Revealing active edge sites induced by oriented lattice bending of Co-CeO2 nanosheets for boosting auto-exhaust soot oxidation

Abstract

Herein, a series of Cox-CeO2 nanosheet catalysts were elaborately synthesized by a one-step hydrothermal method. The CeO2 microsphere with crossed nanosheets can improve the soot-catalyst contact efficiency and the lattice substitution of Co ions for cerium sites in CeO2 results in the oriented lattice bending of Co-CeO2 nanosheets for improving adsorption/activation properties of NO and O2. Co2-CeO2 catalyst displays the highest H2O-tolerance activity (T50 = 334 °C, TOF = 1.32 h−1) and excellent stability during soot oxidation in the presence of H2O. Combined with characterizations and DFT calculations, the mechanism was proposed: the active edge sites located at the oriented lattice bending of Co-CeO2 nanosheets can activate surface oxygen and gaseous O2, and active oxygen species can boost NO oxidation to NO2, which is a crucial step of NOx-assistant catalytic mechanism for soot oxidation. It provides a promising way for the rational design of high-performance non-noble metal catalysts for soot oxidation in practical applications.