Lattice Oxygen Activation Triggered by Ultrasonic Shock Significantly Improves NO Selective Catalytic Reduction

Abstract

The precise regulation of lattice oxygen is crucial for many redox reactions, but it still remains a formidable challenge. Herein, we reported a facile strategy to induce generation of bulk phase defects in hematite (α-Fe₂O₃) by ultrasonic treatment, thus achieving exclusive lattice oxygen activation without additional alternation of surface adsorbed oxygen species. This kind of unique lattice oxygen activation afforded negligible disturbance of NH₃ adsorption but significant influence on NO₂ generation via accelerated oxygen diffusion, resulting in enhanced activity contribution from the Fast-SCR reaction pathway. Particularly, the generation of bulk-phase defects was also found to be conducive to create thermally instable and chemically reactive surface nitrate species, which played a decisive role in activating NO reactant. Accordingly, a triple increment in the deNO_x performance of the α-Fe₂O₃ catalyst for the reaction of selective catalytic reduction of NO with NH₃ (NH₃–SCR) was achieved.