Homogeneous CoCeOx nanocomposites with rich oxygen vacancies for effective catalytic oxidation of toluene

[Display omitted] •The carbon spheres facilitate the dispersion of CoCe species, leading to homogeneous untrafine nanocomposites.•Small crystal size, larger pore size and abundant oxygen vacancies account for the superior performance of the catalyst.•The intermediates and reaction pathway of toluene oxidation are investigated over the CoCe oxide catalyst. A CoCeOx nanocomposite catalyst was obtained by a template sacrificing method, with hydrothermally prepared carbon spheres as the template. The existence of plenty of functional groups on the surface of carbon spheres led to the uniform dispersion of the Co and Ce metal oxides, with an average crystal size of 6.1 nm. Compared with the conventional coprecipitation method, the catalyst prepared by template sacrificing exhibits better catalytic activity and stability, lower activation energy, and higher turnover frequency in the catalytic oxidation of toluene. The small crystal size, larger pore size, enhanced low-temperature reducibility and abundant oxygen vacancies are responsible for the superior activity. Using in situ FTIR, the oxidation intermediates and reaction pathways were proposed over the Co-Ce oxide nanocomposite catalyst. This work provides an effective method for the synthesis of uniform bimetallic nanocomposites with ultrasmall crystal size, which opens an avenue for new catalyst design methods for the oxidation of volatile organic compounds.