The Study On The Adsorption Performence Of Toxic Gases On Two-dimentional Germanium Selenide Contain Nig Point Defects

The single-layered germanium selenide is a two-dimensional monoatomic film with a phosphorene-like structure.It has been recently successfuilly prepared by combining mechanical peeling and laser thinning techniques.Single-layered germanium selenide has exotic optical properties and applications for direct bandgap semiconductors.It has important application prospects in photoelectrons,solar cells,et al.Studies have shown that a single layer of germanium selenide is a good detection and catalyst for toxic gas molecules(NH3,SO2 and NO2).Adsorption of these poisonous gas molecules on a single layer of germanium selenide changes its electronic structure and photoelectric properties.On this basis,we discussed the stability,density of states and work function of the system caused by point defects in germanium selenide,including vacancies,anti-sites,and P atom substitution doping.Based on first-principles calculations,considering the van der Waals interactions,a single layer germanium selenide system with point defects engineering and atomic doping was studied.The adsorption properties of the systems composed by defective germanium selenide and toxic gases(NH3,SO2 and NO2)are studied,including the microstructure,stability,and optoelectronic properties.The main conclusions are obtained as following:(1)In the aspect of microstructure,it is found that the point defects and atomic doping have little impact on its microstructure in the atomic doping system.The doping atoms and the nearest atoms form covalent bonds.The distances between toxic gas molecules(NH3,SO2 and NO2)and single-layered germanium selenide with point defects range from 2 A to 3.2 A.In the aspect of stability,the formation of anionic/cationic(Ge/Se)point defect system is found more easily than the anion defect.Comparing the anti-site doping and the P atom substitution,it is found that the Se atoms substituted Ge sites in GeSe monolayer has lower binding energy.(2)In the aspect of adsorption performance,it is found that the single-layered GeSe substrate with defects has stronger adsorption capacity for toxic gas molecules(NH3,SO2 and NO2)than that in the prestine single-layered GeSe.In addition,through the analysis of the bonding between gas molecules and conbined with the DOS analysis,it was found that all the adsorption system are chemical adsorption,except the relatively weak physical adsorption in the case of NH3 molecules adsorption.The adsorption energy of toxic gas molecules(NH3,SO2 and NO2)on the GeSe substrate with Se atom substitution on Ge site is lowest.It was found that the density of electronic states near the fermi surface is very sensitive to the toxic gas molecules adsorption on the point defects in single layer GeSe.The tuning of the electronic properties by toxic gas molecules(NH3,SO2 and NO2)is useful for its application of sensor.(3)It was found that the studied point defects engineering can tune the work function of GeSe monolayer by adsorption toxic gas molecules(NH3,SO2,and NO2).Comparing with the work functions of the studied different defect containning single-layer GeSe,it is found that the adsorption of NH3 on the point defect containning GeSe monolayer reduces the work function,while the adsorptions of SO2 and NO2 increase the work function,respectively.