Defective structures and oxidation resistance of Janus AsP from first-principles prediction

1.Text Black phosphorus(BP)has sparked immense interests among two-dimensional(2D)nanomaterials since its first mechanical exfoliation from bulk BP in 2014[1].The atoms in BP are not distributed in the same plane,where the lone pair electrons of P atoms are highly reactive,and the structural anisotropy leads to many distinctive physical properties[2,3],like highly anisotropic effective masses and tunable electronic properties[4].Particularly,it possesses thickness-dependent direct bandgap values from 0.3 eV(bulk)to 1.5 eV(monolayer)[5].Owing to its unique structural and electronic properties,BP shows potential applications in electronic or optoelectronic devices[6-8].However,BP is reported to be unstable and easy to decompose in ambient conditions,which hinders its wide applications[9].Layered BP can rapidly transform into oxides,and further degrade into acids or salts within hours[10].Therefore,it is necessary to take some measures to inhibit the degradation of BP.