title: Two-Dimensional Rectangular and Honeycomb Lattices of NbN: Emergence of Piezoelectric and Photocatalytic Properties at Nanoscale.
abstract: Using first-principles calculations, we predict that monolayered honeycomb and rectangular two-dimensional (2D) lattice forms of NbN are metastable and naturally derivable from different orientations of its rocksalt structure. While the rectangular form is shown to retain the metallic and superconducting (SC) properties of the bulk, spectacularly contrasting properties emerge in the honeycomb form of NbN: it exhibits (a) semiconducting electronic structure suitable for valleytronics and photocatalysis of water splitting, (b) piezoelectricity with a spontaneous polarization originating from a rare sd(2)-sp(2) type hybridization, and (c) a wide gap in its phonon spectrum making it suitable for use in hot carrier solar cells. Our work demonstrates how low coordination numbers and associated strong bonding stabilize 2D nanoforms of covalently bonded solids and introduce novel functionalities of technological importance.
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560 064, India.
authors.forename: Shashwat
authors.initials: S
authors.lastname: Anand
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560 064, India.
authors.forename: Krishnamohan
authors.initials: K
authors.lastname: Thekkepat
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560 064, India.
authors.forename: Umesh V
authors.initials: UV
authors.lastname: Waghmare
mesh_terms: D002384:Catalysis; D004560:Electricity; D008027:Light; D008670:Metals / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D012666:Semiconductors
chemical_list: D008670:Metals
keywords: Two-dimensional materials; first-principles; photocatalysis; photovoltaics; piezoelectricity; superconductivity