Investigation of Formaldehyde Oxidation over Co3O4-CeO2 and Au/Co3O4-CeO2 Catalysts at Room Temperature: Effective Removal and Determination of Reaction Mechanism

Formaldehyde is regarded as the major indoor pollutant emitted from widely used building and decorative materials in airtight buildings, which should be eliminated under indoor environmental conditions. We report here catalytic oxidation process of formaldehyde over mesoporous Co3O4, Co3O4-CeO2, Au/Co3O4, and Au/Co3O4-CeO2 catalysts and their excellent catalytic performances at room temperature. These catalysts were prepared by a "nanocasting" method with the mesostructure generated from SBA-15 silica with 2D structure. The adsorbed surface species in the formaldehyde oxidation process are analyzed, and some key steps in the oxidation pathway, active sites, and intermediate species are proposed. Among the detected species, some kinds of formate species formed on the catalysts were indentified as intermediates, which further transformed into bicarbonate or carbonate and which decomposed to carbon dioxide. The role of the mesoporous Co3O4 and the gold nanoparticles in the mechanism are also revealed.