Systematic shape evolution of Co3O4nanocrystals from octahedra to spheres under the influence of C2O42−and PVP

A series of Co3O4 nanocrystals with systematic shape evolution from octahedra to corner-truncated octahedra, corner-truncated cubes, globate polyhedra and micro-spheres were successfully synthesized under the influence of C2O42− and PVP. It was proved that crystal facet growth limitation caused by the adsorption of C2O42− and PVP on the surface of Co3O4 particles played a crucial role in this shape evolution process. Besides obtaining a series of intermediate Co3O4 nanocrystals exposing different facets, this strategy could also show the relationship between these structures. The present work extends the PVP-assisted method to realize the shape evolution process of metal oxide nanomaterials.