Activation of Lattice Oxygen in Ceria by Plasma Exsolution of MoOx with Atomic Dispersion for NOx Abatement

The rational control of lattice oxygen activity at the metal oxide surface remains a great challenge. Herein, an O2 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 × 10–3 s–1 at 200 °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 4dx2–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 O2 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.