Flower power: Unique 3D flower-like Bi2O3 hierarchical nanostructures were synthesized using a mild aqueous template-free method (see figure). By introducing VO3− into the reaction system, which mediated the nucleation and growth of Bi2O3, the in situ self-assembly of 3D hierarchitectures from 2D nanosheets has been realized.
By introducing VO3− into the reaction system, uniform hierarchical nanostructures of Bi2O3 have been successfully synthesized by a template-free aqueous method at 60–80 °C for 6 h. The as-prepared hierarchitectures are composed of 2D nanosheets, which intercross with each other. Based on the electron microscope observations, the growth of such hierarchitectures has been proposed as an Ostwald ripening process followed by self-assembly. The nucleation, growth, and self-assembly of Bi2O3 nanosheets could be readily tuned, which brought different morphologies and microstructures to the final products. Pore-size distribution analysis revealed that both mesopores and macropores existed in the product. UV-vis spectroscopy was employed to estimate the band gap energies of the hierarchical nanostructures. The photocatalytic activities of as-prepared Bi2O3 hierarchitectures were 6–10 times higher than that of the commercial sample, which was evaluated by the degradation of RhB dye under visible light irradiation (λ>420 nm).