Facet effect on nanosheet Co₃O₄ catalysts for toluene oxidation: Decisive role of Co³⁺ and reaction-induced oxygen vacancy

Co₃O₄ is recognized as an advantageous material for harmful VOC abatement. In this paper, three types of Co₃O₄ catalysts exhibiting either nanosheet morphology or nanosheet tissue structure were synthesized and applied in the combustion of toluene. The characterization results highlight the significance of Co³⁺ species over surface oxygen. Moreover, the oxygen vacancies of the catalyst formed during the reaction process were found to play a more critical role in influencing the catalytic performance than the oxygen vacancies present in the original catalyst. Through this study, we gained valuable insights into the facets, Co³⁺ species, and oxygen vacancies, which hold promising potential for enhancing the development of Co₃O₄ catalytic material for practical applications in toluene degradation.