Effect of doping and vacancy defects on the adsorption of CO on graphene

The adsorption behavior of CO molecules on graphene has been computationally studied by using the first principles method. Results show that only weak physical adsorption is formed between CO and intrinsic or vacancy defected graphene. However, doping Mn atoms on graphene significantly increases the adsorption energy and charge density between graphene and CO. After the adsorption of CO molecules, impurity band appears in the band structure near the Fermi level of graphene and the total density of states of the adsorption system shifts, which enhances the electrical conductivity of the system. Therefore, doping Mn atoms can greatly improve the adsorption performance of CO molecules on graphene and result in strong chemisorption. Results also show that the adsorption effect of CO on Mn-doped intrinsic graphene is stronger than on Mn-doped vacancy defected graphene. Mn-doped intrinsic graphene is more suitable for making high-performance CO gas sensors.