Fig. 4. Possible reaction mechanism for the Ni3Nb catalyst. (a) Nanophase-separated Ni3Nb catalyst in the exhaust atmosphere. Both the Ni surface and metal/oxide interface perimeter are occupied by dissociative NO admolecules. (b) Oxygen vacancies on the NbOx matrix adopt nitrogen adatoms. The nitrogen atoms are donated back to the metal/oxide perimeter to generate N2 molecules. (c) CO molecules are adsorbed at the free perimeter and (d) oxidized to CO2 by the neighbouring oxygen adatoms.
