High stability and superior catalytic reactivity of nitrogen-doped graphene supporting Pt nanoparticles as a catalyst for the oxygen reduction reaction: a density functional theory study

We investigated the structural and electronic properties of Pt-13 nanoparticles on various nitrogen (N)-doped graphene and their interaction with O by density functional theory (DFT) calculations. The results revealed that the N-doping can greatly enhance the binding strength of Pt-13 nanoparticles on the graphene surface, thus ensuring their high stability. For N-C doping (N atoms directly substituting for C atoms), the enhanced binding strength of the Pt-13 cluster is attributed to the activation of the carbon atoms around the N-dopant, while the strong hybridization of the d states of the Pt-13 cluster with the sp(2) dangling bonds of the N atoms in defective N-doped graphenes contributes to the strong adsorption. Moreover, a certain amount of electrons are transferred from Pt-13 to the substrate accompanied by a substantial downshift of the Pt-13 d-band center, thus greatly weakening the interaction of O on these composites: the adsorption energy of O is reduced from -3.700 eV on freestanding Pt-13 nanoparticles to -1.762, -1.723, and -1.507 eV on deposited Pt-13 ones on N-C, 3NV, and 4ND structures, respectively. Hence, it is expected that N-doped graphene supported Pt nanoparticles exhibit super catalytic reactivity in the ORR.