Enhancement of carbon monoxide catalytic oxidation performance by co-doping silver and cerium in three-dimensionally ordered macroporous Co-based catalyst

Abstract

Carbon monoxide (CO) catalytic oxidation offers an effective solution for environmental pollutant; however, its progress is limited by sluggish kinetics, and efficient catalysts remain scarce. Herein, we prepared Ag-Ce co-doped three-dimensionally ordered macroporous (3DOM) Co-based catalysts through the synergistic approach of co-doping and morphology control, systematically investigating their CO catalytic oxidation mechanisms. The appropriate amount of Ag-Ce co-doping maintained the original 3DOM structure, promote the mass transfer and diffusion of CO, promoted the redox capacity by increasing the ratio of Co³⁺ to surface reactive oxygen species (O⁻/ O^2–), achieving low temperature conversion of CO. Specifically, concentration of Co³⁺ is promoted via Co²⁺ + Ag⁺ → Ag⁰ + Co³⁺ and then combining the generated the active oxygen specie reduce the CO conversion temperature (Co³⁺ + O⁻/ O^2– + CO → CO₂ + Co²⁺). Among them 3D-5 %AgCo₁₆Ce₁ exhibited a lower activation energy (E_a) and T₅₀, which were only 48.79 KJ mol⁻¹ and 76.8 °C, respectively. Theoretical calculation indicated that the synergistic of co-doped system can lower down the O₂ dissociation energy barrier by 0.242 eV compared with 3D-Co₁₆Ce₁, thus facilizing the generation of active oxygen species and improving the oxidation kinetic of CO. This work innovated the preparation method of 3DOM co-doped system and provided opportunities to design high-performance heterogeneous catalysts.