A systematic, first-principles study of the structural preference and magnetic properties of mononitrides of the d-block metals

Hlynsson, Valtýr Freyr; Skúlason, Egill; Garden, Anna L.

doi:10.1016/j.jallcom.2014.02.153

Cited by 23 publications

(15 citation statements)

References 31 publications

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“…The structural optimization is considered converged when the forces in any direction on all moveable atoms are less than 0.01 eV/Å. A previous study showed several of the 3d mononitrides to be either antiferromagnetic (RS structure of VN, CrN, MnN, FeN and ZB structure of MnN) or ferromagnetic (ZB structure of VN, CrN) at their equilibrium lattice constants and as such are treated as spin-polarized [31]. The RPBE lattice constants are also taken from that study.…”

Section: Methodsmentioning

confidence: 99%

Transition Metal Nitride Catalysts for Electrochemical Reduction of Nitrogen to Ammonia at Ambient Conditions

Abghoui

Sklasson

2015

Procedia Computer Science

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Computational screening for catalysts that are stable, active and selective towards electrochemical reduction of nitrogen to ammonia at room temperature and ambient pressure is presented from a range of transition metal nitride surfaces. Density functional theory (DFT) calculations are used to study the thermochemistry of cathode reaction so as to construct the free energy profile and to predict the required onset potential via the Mars-van Krevelen mechanism. Stability of the surface vacancy as well as the poisoning possibility of these catalysts under operating conditions are also investigated towards catalyst engineering for sustainable ammonia formation. The most promising candidates turned out to be the (100) facets of rocksalt structure of VN, CrN, NbN and ZrN that should be able to form ammonia at -0.51 V, -0.76 V, -0.65 V and -0.76 V vs. SHE, respectively. Another interesting result of the current work is that for the introduced nitride candidates, hydrogen evolution is no longer the competing reaction; thus, high formation yield of ammonia is expected at low onset potentials.

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Section: Methodsmentioning

confidence: 99%

Transition Metal Nitride Catalysts for Electrochemical Reduction of Nitrogen to Ammonia at Ambient Conditions

Abghoui

Sklasson

2015

Procedia Computer Science

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“…Though theoretical works predict both ZBand RS-type structures for FeN and CoN, but under ambient temperature and pressure, the ZB-type structure is preferred [21]. The energy minima in the total energy-volume plots is lower in ZB, as compared to that in RS CoN [21,22,[37][38][39][40]. Under high pressure, a phase transition from ZB-to RS-type phase is expected at about 50 GPa in FeN [33] and about 40 GPa in CoN [22].…”

Section: Introductionmentioning

confidence: 94%

X-ray absorption spectroscopy study of cobalt mononitride thin films

et al. 2019

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We present a comprehensive study to resolve the debate about the structure of cobalt mononitride (CoN). In contradiction with theoretical predictions, experimentally CoN has been claimed to synthesize in a rock-salt (RS) and in a zincblende (ZB)-type structure under ambient pressure and temperature. Utilizing X-ray absorption near-edge spectroscopy (XANES) at Co and N K-edges and extended X-ray absorption fine structure (EXAFS) at Co K-edge, we investigated the structure of CoN in detail. The presence of a strong pre-edge feature at the Co K-edge and the absence of t 2 feature at the N K-edge indicate towards the tetrahedral coordination that is expected in the ZB-type structure of CoN. Theoretical simulations of XANES spectra unambiguously confirm the ZB-type structure in CoN. Also from EXAFS data, we found that CoN and Co-Co bond distances match well with ZB-CoN. Magnetic properties of CoN were examined using polarized neutron reflectivity and bulk magnetization measurements. It was found that CoN sample exhibits a paramagnetic behaviour as expected in ZB-CoN. Obtained results clearly demonstrate that CoN indeed crystalizes in the ZB-type structure, and the possibility of the RS-type CoN can be ruled out under ambient pressure and temperature. It is anticipated that the information about the structure of CoN can be utilized for its usage in emerging areas such as low-cost catalyst in oxygen and hydrogen evaluation reactions, high capacity anode in ion batteries and in photovoltaic applications.

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“…A previous study showed several of the 3d mononitrides to be either antiferromagnetic (RS VN, CrN, MnN, FeN and ZB MnN) or ferromagnetic (ZB VN, CrN) at their equilibrium lattice constants and as such are treated as spin-polarized. 56 The RPBE lattice constants are also taken from that study.…”

Section: Dft Calculationsmentioning

confidence: 99%

Enabling electrochemical reduction of nitrogen to ammonia at ambient conditions through rational catalyst design

Abghoui

Garden

Hlynsson

et al. 2015

Phys. Chem. Chem. Phys.

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275

272

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Commercial design of a sustainable route for on-site production of ammonia represents a potential economic and environmental breakthrough. In an analogous process to the naturally occurring enzymatic mechanism, synthesis of ammonia could be achieved in an electrochemical cell, in which electricity would be used to reduce atmospheric nitrogen and water into ammonia at ambient conditions. To date, such a process has not been realized due to slow kinetics and low faradaic efficiencies. Although progress has been made in this regard, at present there exists no device that can produce ammonia efficiently from air and water at room temperature and ambient pressure. In this work, a scheme is presented in which electronic structure calculations are used to screen for catalysts that are stable, active and selective towards N2 electro-reduction to ammonia, while at the same time suppressing the competing H2 evolution reaction. The scheme is applied to transition metal nitride catalysts. The most promising candidates are the (100) facets of the rocksalt structures of VN and ZrN, which show promise of producing ammonia in high yield at low onset potentials.

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A systematic, first-principles study of the structural preference and magnetic properties of mononitrides of the d-block metals

Cited by 23 publications

References 31 publications

Transition Metal Nitride Catalysts for Electrochemical Reduction of Nitrogen to Ammonia at Ambient Conditions

Transition Metal Nitride Catalysts for Electrochemical Reduction of Nitrogen to Ammonia at Ambient Conditions

X-ray absorption spectroscopy study of cobalt mononitride thin films

Enabling electrochemical reduction of nitrogen to ammonia at ambient conditions through rational catalyst design

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