Preparation of spinous ZrO2 microspheres with tunable shell and chamber structure by controlling pollen as a...

Spinous hollow and core-shell microspheres constructed from ZrO2 nanoparticles and keeping the complex morphology of pollens were prepared by bio-template route. Compared with other bio-templates synthesis, the superiority of our synthesis is that the growth of nanoparticles can be controlled in particular space of template. The theory of pollen as a reactor and a possible formation mechanism were proposed which could explain the tunable structure: under a mild condition, the pollen wall will be controlled as a nanoparticles bio-reactor to form the hollow structure; when under a strenuous condition, pollen wall and pollen interior will act as a whole bio-reactor, and the core-shell structure could be obtained. At the same time, the shell thickness can be controlled through etching pollen wall by different concentrations HCl. These microspheres can be used as photocatalyst due to their unique structure. This work provides a novel pathway to the synthesis of hollow nanostructure spheres with complicated structure and morphology.