Activation of Lattice Oxygen in Ceria by Plasma Exsolution of MoO<sub><i>x</i></sub> with Atomic Dispersion for NO<sub><i>x</i></sub> Abatement
Yong Yin, Bingcheng Luo, Ye Sun, Pengfei Xie, Haifeng Xiong, Tianle Zhu, Xiang Li
Abstract
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 MoO x /CeO 2 exhibited a superior turnover frequency of 1.33 × 10 –3 s –1 at 200 °C for NO x abatement, far beyond the commercially available or reported NH 3 -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 4d x 2 – y 2 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.