Three-dimensionally ordered macroporous Au/CeO2-Co3O4 catalysts with nanoporous walls for enhanced catalytic oxidation of formaldehyde

摘要

Three-dimensionally ordered macroporous (3DOM) Au/CeO2-Co3O4 catalysts were created via a precursor thermal decomposition-assisted colloidal crystal templating method. The 3DOM Au/CeO2-Co3O4 catalysts possessed well-defined 3DOM structures with adjustable pore sizes, and their compositions, phase structures, and surface elemental valence states can be well controlled by solely adjusting the Ce/Co molar ratio. Moreover, the nanoporous walls with pore sizes around ~3-4nm were created in 3DOM Au/CeO2-Co3O4 catalysts through the thermal decomposition of Co and Ce oxalate precursors during the preparation. The 3DOM Au/CeO2-Co3O4 catalysts exhibited superior catalytic activity for formaldehyde (HCHO) catalytic oxidation into CO2 and H2O with a 100% conversion rate at temperatures as low as ~39 °C. A catalytic mechanism of the synergistic effect between CeO2 and Co3O4 supports, which greatly accelerates the surface active oxygen migration and activates the Au species, was proposed for explaining the enhanced HCHO catalytic oxidation over 3DOM Au/CeO2-Co3O4 catalysts. The well-controlled method for creation of 3DOM Au/CeO2-Co3O4 catalysts with nanoporous walls could be adopted for generation of other catalytic materials with mixed macroporous and mesoporous structures. The superior catalytic activity of 3DOM Au/CeO2-Co3O4 catalysts makes them potentially applicable to indoor HCHO decontamination and industrial catalysis.