“…On the one hand, they own the advantages of enhanced light absorption, as a result of multireflection within the numerous voids of the materials, thus usually exhibiting higher photo efficiency. − On the other hand, the assembled nanostructures provide much more exposed surface region, well facilitating the adsorption and photoreaction of reactants. Till now, many inorganic photocatalytic materials are able to be prepared in flower like hierarchical structures, such as Bi 2 WO 6 , Bi 2 MoO 6 , ZnO, ,, CeO 2 , and BiOX (X = Cl, Br, I). , …”