Hollow-Structural Ag/Co3O4 Nanocatalyst for CO Oxidation: Interfacial Synergistic Effect

Porous hollow-structural Co3O4 micropolyhedra were prepared by direct pyrolysis of zeolitic imidazolate framework (ZIF)-67 crystals in air. The Co3O4 primary nanoparticles and pore diameters increase with increasing calcination temperatures. Compared with the single Co3O4-350 catalyst, CO oxidation activity is greatly enhanced over the interface Ag/Co3O4-350 catalyst (T100 = 120 °C and 8.8 × 10–2 molCO nm–2 s–1), which can be attributed to the improvement in surface-active oxygen and their mobility at the interface between Ag and Co3O4. The DRIFTS results proposed the CO oxidation reaction mechanism over the Ag/Co3O4 interface catalyst, and the formed Ag compound with surface oxygen species is more active for CO oxidation. The interface between Ag and Co3O4 facilitates both the oxygen activation and CO adsorption, hence lowering the reaction energy barrier and boosting the CO oxidation performance.