4. Conclusions
In conclusion, hierarchically porous structures assembling by
TiO2 nanoparticles with the diameter of 20nm were produced. In
this synthetic procedure, alginate template was used as sacrificial
template and dripped into a Ti(SO4)2 solution to initiate gelation
reaction. The porous architecture of the alginate templates were
successfully transferred to the TiO2 nanomaterials after freezing
drying and burning off the templates. The concentration of NaAlg
at a given Ti4+ concentration had a great influence on the
morphology of the final TiO2 materials. Generally, the volumes
of the pores increased gradually along with the increment of the
concentration of NaAlg solution, while the sizes of the TiO2
nanoparticles assembling into hierarchical structures had an
opposite trend. An investigation of the photocatalytic activity
shows that the hierarchically porous TiO2 nanomaterials are more
effective as a photocatalyst for RhB degradation under UV
illumination than the commercial available TiO2.