Co3O4 nanocrystals and Co3O4–MOx binary oxides for CO, CH4 and VOC oxidation at low temperatures: a review

Among the possible substitutes for noble metals, cobalt-based catalysts represent promising alternative systems. In recent years, many articles have been devoted to the synthesis, characterization and reactivity of cobalt oxides. This article provides a comprehensive review of the state-of-the-art activities that concentrate on the synthesis, structural properties and catalytic applications of Co3O4 nanocrystals and Co3O4–MOx binary oxides in CO, CH4 and VOC oxidation at low temperatures. It begins with the major synthetic approaches and basic properties of Co3O4 nanocrystals and Co3O4–MOx binary oxides and subsequently highlights the relationship between the peculiar structure of Co3O4 nanocrystals and their catalytic activity (or between the redox properties of Co3O4–MOx binary oxides and their catalytic activity). Finally, the active sites and key factors determining the catalytic oxidation over Co3O4 and Co3O4–MOx are discussed. The perspective with respect to future research on Co3O4 nanocrystals and Co3O4–MOx binary oxides is considered.