Oxygen and Electron Storage Effects in W‐Modified Ceria Catalysts for Ammonia Conversion

Abstract

Tungsten‐modified CeO2 is an excellent catalyst for the catalytic conversion of ammonia. However, the geometric and electronic properties of this catalyst and the detailed reaction mechanisms are not well understood. In this work, the potential configurations of various monomer tungsten oxides supported on the CeO2(111) surface (WOX(x = 0–4)/CeO2(111)) are systematically studied and their relative stabilities are evaluated by using on‐site Coulomb interaction corrected density functional theory calculations. Their performances are also investigated in enhancing the catalytic efficiency of NH3 adsorption and activation. It is found that the WOx clusters can always form tetrahedron‐like structures on the CeO2(111) surface, and the CeO2(111) can exhibit both oxygen‐ and electron‐storage roles to help the WOX maintain such tetrahedron‐like WO4 structures and keep the W species at the highest 6+ state. Moreover, the flexibility of the tetrahedral WO4 structure leads to the preferential heterolytic NH3 dissociation at the WO sites, forming stable WNH2 and OH species. This study deepens the understanding of the unique oxygen‐ and electron‐storage effects of the CeO2 support, it also provides valuable insights into the extraordinary catalytic properties of the W‐modified CeO2 in NH3 conversion, paving the way for the rational design of more efficient CeO2‐based NH3 treatment catalysts.