Overturned Loading of Inert CeO₂ to Active Co₃ O₄ for Unusually Improved Catalytic Activity in Fenton-Like Reactions

In the past decades, numerous efforts have been devoted to improving the catalytic activity of nanocomposites by either exposing more active sites or regulating the interaction between the support and nanoparticles while keeping the structure of the active sites unchanged. Here, we report the fabrication of a Co₃ O₄ -CeO₂ nanocomposite via overturning the loading direction, i.e., loading an inert CeO₂ support onto active Co₃ O₄ nanoparticles. The resultant catalyst exhibits unexpectedly higher activity and stability in peroxymonosulfate-based Fenton-like reactions than its analog prepared by the traditional impregnation method. Abundant oxygen vacancies (O_v with a Co⋅⋅⋅O_v ⋅⋅⋅Ce structure instead of Co⋅⋅⋅O_v ) are generated as new active sites to facilitate the cleavage of the peroxide bond to produce SO₄ ^.- and accelerate the rate-limiting step, i.e., the desorption of SO₄ ^.- , affording improved activity. This strategy is a new direction for boosting the catalytic activity of nanocomposite catalysts in various scenarios, including environmental remediation and energy applications.