First-Principles Molecular Dynamics Study of the Heterogeneous Reduction of NO2 on Soot Surfaces

Abstract

The heterogeneous reduction of nitrogen dioxide on the surface of atmospheric soot particles was thoroughly investigated using pristine and defective graphene layers as simple models of the soot surface. The metadynamics method, based on Car−Parrinello molecular dynamics simulations, was used to reproduce atomistic details of the reaction paths, as well as to obtain estimations of the free energy barriers of the processes. The relative energies, geometries, and electronic structures of reactants, products, and intermediates observed during the trajectories were analyzed, and the catalytic activity of the carbon vacancies concerning the reduction of nitrogen dioxide is discussed. Our study predicts the release of nitrogen monoxide and the formation of stable nitro groups on the surface of soot particles in good agreement with experiments.