Activation of Lattice Oxygen in Ceria by Plasma Exsolution of MoO _x with Atomic Dispersion for NO _x Abatement

The rational control of lattice oxygen activity at the metal oxide surface remains a great challenge. Herein, an O-2 plasma-assisted method was implemented to enable activation of lattice oxygen by exsolution of Mo from ceria lattice to the external surface with atomic dispersion. The obtained surface-loaded MoOx/CeO2 exhibited a superior turnover frequency of 1.33 x 10(-3) s(-1) at 200 degrees C for NOx abatement, far beyond the commercially available or reported NH3-SCR catalysts. The mechanism study revealed that the SCR reaction followed the Mars-van Krevelen pathway with dehydroxylation (release of the lattice oxygen) as the rate-determining step. The hybridization of Mo(4)dx (2 -y2) and O-2p orbitals gave rise to a unique 5-coordinated Mo site that facilitated the interfacial Mo-O-Ce lattice oxygen dehydration and subsequent nucleophilic O-2 filling, which accounted for its higher activity. This work highlights the great potential of plasma treatment to promote the lattice oxygen reactivity of ceria-supported atomically dispersed catalysts and provides valuable insights into the intrinsic understanding of the enhancement.