First-principles Study Of The Adsorption Properties Of Small Gas Molecules On The Surface Of Mg₃N₂ And Borophene

As the contradiction between energy supply and demand becomes increasing-ly prominent,the search for renewable and clean energy is imminent.Hydrogen is an inexhaustible source of clean energy.The development and use of hydrogen energy is of great significance to the sustainable development of human society.Hy-drogen storage is one of the most critical technical problems in the development of hydrogen energy.It is particularly important to find suitable hydrogen storage materials.The M-N-H?M refers to I-IV group elements and some transition met-al elements?complex hydrogen storage materials have attracted attention because of their high-capacity hydrogen storage properties and their reversibility.The new two-dimensional materials borophene is excellent because of its excellent ultra-high carrier rate,large specific surface area,low heat of adsorption,low activation energy,fast hydrogen absorption and release,and good cycle performance.The character-istics make it have great application value in the field of physical adsorption of hydrogen storage materials.The first principles density theory calculations have been performed to inves-tigate different Mg₃N₂surface and the corresponding properties of H₂adsorption.The calculation of surface energy present that Mg₃N₂?011?is the most stable surface.There are three main modes of chemical adsorption.The reaction energy barrier show that there is no competition among the three adsorption modes.The model of forming two NH is the easiest pathway,which have the lowest reaction energy barrier of 0.848 eV.The hydrogen storage properties of pristine_12-borophene and Li-decorated_12-borophene are systemically investigated by means of first-principles calculations based on density functional theory.The adsorption sites,adsorption energies,elec-tronic structures,and hydrogen storage performance of pristine_12-borophene/H₂and Li_-12-borophene/H₂systems are discussed in detail.The results show that H₂is dissociated into Two H atoms that are then chemisorbed on_12-borophene via strong covalent bonds.Then,we use Li atom to improve the hydrogen stor-age performance and modify the hydrogen storage capacity of_12-borophene.Our numerical calculation shows that Li_-12-borophene system can adsorb up to 7 H₂molecules;while 2Li_-12-borophene system can adsorb up to 14 H₂molecules and the hydrogen storage capacity up to 10.85wt.%.Borophene,a new two-dimensional material,was recently synthesized.The unique anisotropic structure and excellent properties of borophene have attracted considerable research interest.This paper presents a first-principles study of the adsorption of gas molecules?CO,CO₂,NH₃,NO,NO₂and CH₄?on borophene.The adsorption configurations,adsorption energies and electronic properties of the gas molecules absorpted on borophene are determined,and the mechanisms of the interactions between the gas molecules and borophene are evaluated.We find that CO,CO₂,NH₃,NO and NO₂are chemisorbed on borophene,while CH₄is ph-ysisorbed on borophene.Furthermore,our calculation also indicate that CO and CO₂are chemisorbed on borophene with moderate adsorption energy and NO,NO₂and NH₃are chemisorbed on borophene via strong covalent bonds.Moreover,CO is found as an electron donor,while CO₂an electron acceptor.The chemisorption of CO and CO₂on borophene increases the electrical conductivity,so It seems that borophene has the potential to be used in high-sensitivity CO and CO₂ gas sensors.