Mesoporous Co₃O₄ Nanoparticles with Enriched Oxygen Defects for Efficient NO Oxidation

Catalytic conversion of NO to NO2 stands as a pivotal step governing NOx purification technology, with its effectiveness relying heavily on the utilization of high-performance catalysts. Herein, we harness a facile ligand-assisted self-assembly strategy to fabricate mesoporous Co3O4 with abundant oxygen vacancies (M-Co3O4), aiming at improving the activity of NO oxidation. For comparison, Co3O4 nanoflakes (F-Co3O4) and bulk Co3O4 (B-Co3O4) were synthesized from a hydrothermal method and direct calcination of cobalt nitrate, respectively. Activity results reveal that M-Co3O4 can oxidize 88% of NO at 275 °C under a GHSV of 180,000 h–1, surpassing both F-Co3O4 (70% at 325 °C) and B-Co3O4 (66% at 325 °C). Extensive characterizations indicate that the exceptional activities of M-Co3O4 are predominantly attributed to the synergistic effects of its surface Co2+ species, weak Co–O bond strength, and high mobility of surface lattice oxygen. This work lays the groundwork for the advancement of high-performance Co3O4-based catalysts for atmospheric contaminants remediation.