Mechanistic insights into the CO oxidation reaction catalyzed by P-coordinated metal-doped graphene: The roles of phosphorus and metal atom

Encouraged by the great promise of metal–nitrogen–carbon materials in catalyzing CO oxidation and the successfully introduction of metal–P species into carbon matrices in experiments, it is proposed metal–P species might also possess high reactivity to CO oxidation. Our DFT calculations of CO oxidation on MP4-Gr (M = Fe, Co, Ni) suggest that multi-molecules adsorption can be easily achieved with one CO on metal and one O2 on each P atom, resulting in the step-by step LH processes and then leave the atomic O on P which can be furhter removal via ER mechanism. Moreover, reactivities of the catalysts are determined by the ER process and the reactivity differences are closely related to the doping metal. Electronic structure analysis inidcates that decreasing d-band center position of metal from FeP4-Gr to CoP4-Gr to NiP4-Gr will weaken the CO adsorption on metal site and upshift the p-band center position of P atom, finnally weaken the O binding strength with P. Thus, higher reactivity is for CoP4-Gr and NiP4-Gr when compared to FeP4-Gr. This work highlights the possibility to manipulate the performance of catalyst in CO oxidation with incoorperating metal which would be helpful for design and implementation of promissing catalysts.