Synthesis, X-ray structure, density functional theory (DFT) study on electronic and optical properties of a novel 2D-polyoxovanadate anionic compound

A novel two-dimensional (2D) polyoxovanadate compound KV3O8 (1) has been synthesized and characterized crystallographically. The 2D anionic frameworks are built up from distorted VO6 octahedrons and VO5 square pyramids which are linked to one another via μ1-oxo, μ2-oxo and μ3-oxo atoms. The energy band structure, density of states (DOS), dielectric constant, refractive index and chemical bonds have been investigated by DFT method. The calculated results indicate that is a semi-conductor (band gap 2.1 eV). The character of the VO interactions is mainly covalent, while that of the K–O interactions is mainly ionic. The top of valence bands and the bottom of conduction bands are mostly built upon O 2p states mixed with V 3d states, and V 3d states mixed with O 2p states, respectively, via covalent P–O interactions. The nature of electronic absorption peak is assigned to be O(2p) → V(3d) charge transfer transition.