title: H2O incorporation in the phosphorene/a-SiO2interface: a first-principles study.
abstract: Based on first-principles calculations, we investigate (i) the energetic stability and electronic properties of single-layer phosphorene (SLP) adsorbed on an amorphous SiO2surface (SLP/a-SiO2), and (ii) the further incorporation of water molecules at the phosphorene/a-SiO2interface. In (i), we find that the phosphorene sheet binds to a-SiO2through van der Waals interactions, even in the presence of oxygen vacancies on the surface. The SLP/a-SiO2system presents a type-I band alignment, with the valence (conduction) band maximum (minimum) of the phosphorene lying within the energy gap of the a-SiO2substrate. The structure and the surface-potential corrugations promote the formation of electron-rich and electron-poor regions on the phosphorene sheet and at the SLP/a-SiO2interface. Such charge density puddles are strengthened by the presence of oxygen vacancies in a-SiO2. In (ii), because of the amorphous structure of the surface, we consider a number of plausible geometries for H2O embedded in the SLP/a-SiO2interface. There is an energetic preference for the formation of hydroxyl (OH) groups on the a-SiO2surface. Meanwhile, in the presence of oxygenated water or interstitial oxygen in the phosphorene sheet, we observe the formation of metastable OH bonded to the phosphorene, and the formation of energetically stable P-O-Si chemical bonds at the SLP/a-SiO2interface. Further x-ray absorption spectra simulations are performed, which aim to provide additional structural/electronic information on the oxygen atoms forming hydroxyl groups or P-O-Si chemical bonds at the interface region.
authors.affiliation: Departamento de Física, Universidade Federal do Espírito Santo, Vitória, ES, 29075-910, Brazil. Departamento de Ciências Exatas, Universidade Federal Fluminense, Volta Redonda, RJ, 27255-250, Brazil.
authors.forename: Wanderlã L
authors.initials: WL
authors.lastname: Scopel
authors.forename: Everson S
authors.initials: ES
authors.lastname: Souza
authors.forename: R H
authors.initials: RH
authors.lastname: Miwa