First-principles study of C cites vacancy defects in water adsorbed Graphene

Abstract

 The electronic and magnetic properties of water adsorbed graphene (w_ad – G), single carbon (1C) atom vacancy defects in water adsorbed graphene (1C_atom-vacancy – w_ad – G) and double carbon (2C) atoms vacancy defects in water adsorbed graphene (2C_atom-vacancy – w_ad – G) materials are studied by first-principles calculations within the frame work of density functional theory (DFT) using computational tool Quantum ESPRESSO (QE) code. We have calculated the binding energy of w_ad – G, 1C_atom-vacancy – w_ad – G and 2C_atom-vacancy – w_ad – G materials, and then found that non-defects geometry is more compact than vacancy defects geometries. From band structure calculations, we found that w_ad – G is zero band gap semiconductor, but 1C_atom-vacancy – w_ad – G and, 2C_atom-vacancy – w_ad – G materials have metallic properties. Hence, zero band gap semiconductor changes to metallic nature due to C sites vacancy defects in its structures. We have investigated the magnetic properties of w_ad – G and its C sites vacancy defects materials by using Density of States (DOS) and Partial Density of States (PDOS) calculations. We found that w_ad – G is non- magnetic material. 1C atom vacancy defects in graphene surface of w_ad – G is induced magnetization by the re-bonding of two dangling bonds and acquiring significant magnetic moment (0.11 µB/ cell) through remaining unsaturated dangling bond. But, 2C atoms vacancy defects in graphene surface of w_ad – G induced low value of magnetic moment (+0.03 µB/ cell) than 1C atom vacancy defects in structure, which is due to no dangling bonds present in the structure. Therefore, non-magnetic, w_ad – G changes to magnetic, 1C_atom-vacancy – w_ad – G and, 2C_atom-vacancy – w_ad – G materials due to C sites vacancy defects in w_ad – G structure. The 2p orbital of carbon atoms has main contribution of magnetic moment in defects structures.