First-principles investigation of LaMg2Ni and its hydrides

Weiqing Jiang,Xinglang Li,Xiaohua Mo,Yujie Chen

doi:10.1038/s41598-020-69113-9

Abstract

Using first-principles density functional theory calculations, the electronic structures of LaMg2Ni and its hydrides LaMg2NiH4.5 (intermediate phase) and LaMg2NiH7 (fully hydrogenated phase), as well as the H adsorption on LaMg2Ni (100) surface were investigated. For comparision, the atomic bonding characteristics of Co- and Pd-doped LaMg2Ni, LaMg2NiH4.5 and LaMg2NiH7 compounds were also studied. Our aim is to provide new insights into the hydrogenation of LaMg2Ni. The results show that the metallic intermediate hydride LaMg2NiH4.5 with Ni–H covalent bonds may act as the precursor state from the host compound LaMg2Ni to the full hydride LaMg2NiH7. Upon LaMg2Ni hydrogenation, the suppression of Mg–Ni and Ni–H interactions as well as the formation of La-H bonds favors for LaMg2Ni–H formation.

Highlights

IntroductionUsing first-principles density functional theory calculations, the electronic structures of LaMg2Ni and its hydrides L aMg2NiH4.5 (intermediate phase) and L aMg2NiH7 (fully hydrogenated phase), as well as the H adsorption on L aMg2Ni (100) surface were investigated
Using first-principles density functional theory calculations, the electronic structures of LaMg2Ni and its hydrides L aMg2NiH4.5 and L aMg2NiH7, as well as the H adsorption on L aMg2Ni (100) surface were investigated
Ouyang et al.[11] compared pure M g2Ni with LaMg2Ni on both thermodynamics and kinetics, and found that L aMg2Ni has a lower ΔH (− 51 kJ/mol H2) and ΔS (− 105 J/K mol H 2) for hydriding reaction, compared to the ΔH (− 65 kJ/mol H 2) and ΔS (− 122 J/K mol H2) for pure Mg2Ni, and costs less time to reach the saturated hydrogen capacity at lower temperature (1,100 s at 561 K for LaMg2Ni vs. 1,800 s at 573 K for Mg2Ni14)

Summary

Introduction

Using first-principles density functional theory calculations, the electronic structures of LaMg2Ni and its hydrides L aMg2NiH4.5 (intermediate phase) and L aMg2NiH7 (fully hydrogenated phase), as well as the H adsorption on L aMg2Ni (100) surface were investigated. Ouyang et al.[11] compared pure M g2Ni with LaMg2Ni on both thermodynamics and kinetics, and found that L aMg2Ni has a lower ΔH (− 51 kJ/mol H2) and ΔS (− 105 J/K mol H 2) for hydriding reaction, compared to the ΔH (− 65 kJ/mol H 2) and ΔS (− 122 J/K mol H2) for pure Mg2Ni, and costs less time to reach the saturated hydrogen capacity at lower temperature (1,100 s at 561 K for LaMg2Ni vs 1,800 s at 573 K for Mg2Ni14). To further understand the hydrogenation of L aMg2Ni, the hydrogen adsorption on LaMg2Ni (100) surface is studied

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Results

Conclusion