Influence of adsorbates on the electronic and magnetic properties of graphane with H-vacancy defects

The influence of adsorbates on the electronic and magnetic properties of graphane possessing the H-vacancy defects was investigated using the quantum-chemistry methods. We found that the H vacancies in graphane significantly improve its chemical reactivity to environment due to the unpaired electron left on the vacancy. Therefore, depending on the type of molecule adsorbed, the interaction between the adsorbate and the vacancy can occur with or without the formation of the bond. In case of the bond formation the unpaired electron supplied by the vacancy is removed and the electronic and magnetic properties of graphane become similar to that of pure defect-free graphane. Moreover, adsorption leads to degradation or vanishing of magnetism induced by the H vacancies in graphane, except in the case when the CO2 molecule is attached, which is found to generate localized state with the unpaired electron after bonding with the H vacancy. Stability of ferromagnetism induced by the CO2 molecules bound to the vacancies is found to be low. There are two reasons for low stability: localization of the spin density of the localized state entirely on adsorbate that minimize the interference of the spin tails of these states and the possibility of pairing of two neighboring CO2 molecules to C2O4.