Adsorption Of BTA On Defected Copper Surfaces:A DFT Study

Copper and copper alloys are widely used in industrial production and daily life,which are prone to serious corrosion in oxygen,sulfur and ammonia containing environmrnt.Adding corrosion inhibitors is an effective and economical means of corrosion protection.Among inhibitors,benzotriazole(BTA)is an excellent copper corrosion inhibitor.The adsorption behavior of benzotriazole on copper surface has been studied from experiments and simulations,and the inhibition mechanism has also been identified.Most foreign experts and scholars are aimed to ideal copper,but there are various defects in actural copper or copper alloys.Little attention has been paid to the influence laws and mechanisms of these surface defects on corrosion inhibitors.In this paper,three kinds of copper surfaces(vacancy,dopping and grain boundary defect)are constructed by density functional theory(DFT)to study the influence rules and mechanisms of different defects on BTA.The following conclusions are drawn:The surface activity of vacancy Cu(111)surfaces increases with the decreasing of the coordination number.When BTA vertical adsorption on the surfaces,the smaller the coordination number is,the lager the adsorption energy is.And the smaller the coordination number is,the greater the electron density of the bonding is.The influence of vacancy defects on the adsorption can be explained by mean of energy level theory.Inhibitors can also be adsorbed on Cu(111)vacancy surface by tilting and cross layer adsorption and the adsorption energy is positively correlated with the bonding electron density.For doped Cu(111)surfaces,Zn and O doped has stronger adsorption activity than the Ni and S doped on negatively charged particle,respectively.Besides corrosive particles(O,S doped)strengthen the bonding between surfaces and BTA.BTA can only be adsorbed vertically on the metal doped copper surface,and the order of adsorption energy is Cu-Zn(Zn doped)> Cu-Cu(Ni doped)> Cu-Cu(Zn doped)> Cu-Ni(Ni doped).Contrastly,BTA can be adsorbed vertically and aslope on the corrosive particles doped surface.The inclined adsorption has greater adsorption energy than vertical adsorption.The essence of bonding is orbital hybridization,N s,p orbitals and Cu s,p,d orbitals.The larger the density of the bond,the greater the adsorption energy.Cu ?5(210)/[100] grain boundary surface has the atomic sparse area and atomic sparse dense areas,sparse area with longer bond and stronger atomic activity.BTA can be adsorbed vertically and parallelly on the grain boundary surface.The adsorption energy of horizontal adsorption is larger than that of vertical adsorption,and the grain boundarys' is larger than that of the ideal surfaces'.After adsorption,BTA can not only protect the grain boundary,but also increase the negative electricity in the non-boundary region,then protecting the non-boundary region from corrosion.The dipole moment analysis shows that the horizontal adsorption is more easily to form a stable inhibitor film than the vertical adsorption.After the systematic research,it is clear that the influence rules and mechanisms of the three defected surface on the adsorption of BTA.At the same time,we have a deeper understanding of the surface properties of different defects.