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.