Enhanced hydrogen permeability of hafnium nitride nanocrystalline membranes by interfacial hydride conduction

Kura, Chiharu; Fujimoto, Sanji; Kunisada, Yuji; Kowalski, Damian; Tsuji, Etsushi; Chen, Zhu; Habazaki, H.; Aoki, Yoshitaka

doi:10.1039/c7ta10253d

Cited by 19 publications

(17 citation statements)

References 70 publications

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“…This peculiar behavior was observed and quantitatively described in HfN [ 12 ], used as a component of multilayer membranes for the isotope separation of hydrogen, and in TiN [ 13 , 14 , 15 ], and confirmed by DFT (Density Functional Theory) calculations conducted on TiN x . The most recent studies verified H permeability experimentally; it was attributed to the formation of Ti-H terminal groups on the surface of crystallites in nanocrystalline matrices and the subsequent diffusion of H - through the boundary-grain interphase.…”

Section: Introductionmentioning

confidence: 59%

“…Moreover, the hydrogen permeation flux of stoichiometric TiN is smaller than that of slightly N-deficient samples (x ~ 0.7) at T < 100 °C. From the literature, TiN-based membranes are characterized by a pure cubic Fm-3m crystallographic phase with a (111) preferential orientation, and hydrogen permeability is remarkably enhanced by decreasing the grain size down to about 15 nm [ 12 , 14 ]. From Table 2 and Table 3 , samples TiN1, TiN2, and TiN3 are sub stoichiometric and have small grains but they contain the Ti-rich hexagonal crystalline structure too.…”

Section: Resultsmentioning

confidence: 99%

“…Then, one test sample was successfully grown on a porous alumina substrate. Commercial substrates were supplied by Cobra Technologies BV (Rijssen, The Netherlands) [ 12 , 14 ]. The substrates are discs with a 25 mm diameter, a 2 mm thickness, consisting of a support of α-Al 2 O 3 and having an 80 nm controlled porosity; they are polished (Ra < 0.1 µm) and coated on one side with a layer of γ-Al 2 O 3 that has a nanometric porosity in the range of 3 to 5 nm.…”

Section: Methodsmentioning

confidence: 99%

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Production Strategies of TiNx Coatings via Reactive High Power Impulse Magnetron Sputtering for Selective H2 Separation

et al. 2021

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This scientific work aims to optimize the preparation of titanium nitride coatings for selective H2 separation using the Reactive High Power Impulse Magnetron Sputtering technology (RHiPIMS). Currently, nitride-based thin films are considered promising membranes for hydrogen. The first series of TiNx/Si test samples were developed while changing the reactive gas percentage (N2%) during the process. Obtained coatings were extensively characterized in terms of morphology, composition, and microstructure. A 500 nm thick, dense TiNx coating was then deposited on a porous alumina substrate and widely investigated. Moreover, the as-prepared TiNx films were heat-treated in an atmosphere containing hydrogen in order to prove their chemical and structural stability; which revealed to be promising. This study highlighted how the RHiPIMS method permits fine control of the grown layer’s stoichiometry and microstructure. Moreover, it pointed out the need for a protective layer to prevent surface oxidation of the nitride membrane by air and the necessity to deepen the study of TiNx/alumina interface in order to improve film/substrate adhesion.

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Section: Introductionmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Production Strategies of TiNx Coatings via Reactive High Power Impulse Magnetron Sputtering for Selective H2 Separation

et al. 2021

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“…This interpretation is supported by the broad Raman peaks at 930 and 1250 cm −1 in Fig. 3d that may be assigned to vibrations related to Hf-N species 36,37 . There is also a broad shoulder in the N 1 s region <400 eV that we assign to nitride-like nitrogen since peaks from metal nitrides occur near 397 eV.…”

Section: Resultsmentioning

confidence: 52%

Nitrogen-plasma treated hafnium oxyhydroxide as an efficient acid-stable electrocatalyst for hydrogen evolution and oxidation reactions

et al. 2019

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Development of earth-abundant electrocatalysts for hydrogen evolution and oxidation reactions in strong acids represents a great challenge for developing high efficiency, durable, and cost effective electrolyzers and fuel cells. We report herein that hafnium oxyhydroxide with incorporated nitrogen by treatment using an atmospheric nitrogen plasma demonstrates high catalytic activity and stability for both hydrogen evolution and oxidation reactions in strong acidic media using earth-abundant materials. The observed properties are especially important for unitized regenerative fuel cells using polymer electrolyte membranes. Our results indicate that nitrogen-modified hafnium oxyhydroxide could be a true alternative for platinum as an active and stable electrocatalyst, and furthermore that nitrogen plasma treatment may be useful in activating other non-conductive materials to form new active electrocatalysts.

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“…The hafnium nitrides are an interesting class of ceramics that have shown promise in a diversity of applications that include high temperature coatings, 1,2 uses in electronics, 3 solar cells, 4 and even hydrogen storage 5 . Despite decades of research and the wide applications of these materials, the stability of the phases that comprise the hafnium‐nitrogen (Hf‐N) system are still debated 6‐10 .…”

Section: Introductionmentioning

confidence: 99%

A computational examination of the zeta and eta phases in the hafnium nitrides

Weinberger

Thompson

2020

J Am Ceram Soc

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The hafnium nitrides are an interesting class of ceramics that have shown promise in a diversity of applications that include high temperature coatings, 1,2 uses in electronics, 3 solar cells, 4 and even hydrogen storage. 5 Despite decades of research and the wide applications of these materials, the stability of the phases that comprise the hafnium-nitrogen (Hf-N) system are still debated. 6-10 For the advancement of these materials in these and other emerging technologies, it is particularly important to concretely establish and understand the equilibrium phase diagram in the Hf-N system. One of the earliest phase equilibrium diagrams for the Hf-N system was described by Toth. 11 As with many ultrahigh temperature ceramics, this system has a rocksalt phase, δ-HfN, which can be found at nitrogen concentrations between 39 and 52 at.%, depending on temperature. In contrast to the transition metal carbides which also form the rocksalt structure, 12,13 δ-HfN is able to retain the rocksalt structure for a modest nonmetal-rich composition. 7,10 Thus, δ-HfN can be regarded as a strongly nonstoichiometric compound. With the depletion of nitrogen, Rudy 14 originally reported two specific subnitride phases, the-Hf 3 N 2−x (originally called the ε-Hf 3 N 2) and ζ-Hf 4 N 3−x phases. The former eta phase was identified to have a 9R metal atom stacking sequence, that is (hhc) 3 or ABABCBCAC. The latter zeta phase has a similar metal atom stacking sequence given as (hhcc) 3 or ABABCACABCBC, which is equivalent to the structure identified by Yvon and Parthe as the ζ-V 4 C 3−x phase. 15,16 The compositions of the eta and zeta phases were only identified for single samples at chemistries of HfN 0.56 and HfN 0.65 , respectively. However, Rudy was not able to identify either a composition range for the phases (and thus they were assumed to be line compounds) nor establish if or how much the nitrogen atoms were ordered in either structure. Rudy further identified the upper decomposition temperatures for these respective phases to be approximately 2000°C (eta) and 2300°C (zeta).

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Enhanced hydrogen permeability of hafnium nitride nanocrystalline membranes by interfacial hydride conduction

Abstract: Hydrogen permeability based on mixed hydride ion electron conduction was demonstrated for hafnium nitride HfNx (film thickness of 100–500 nm, x = 0.8 and 1.0) nanocrystalline membranes.

Cited by 19 publications

References 70 publications

Production Strategies of TiNx Coatings via Reactive High Power Impulse Magnetron Sputtering for Selective H2 Separation

Production Strategies of TiNx Coatings via Reactive High Power Impulse Magnetron Sputtering for Selective H2 Separation

Nitrogen-plasma treated hafnium oxyhydroxide as an efficient acid-stable electrocatalyst for hydrogen evolution and oxidation reactions

A computational examination of the zeta and eta phases in the hafnium nitrides

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