First-Principles Calculation Of Adsorption Of Pb²⁺,Cr²⁺,Cd²⁺ On Black Phosphorene

Black phosphorene has become the focus of research,as a new two-dimensional material.Black phosphorene has the unique honeycomb wrinkled structure,which makes it have the characteristics of large specific surface area,extremely high electron mobility,and excellent molecular adsorption energy.In the field of adsorption,black phosphorene has inherent advantages.In recent years,water pollution has become the primary problem in the process of environmental protection.Toxic heavy metal pollution will not only cause damage to the natural environment,but also have a huge destructive effect on human health.Pb²⁺,Cr²⁺,and Cd²⁺are common pollutants of the heavy metal pollution in water,which are not only difficult to degrade naturally over time,but also highly toxic and easily absorbed by organisms.Therefore,the removal of toxic metals from sewage and the development of powerful adsorption materials are crucial to ecological environment and health.In this paper,the CASTEP module of Material Studio was used to explore the adsorption behavior of pure,doped,defected,and stressed black phosphorene on Pb²⁺,Cr²⁺,and Cd²⁺.Through the calculation results of adsorption energy,density of state,charge transfer amount and bond level,the effects of doping,defect and stress on the adsorption properties of black phosphorene are discussed and analyzed.Studies show that:for Pb²⁺,pure black phosphorene has an adsorption effect on it.The adsorption energy of black phosphorene for Pb²⁺can be improved by doping B or the coexistence of P atom vacancy and B doping.Doping and P atom vacancy will cause impurities and defect energy levels in the band gap,which will enhance the ionic bond and covalent bond strength between Pb²⁺and black phosphorene surface bonding atoms,and improve the adsorption capacity of black phosphorene to Pb²⁺.Therefore,B-doped black phosphorene,black phosphorene with the coexistence of P atom vacancy and B doping can be used as Pb²⁺adsorption materials.However,applying stress on pure black phosphorene has a weak effect on adsorption of Pb²⁺,and the adsorption capacity of black phosphorene is not sensitive to stress,so stressed black phosphorene is not suitable as an adsorption material.For Cr²⁺,pure black phosphorene also has an adsorption effect on it.The adsorption energy of black phosphorene for Cr²⁺can be improved by doping S or P atom vacancy.Impurities and defect energy levels are introduced into the band gap,which enhance the ionic and covalent bonds between Cr²⁺and the bonding atoms on the surface of black phosphorene,and improve the ability of black phosphorene to adsorb Cr²⁺.Therefore,S-doped black phosphorene and P-vacancy black phosphorene can be used as adsorption materials for Cr²⁺.Since the adsorption capacity of black phosphorene is not sensitive to stress,applying stress cannot effectively improve the adsorption capacity of black phosphorene for Cr²⁺.So stressed black phosphorene is not suitable as an adsorption material.For Cd²⁺,pure black phosphorene cannot adsorb Cd²⁺,but its surface can be modified by doping and adding P atom vacancy to obtain the ability to adsorb Cd²⁺.The adsorption energy of black phosphorene for Cd²⁺can be improved by doping Si or the coexistence of P atom vacancy and Si doping.Impurities and defect levels exist in the band gap,which can enhance the strength of ionic and covalent bonds between Cd²⁺and bonding atoms.Therefore,Si-doped black phosphorene,black phosphorene with the coexistence of P-vacancy and Si doping can be used as Cd²⁺adsorption materials.However,applying stress on pure black phosphorene cannot make black phosphorene adsorb Cd²⁺,so stressed black phosphorene cannot be used as an adsorption material.