基于密度泛函理论研究掺杂Pd石墨烯吸附O2及CO

基于第一性原理的密度泛函理论研究了单个O₂和CO气体分子吸附于本征石墨烯和掺杂钯(Pd)的石墨烯的体系, 通过石墨烯掺Pd前后气体分子的吸附能、电荷转移及能带和态密度的计算, 发现掺Pd后气体分子吸附能和电荷转移显著增大, 这是由于Pd的掺杂, 在本征石墨烯能带中引入了杂质能级, 增强了石墨烯和吸附气体分子间的相互作用; 氧化性气体O₂和还原性气体CO吸附对石墨烯体系能带结构和态密度的影响明显不同, 本征石墨烯吸附O₂后, 费米能级附近态密度变大, 掺Pd后在一定程度变小; 吸附还原性的CO后, 石墨烯费米能级附近态密度几乎没有改变, 表明掺杂Pd不会影响石墨烯对CO的气体灵敏度, 但由于CO对石墨烯的吸附能增大, 可以提高石墨烯对还原性气体的气敏响应速度.

Density functional theory studies of O2 and CO adsorption on the graphene doped with Pd

Based on density functional theory, the single O₂ and CO adsorption on pristine and palladium (Pd) doped graphene are studied using first-principles calculations. By calculating the system adsorption energy, charge transfer, band structure and density of states (DOS), we find that compared with O₂ and CO adsorbed on the pristine graphene, the Pd doped systems have high adsorption energies and large charge transfers. The reason is that the new energy levels which are brought into pristine graphene by the dopant Pd strengthened the interaction between graphene and the adsorbed gas molecule. Oxidizing gas O₂ and reducing gas CO have obviously different effects on band structure and DOS of graphene. The DOS near the Fermi level of graphene has great change after adsorbing O₂ and the change becomes smaller when O₂ is adsorbed on Pd doped graphene, while there is almost no change in DOS when graphene adsorbs CO, which indicates that doping Pd on graphene adsorbing CO will not enhance the gas sensitivity. However, the adsorption energy increases, which can improve the gas sensing response speed when graphene adsorbs reducing gas.