Development of Surfactant-Templated Mesoporous CeO₂ with Enhanced CO Oxidation Activity: Comparative Optimization by Response Surface Methodology Using Different Surfactants

Mesoporous cerium dioxide (CeO₂) has attracted considerable attention for oxidation catalysis due to its reversible Ce⁴⁺/Ce³⁺ redox couple and oxygen storage capability. However, the catalytic performance of CeO₂ strongly depends on synthesis conditions that govern mesostructure development and defect formation. In this study, surfactant-templated mesoporous CeO₂ was synthesized using cetyltrimethylammonium bromide (CTAB) and Pluronic F127 as structure-directing agents. Response surface methodology (RSM) based on a Box–Behnken design was employed to systematically evaluate the effects of pH, metal-to-surfactant ratio, and hydrothermal temperature on textural properties and CO oxidation activity. Statistically validated models revealed distinct parameter sensitivities for CTAB- and F127-templated systems. Optimized catalysts exhibited significantly enhanced catalytic performance compared with suboptimal and commercial CeO₂, achieving markedly lower light-off temperatures. Structural characterization demonstrated that optimization promoted smaller crystallite size, well-developed mesoporosity, and increased Ce³⁺ fraction accompanied by enriched oxygen vacancies and surface-active oxygen species. H₂-TPR analysis further confirmed improved reducibility and enhanced oxygen mobility in optimized samples. The superior CO oxidation activity was attributed to defect-engineered surfaces facilitating oxygen activation via a Mars–van Krevelen mechanism. This work establishes a quantitative synthesis–structure–redox–activity relationship and demonstrates that statistical optimization combined with surfactant-templated design is an effective strategy for engineering high-performance mesoporous CeO₂ catalysts.