Mechanism investigations on CO oxidation catalyzed by Fe-doped graphene: A theoretical study

Abstract

The reaction mechanism in heterogeneous catalysis which is involving O2 or atomic oxygen has been dicussed intensely because the spin change of O2 molecule and atomic O during the reaction. To understand the mechanism of CO oxidation is key for design of advanced materials. Here we demonstrate spin conversion occurs in the path of CO oxiation on Fe-doped graphene (Fe-Gr) with or without electric field according to our DFT investigations. Moreover, the reations proceed via the similar favourable spin state along the pathways both without and with the considered electric field. Additionally, the negative eletric field applied is revealed to promote CO oxidation due to its improving activation of O-O bond in O2, but also induce a competition between the atomic O removal via CO + O* → CO2 for the catalyst regeneration and the carbonate-like species formation via CO2 + O* →CO3* when the negative electric field stronger than −0.25 V/Å. Therefore, a more appropriate for CO oxidation on Fe-Gr is proposed as evidenced under −0.10 V/Å with a lower determined reaction barrier of 0.62 eV at 298.15 K and expelling the carbonate-like species formation. These findings offer a new view of CO oxidation on the doped graphene.