Effects of gas adsorption on the electronic properties of graphene nanoribbons

We have investigated the effects of O2 molecule gas adsorption on the electronic properties of semiconductor armchair hydrogenated edges graphene nanoribbons (AHEGN) via density functional theory as implemented in the code WIEN2k. The energy adsorption and electronic properties are calculated for different positions of O2. It is found that adsorption energy in the edges is lower than in the other positions. By increasing adsorption of gas concentration, the energy gap of AHEGN decreases and at a critical concentration a semiconducting-metallic phase transition takes place. This system could be used for detection of oxygen molecule gas.