Catalytic soot oxidation using hierarchical cobalt oxide microspheres with various nanostructures: Insights into relationships of morphology, property and reactivity

•Hierarchical Co3O4 Microspheres (HCOMs) with Various Nanostructures are fabricated.•Catalytic properties of four HCOMs are greatly influenced by their morphologies.•Co3O4 with pyramid structures (COP) is the most advantageous HCOM for soot oxidation.•These HCOMs could be also recyclable for soot oxidation over multiple cycles.•The relationship between morphologies, properties and catalytic activities can be correlated.