Insight into Adsorption of C2H2 and H-2 on Doped Graphene with Nonmetallic Atom (N, P, S): A Density Functional Theory Study

摘要

A DFT investigation was performed to evaluate the structure, electronic properties of the doped graphene, and the adsorption behavior of C2H2 and H-2 on the graphene sheet. Two kinds of doping scenarios are considered, namely dopants into pristine graphene and vacancy graphene. It is observed that the doping energy is negative for dopant (N, P, S) into vacancy graphene at pyridinictype site, yet it is positive at graphitic-type site for pristine graphene. It could be inferred that the introducing process is exothermic reaction for defective graphene. Meanwhile, for the adsorption of C2H2 on the surface of defective graphene, we notice that C2H2 would prefer to be adsorbed at the top site of the doping atom and the adsorption energy increases with the introducing of dopants, indicating that the dopant would enhance the interaction between C2H2 and graphene. Regarding hydrogen molecule, the dopant has less promotion effect on the adsorption. Moreover, the graphene plays a role of electron donor while the gas molecule (C2H2/H-2) is the electron acceptor when it is adsorbed. For the co-adsorption, the C2H2 is privileged to interact with the graphene and the pre-adsorbed C2H2 on doped graphene would weaken the opportunity of the uptake of H-2 molecule. We anticipate that our results would provide information to design the optimized catalysts.