First-principles Study Of Hydrogen Storage Properties Of Graphene

Hydrogen energy is is a new type of clean energy which is worth developing at present,because of the hydrogen from water,the hydrogen on earth abundant hydrogen storage is relatively high,its combustion product is water,will not cause environmental pollution,it is a kind of environmental sustainable clean energy.In recent years,many research scholars have done a lot of research on hydrogen energy,and found that the storage and transportation of hydrogen is one of the key factors of hydrogen energy utilization,because of the traditional skills and hydrogen storage materials has low hydrogen storage capacity,so we can not meet the present stage of hydrogen energy utilization demand,we need to develop new hydrogen storage materials.In 2004 a two-dimensional graphene structure was found which has a lot of excellent performance,it has large specific surface area and high strength,is a kind of ideal material for hydrogen storage,but the study found that the hydrogen storage capacity of pure graphene is low,It is necessary to modify the graphene to improve its hydrogen storage capacity.Based on the above research background,In this paper,we carried out first-principles calculations based on density functio naltheor to study the effects of metal elements of aluminium and calcium modified graphene on the hydrogen storage properties;due to the presence of defects more or less in the actual production of graphene prepared,we on the defects of graphene model for the adsorption of hydrogen molecules the calculation for the experiment,the preparation of graphene provides a theoretical basis for hydrogen storage materials.The adsorption of hydrogen on aluminum modified graphene is mainly physical adsorption,and each aluminum atom can adsorb up to 6 hydrogen molecules,and its adsorption is in-0.2eV——0.6eV/H2,the reversible hydrogen storage capacity of graphene is very good,indicating that aluminum modified graphene is a promising material for hydrogen storage.The modification of Ca greatly improve the hydrogen storage capacity of graphene,the adsorption of hydrogen molecule system both physical adsorption and chemical adsorption,which is dominated by physical adsorption;calcium modified graphene adsorbed hydrogen molecules,hydrogen molecules appear when high density,molecular hydrogen spillover phenomenon,when the surrounding a calcium atomic adsorption 4 hydrogen molecules,the lowest average adsorption of hydrogen molecule graphene,when 4 hydrogen molecule adsorption structure is the most stable when the adsorption of 5 hydrogen molecules,the average adsorption of calcium modified graphene to the absolute value is too large,is not conducive to the release of hydrogen molecules,6 hydrogen adsorption molecular adsorption,can quickly become smaller,We found that the hydrogen molecule spilled.Graphene defects can improve the hydrogen storage capacity of graphene,the adsorption of hydrogen molecules are both physical adsorption and chemical adsorption,which is dominated by physical adsorption;The double vacancy defect graphene has better hydrogen storage ability compared with single vacancy defect graphene.