Structures and magnetic and electronic properties of the O 2 -adsorbed Fe 2 N clusters
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ORIGINAL RESEARCH
Structures and magnetic and electronic properties of the O2-adsorbed Fe2N clusters Zhen Zhao 1
&
Zhi Li 2
Received: 30 June 2020 / Accepted: 24 August 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The surface of iron nitrides prefers to be oxidized in the air, which reduces the cycling stability of the supercapacitors. The configurations and electronic and magnetic properties of the O2Fe2N clusters and reaction path from Fe2N + O2 to Fe2O + NO have been calculated by using PBE functional. An O2 molecule prefers to adsorb the Fe-Fe bridge of a Fe2N molecule from the vertical direction. For the ground-state O2Fe2N clusters, two separated O atoms are adsorbed on the Fe-N and Fe-Fe bridges of Fe2N molecule, respectively. The reaction process of Fe2N + O2 → Fe2O + NO undergoes O adsorption and migration. The internal electron transfer from 4s to 3d and 4p orbitals of Fe atoms in the O2Fe2N clusters becomes very important. O2 adsorption significantly decreases the spin of the Fe2N molecule. Keywords O2Fe2N clusters . First principles . Electronic properties . Reaction path
Introduction Nowadays, iron nitrides have developed into the most outstanding representatives of a novel electrode material for electrochemical storage device [1–4]. It is because that iron nitrides possess the similar electronic properties of the noble metals [5]. Considering various iron nitrides, Fe2N nanoparticles present obvious advantages (such as excellent electrical conductivity, low resistivity, and environmental compatibility) to the electrode materials [6, 7]. However, the thermal stability of iron nitrides is low. Usually carbon coating can block the oxidation reaction of Fe2N particles in the air and improve the mechanical properties of the inter-phase layer [8]. Nevertheless, once iron nitride nanoparticles are oxidized, the oxide layer will decrease electrical conductivity. The results bring a challenge to the preparation of iron nitride electrodes Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11224-020-01626-5) contains supplementary material, which is available to authorized users. * Zhen Zhao [email protected] 1
School of Chemistry and Life Science, Anshan Normal University, Anshan 114007, People’s Republic of China
2
School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, People’s Republic of China
[8]. It is very important to understand the mechanism of the interaction between Fe2N and O2 molecule. Oxygen reaction usually involves a process of O2 dissociation to two separated O atoms [9]. Whether this process occurs during the oxidation process of Fe2N and affects the charge distributions and magnetic properties of Fe2N is worth studying. The particles on the surfaces of iron nitride film are the spherical shapes and regarded as clusters containing certain crystallites [10]. Although the diameters of the Fe2N particles in carbon micro-boxes are less than 15 nm [11], the qua
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