LAUSR

Abstract Tuning the shape of tricobalt tetraoxide (Co 3 O 4 ) nanoparticles has been verified to significantly alter the redox feature and the catalytic property. This morphology-dependent nanocatalysis is frequently interpreted with respect to the preferential exposure of the reactive crystal facets that allowed a dense population of active sites for catalysis. In particular, the rod-shaped Co 3 O 4 nanoparticles, typically exposing a substantial fraction of the (110) facet, are featured by the coexistence of tetrahedral Co 2+ and octahedral Co 3+ sites that are intimately linked to the catalytic activity toward oxidation reactions. Continuous accumulation of experimental data over various Co 3 O 4 nanostructures has gradually clarified that identifying the active sites requires to consider the restructuring of the nanoparticles under the reaction conditions. Moreover, the synergistic effect between the reactive facet and its neighboring less-active facets could not be simply ruled out. Graphical abstract