1-y}$Pd$_y$ as effective optical sensing materials with extremely wide sensing ranges covering at least seven orders of magnitude in hydrogen pressure. Nanoconfinement of the Ta$_{1-y}$Pd$_y$ layer suppresses the first-order phase transitions present in bulk and ensures a sensing response free of any hysteresis. Unlike other sensing materials, Ta$_{1-y}$Pd$_y$ features the special property that the sensing range can be easily tuned by varying the Pd concentration without a reduction of the sensitivity of the sensing material. Combined with a suitable capping layer, sub-second response times can be achieved even at room temperature, faster than any other known thin-film hydrogen sensor.

Published
2020
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3. Versatile pressure and temperature controlled cell for neutron reflectometry and small-angle neutron scattering.

Author

Bannenberg, Lars J., van Exter, Martin, Verleg, Malte N., Boshuizen, Bart, Parnell, Steven R., Thijs, Michel, and Schreuders, Herman

Subjects
NEUTRON reflectometry, SMALL-angle neutron scattering, TEMPERATURE control, PRESSURE control, SMALL-angle scattering, LIGHT transmission
Abstract

We have designed and realized a temperature and pressure controlled cell for Neutron Reflectometry (NR) and Small Angle Neutron Scattering (SANS) that is compatible with simultaneous optical transmission and resistivity measurements. The cell can accommodate samples up to 102 mm (4 inch) in diameter, can be pressurized from vacuum up to 10 bar gas pressure and the sample temperature can be controlled up to 350°C. The four single crystal quartz windows ensure both a good neutron and optical transmission and hence can be used in combination with in-situ optical transmission measurements. We present the cell and illustrate its performance with a series of neutron reflectometry experiments performed on Ta based thin films under a hydrogen containing atmosphere. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Memory effect in photochromic rare-earth oxyhydride thin films studied by in situ positron annihilation spectroscopy upon photodarkening-bleaching cycling

Author

Wu, Ziying, primary, de Wit, Lidwin, additional, Beek, Melanie, additional, Colombi, Giorgio, additional, Chaykina, Diana, additional, Schreuders, Herman, additional, Schut, Henk, additional, Liedke, Maciej Oskar, additional, Butterling, Maik, additional, Wagner, Andreas, additional, Dickmann, Marcel, additional, Brück, Ekkes, additional, Dam, Bernard, additional, and Eijt, Stephan W. H., additional

Published
2024
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9. In-situ S/TEM Visualization of Metal-to-Metal Hydride Phase Transformation of Magnesium Thin Films

Author

Krishnan, Gopi, Bannenberg, Lars J., Schreuders, Herman, Jinschek, Joerg, Krishnan, Gopi, Bannenberg, Lars J., Schreuders, Herman, and Jinschek, Joerg

Abstract

In our quest for a solution to drive the decarbonization of our society and economy, hydrogen shows unique properties as a zero-emission fuel, energy storage solution, and chemical feedstock [1]. However, compact storage remains a scientific and technological challenge. Safely storing hydrogen, e.g., in the solid form of metal hydrides, has many advantages, but further improving its storage properties requires a thorough understanding of the metal-to-metal hydride phase transformation at the atomic level [1]. Although many techniques have been applied to understand these phase transformations, in-situ visualization of the transformation process is essential for a quantitative understanding [2,3]. For example, stress/strain, defects, and intermediate phase evolution during metal-to-metal hydride phase transformation are crucial to interpret the hydrogen sorption properties [4].

Published
2023

16. Nano-structural perspective for destabilization of Mg hydride using immiscible transition metal of Mn

Author

Lu, Yanshan, Asano, Kohta, Schreuders, Herman, Kim, Hyunjeong, Sakaki, Kouji, Machida, Akihiko, Watanuki, Tetsu, Dam, Bernard, Akihiko, Machida, and Tetsu, Watanuki

Abstract

合金から成る水素化物の相分離状態は、複数の水素化/脱水素化サイクルを作用させても維持される可能性がある。この効果を非混和性のMg-Mnシステムにおいて金属水素化物を不安定化するために用いた。ここで、MgxMn1-x薄膜では、MgドメインとMnドメインがナノスケールで分離している。Mnが多い組成では、MgH2からの水素脱離圧力が所定の温度で上昇し、熱力学的に不安定化したことを示した。大きな熱力学的不安定化により、MgH2は室温でも水素を可逆的に吸蔵、放出することが可能となる。MgH2の不安定化に非混和性元素を使用する方法は効果的であり、高性能度、低コストの水素貯蔵および供給システムの開発の可能性に道を拓く。

Published
2021

19. Large Polaron Conduction, Photoconductivity, and Photochromism in GdOxH3−2x Oxyhydride Thin Films.

Author

Colombi, Giorgio, Boshuizen, Bart, Chaykina, Diana, Hsu, Leyi, Schreuders, Herman, Savenije, Tom J., and Dam, Bernard

Subjects
THIN films, PHOTOCONDUCTIVITY, POLARONS, PHOTOCHROMISM, OPTICAL measurements, CHARGE carriers, TIME-resolved measurements
Abstract

At ambient conditions, rare‐earth oxyhydride thin films show reversible photochromism and photoconductivity, while their mechanism and relation are still unclear. In this work, this question is explored with in situ time‐resolved measurements of both optical and transport properties of Gd‐based oxyhydride thin films. It is found that p‐type large polaron conduction is the initial mechanism of charge transport; however, upon photo‐darkening, a 104‐fold increase of conductivity occurs, and n‐type carriers become dominant. Further, photochromism and photoconductivity are shown to originate from a single process, as indicated by the fact that the photoconductivity is exponentially proportional to the increase of optical absorption. This exponential relation, notably, cannot stem from any of the optically absorbing species thought responsible for photochromism and, therefore, suggests that their formation is accompanied by a concerted increase of negative charge carriers in the Gd oxyhydride films. [ABSTRACT FROM AUTHOR]

Published
2023
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20. Effect of Temperature and H Flux on the NH3 Synthesis via Electrochemical Hydrogen Permeation.

Author

Ripepi, Davide, Schreuders, Herman, and Mulder, Fokko M.

Subjects
TEMPERATURE effect, HABER-Bosch process, ATOMIC hydrogen, ELECTRICAL energy, ALTERNATIVE fuels, HYDROGEN, AMMONIA
Abstract

Ammonia is an indispensable commodity and a potential carbon free energy carrier. The use of H permeable electrodes to synthesize ammonia from N2, water and electricity, provides a promising alternative to the fossil fuel based Haber‐Bosch process. Here, H permeable Ni electrodes are investigated in the operating temperature range 25–120 °C, and varying the rate of electrochemical atomic hydrogen permeation. At 120 °C, a steady reaction is achieved for over 12 h with 10 times higher cumulative NH3 production and almost 40‐fold increase in faradaic efficiency compared to room temperature experiments. NH3 is formed with a cell potential of 1.4 V, corresponding to a minimum electrical energy investment of 6.6 kWh kg−1NH3 ${{_{{\rm NH}{_{3}}}}}$. The stable operation is attributed to a balanced control over the population of N, NHx and H species at the catalyst surface. These findings extend the understanding on the mechanisms involved in the nitrogen reduction reaction and may facilitate the development of an efficient green ammonia synthesis process. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Unveiling Nanoscale Compositional and Structural Heterogeneities of Highly Textured Mg0.7Ti0.3Hy Thin Films

Author

Kim, Hyunjeong, Schreuders, Herman, Sakaki, Kouji, Asano, Kohta, Nakamura, Yumiko, Maejima, Naoyuki, Machida, Akihiko, Watanuki, Tetsu, and Dam, Bernard

Abstract

薄膜は非常に有用な特性を示すことがあるが、その特性発現の理解は簡単ではない。それは構造情報が限られていることが一因である。MgリッチのMg-Tiのようなテクスチャを持つ材料に対しては特に構造情報を得ることが難しい。このような準安定の薄膜は通常の結晶構造解析では固溶体合金に見えるが、水素誘起の光透過特性は固溶体モデルでは説明ができない。本研究ではMg0.7Ti0.3薄膜の原子二体分布関数を水素化過程で測定し、Mgマトリクス中に30Å程度のTiH2クラスターが形成されることを明らかにした。これは以前に報告された化学的に分離をしているモデルを支持するものである。

Published
2020

23. Aliovalent Calcium Doping of Yttrium Oxyhydride Thin Films and Implications for Photochromism

Author

Chaykina, Diana, Usman, Ismene, Colombi, Giorgio, Schreuders, Herman, Tyburska-Pueschel, Beata, Wu, Ziying, Wijs, Gilles A. de, Dam, Bernard, Chaykina, Diana, Usman, Ismene, Colombi, Giorgio, Schreuders, Herman, Tyburska-Pueschel, Beata, Wu, Ziying, Wijs, Gilles A. de, and Dam, Bernard

Abstract

Contains fulltext : 253267.pdf (Publisher’s version ) (Open Access)

Published
2022

25. Metallurgical Synthesis of Mg2FexSi1-x Hydride: Destabilization of Mg2FeH6 Nanoconfined in Templated Mg2Si

Author

Asano, Kohta, Kim, Hyunjeong, Sakaki, Kouji, Nakamura, Yumiko, Wang, Yongming, Isobe, Shigehito, Doi, Masaaki, Fujita, Asaya, Maejima, Naoyuki, Machida, Akihiko, Watanuki, Tetsu, J. Westerwaal, Ruud, Schreuders, Herman, Dam, Bernard, Naoyuki, Maejima, Akihiko, Machida, and Tetsu, Watanuki

Abstract

Mgベースの遷移金属水素化物は安価で重量水素密度および体積水素密度が高いため、注目されている水素貯蔵材料である。しかながら、それらのほとんどは安定であり、適度な条件下で水素を放出することが困難であるという課題がある。我々は同じ立方構造のMg2FeH6とMg2Siで構成されるMg2FexSi1-xの水素化物を合成した。Siリッチの水素化物（x

Published
2020

36. Metal-polymer hybrid nanomaterials for plasmonic ultrafast hydrogen detection

Author

Nugroho, Ferry A.A., Darmadi, Iwan, Cusinato, Lucy, Susarrey-Arce, Arturo, Schreuders, Herman, Bannenberg, Lars J., Bastos da Silva Fanta, Alice, Kadkhodazadeh, Shima, Wagner, Jakob Birkedal, Antosiewicz, Tomasz J., Hellman, Anders, Zhdanov, Vladimir P., Dam, Bernard, Langhammer, Christoph, Nugroho, Ferry A.A., Darmadi, Iwan, Cusinato, Lucy, Susarrey-Arce, Arturo, Schreuders, Herman, Bannenberg, Lars J., Bastos da Silva Fanta, Alice, Kadkhodazadeh, Shima, Wagner, Jakob Birkedal, Antosiewicz, Tomasz J., Hellman, Anders, Zhdanov, Vladimir P., Dam, Bernard, and Langhammer, Christoph

Abstract

Hydrogen-air mixtures are highly flammable. Hydrogen sensors are therefore of paramount importance for timely leak detection during handling. However, existing solutions do not meet the stringent performance targets set by stakeholders, while deactivation due to poisoning, for example by carbon monoxide, is a widely unsolved problem. Here we present a plasmonic metal-polymer hybrid nanomaterial concept, where the polymer coating reduces the apparent activation energy for hydrogen transport into and out of the plasmonic nanoparticles, while deactivation resistance is provided via a tailored tandem polymer membrane. In concert with an optimized volume-to-surface ratio of the signal transducer uniquely offered by nanoparticles, this enables subsecond sensor response times. Simultaneously, hydrogen sorption hysteresis is suppressed, sensor limit of detection is enhanced, and sensor operation in demanding chemical environments is enabled, without signs of long-term deactivation. In a wider perspective, our work suggests strategies for next-generation optical gas sensors with functionalities optimized by hybrid material engineering.

Published
2019

40. Elastic versus Alloying Effects in Mg-Based Hydride Films

Author

Baldi, Andrea, Mooij, Lennard, Palmisano, Valerio, Schreuders, Herman, Krishnan, Gopi, Kooi, Bart J., Dam, Bernard, Griessen, Ronald, Baldi, Andrea, Mooij, Lennard, Palmisano, Valerio, Schreuders, Herman, Krishnan, Gopi, Kooi, Bart J., Dam, Bernard, and Griessen, Ronald

Abstract

Magnesium thin films covered with a layer of Pd absorb hydrogen at much higher pressures than bulk Mg. Such an effect was originally explained as a consequence of elastic clamping on Mg by the capping Pd layer. An alternative interpretation later suggested that the pressure increase could originate from simple alloying between Mg and Pd. Here we resolve this controversy by measuring the hydrogenation and dehydrogenation isotherms of Mg-Pd thin film alloys over a wide range of compositions. Our results disentangle the effects of elastic clamping and alloying and highlight the role of plastic deformations.

Published
2018
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42. Unveiling Nanoscale Compositional and Structural Heterogeneities of Highly Textured Mg0.7Ti0.3HyThin Films

Author

Kim, Hyunjeong, Schreuders, Herman, Sakaki, Kouji, Asano, Kohta, Nakamura, Yumiko, Maejima, Naoyuki, Machida, Akihiko, Watanuki, Tetsu, and Dam, Bernard

Abstract

Thin films often exhibit fascinating properties, but the understanding of the underlying mechanism behind such properties is not simple. This is partially because of the limited structural information available. The hurdle in obtaining such information is especially high for textured thin films such as Mg-rich MgxTi1–x, a promising switchable smart coating material. Although these metastable thin films are seen as solid solution alloys by conventional crystallographic methods, their hydrogen-induced optical transition is hardly understood by a solid solution model. In this study, we collect atomic pair distribution function (PDF) data for a Mg0.7Ti0.3Hythin film in situ on hydrogenation and successfully resolve TiH2clusters of an average size of 30 Å embedded in the Mg matrix. This supports the chemically segregated model previously proposed for this system. We also observe the emergence of a previously unknown intermediate face-centered tetragonal phase during hydrogenation of the Mg matrix. This phase appears between Mg and MgH2to reduce lattice mismatch, thereby preventing pulverization and facilitating rapid hydrogen uptake. This work may shed new light on the hydrogen-induced properties of Mg-rich MgxTi1–xthin films.

Published
2020
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44. Searching for Ti-clusters in Mg0.7Ti0.3 thin film

Author

Kim, Hyunjeong, primary, Asano, Kohta, additional, Sakaki, Kouji, additional, Nakamura, Yumiko, additional, Machida, Akihiko, additional, Maejima, Naoyuki, additional, Watanuki, Tetsu, additional, Schreuders, Herman, additional, and Dam, Bernard, additional

Published
2016
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46. Metallurgical Synthesis of Mg2FexSi1–xHydride: Destabilization of Mg2FeH6Nanostructured in Templated Mg2Si

Author

Asano, Kohta, Kim, Hyunjeong, Sakaki, Kouji, Nakamura, Yumiko, Wang, Yongming, Isobe, Shigehito, Doi, Masaaki, Fujita, Asaya, Maejima, Naoyuki, Machida, Akihiko, Watanuki, Tetsu, Westerwaal, Ruud J., Schreuders, Herman, and Dam, Bernard

Abstract

Magnesium-based transition-metal hydrides are attractive hydrogen energy materials because of their relatively high gravimetric and volumetric hydrogen storage capacities combined with low material costs. However, most of them are too stable to release the hydrogen under moderate conditions. Here we synthesize the hydride of Mg2FexSi1–x, which consists of Mg2FeH6and Mg2Si with the same cubic structure. For silicon-rich hydrides (x< 0.5), mostly the Mg2Si phase is observed by X-ray diffraction, and Mössbauer spectroscopy indicates the formation of an octahedral FeH6unit. Transmission electron microscopy measurements indicate that Mg2FeH6domains are nanometer-sized and embedded in a Mg2Si matrix. This synthesized metallographic structure leads to distortion of the Mg2FeH6lattice, resulting in thermal destabilization. Our results indicate that nanometer-sized magnesium-based transition-metal hydrides can be formed into a matrix-forced organization induced by the hydrogenation of nonequilibrium Mg–Fe–Si composites. In this way, the thermodynamics of hydrogen absorption and desorption can be tuned, which allows for the development of lightweight and inexpensive hydrogen storage materials.

Published
2020
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47. Destabilization of Mg Hydride by Self-Organized Nanoclusters in the Immiscible Mg-Ti System

Author

Asano, Kohta, Westerwaal, Ruud J., Anastasopol, Anca, Mooij, Lennard P. A., Boelsma, Christiaan, Ngene, Peter, Schreuders, Herman, Eijt, Stephan W. H., Dam, Bernard, Asano, Kohta, Westerwaal, Ruud J., Anastasopol, Anca, Mooij, Lennard P. A., Boelsma, Christiaan, Ngene, Peter, Schreuders, Herman, Eijt, Stephan W. H., and Dam, Bernard

Abstract

Mg is an attractive hydrogen storage material not only because of its high gravimetric and volumetric hydrogen capacities but also because of it low material costs. However, the hydride of MgH2 is too stable to release hydrogen under moderate conditions. We demonstrate that the formation of nanometer-sized clusters of Mg reduces the stability of MgH2 by the interface energy effect in the immiscible Mg-Ti system. Ti-rich MgxTi1-x (x < 0.5) thin films deposited by magnetron sputtering have a hexagonal close packed (HCP) structure, which forms a face-centered cubic (FCC) hydride phase upon hydrogenation. Positron Doppler broadening depth profiling demonstrates that after hydrogenation, nanometer-sized MgH2 clusters are formed which are coherently embedded in an FCC TiH2 matrix. The P (pressure)-T (optical transmission) isotherms measured by hydrogenography show that these MgH2 clusters are destabilized. This indicates that the formation of nanometer-sized Mg allows for the development of a lightweight and cheap hydrogen storage material with a lower desorption temperature.

Published
2015
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50. The effect of microstructure on the hydrogenation of Mg/Fe thin film multilayers

Author

Mooij, Lennard, Perkisas, Tyche, Pálsson, Gunnar, Schreuders, Herman, Wolff, Max, Hjörvarsson, Björgvin, Bals, Sara, Dam, Bernard, Mooij, Lennard, Perkisas, Tyche, Pálsson, Gunnar, Schreuders, Herman, Wolff, Max, Hjörvarsson, Björgvin, Bals, Sara, and Dam, Bernard

Abstract

Nanoconfined magnesium hydride can be simultaneously protected and thermodynamically destabilized when interfaced with materials such as Ti and Fe. We study the hydrogenation of thin layers of Mg (<14 nm) nanoconfined in one dimension within thin film Fe/Mg/Fe/Pd multilayers by the optical technique Hydrogenography. The hydrogenation of nanosized magnesium layers in Fe/Mg/Fe multilayers surprisingly shows the presence of multiple plateau pressures, whose nature is thickness dependent. In contrast, hydrogen desorption occurs via a single plateau which does not depend on the Mg layer thickness. From structural and morphological analyses with X-ray diffraction/reflectometry and cross-section TEM, we find that the Mg layer roughness is large when deposited on Fe and furthermore contains high-angle grain boundaries (GB's). When grown on Ti, the Mg layer roughness is low and no high-angle GB's are detected. From a Ti/Mg/Fe multilayer, in which the Mg layer is flat and has little or no GB's, we conclude that MgH2 is indeed destabilized by the interface with Fe. In this case, both the ab- and desorption plateau pressures are increased by a factor two compared to the hydrogenation of Mg within Ti/Mg/Ti multilayers. We hypothesize that the GB's in the Fe/Mg/Fe multilayer act as diffusion pathways for Pd, which is known to greatly alter the hydrogenation behavior of Mg when the two materials share an interface.

Published
2014
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