Strikingly Facile Cleavage of N–H/N–O Bonds Induced by Surface Frustrated Lewis Pair on CeO<sub>2</sub>(110) to Boost NO Reduction by NH<sub>3</sub>
Shan Yang, Siqing Cheng, Fang Xu, Xueqing Liu, Xuechen Zhu, Hao Liu, Fudong Liu, Dezhan Chen, Chuanzhi Sun
Abstract
Ceria with surface solid frustrated Lewis pairs (FLPs), formed by regulating oxygen vacancies, demonstrate remarkable ability in activating small molecules. In this work, we extended the application of FLPs on CeO 2 (110) to the selective catalytic reduction of NO by NH 3 (NH 3 –SCR), finding a notable enhancement in performance compared to ordinary CeO 2 (110). Additionally, an innovative approach involving H 2 treatment was discovered to increase the number of FLPs, thereby further boosting the NH 3 –SCR efficiency. Typically, NH 3 –SCR on regular CeO 2 follows the Eley–Rideal (E–R) mechanism. However, density functional theory (DFT) calculations revealed a significant reduction in the energy barriers for the activation of N–O and N–H bonds under the Langmuir–Hinshelwood (L–H) mechanism with FLPs present. This transition shifted the reaction mechanism from the E–R pathway on regular R-CeO 2 to the L-H pathway on FLP-rich FR-CeO 2, as corroborated by the experimental findings. The practical application of FLPs was realized by loading MoO 3 onto FLP-rich FR-CeO 2, leveraging the synergistic effects of acidic sites and FLPs. This study provides profound insights into how FLPs facilitate N–H/N–O bond activation in small molecules, such as NH 3 and NO, offering a new paradigm for catalyst design based on catalytic mechanism research.