In summary,ZnO hollow hierarchical microspheres with
different morphologies were successfully fabricated via a
simple trisodium citrate-assisted hydrothermal method.
According to the observations, a possible growth mechanism
of ZnO hollow hierarchical microspheres could be attributed to
alkali etching process and oriented assembly followed by an
Ostwald ripening process.Themorphologies of ZnO hollow
hierarchical microspheres could be controlled by a djustingthe
concentration of trisodium citrate, which played a crucial role
as abridging and suppress agent in the formation of ZnO
hollow hierarchical microspheres. Photocatalytic activity studies showed that themorphologies of ZnO photocatalyst had
certain effecton the photocatalytic performance. ZnO hollow
hierarchical microspheres with thin mutual crisscross nano-
sheets after3 h annealing at 300 1C exhibited the highest