Silicon-Doped Graphene: An Effective and Metal-Free Catalyst for NO Reduction to N2O?

Density functional theory (DFT) calculations were performed on the NO reduction on the silicon (Si)-doped graphene. The results showed that monomeric NO dissociation is subject to a high barrier and large endothermicity and thus is unlikely to occur. In contrast, it was found that NO can easily be converted into N2O through a diner mechanism. In this process, a two-step mechanism was identified: (i) the coupling of two NO molecules into a (NO)(2) dimer, followed by (ii) the dissociation of (NO)(2) dimer into N2O + O-ad. In the energetically most favorable pathway, the trans-(NO)(2) dimer was shown to be a necessary intermediate with a total energy barrier of 0.464 eV. The catalytic reactivity of Si doped graphene to NO reduction was interpreted on the basis of the projected density of states and charge transfer.