RESUMEN
A novel method, thermo-catalytic decomposition of formaldehyde, is used to synthesize mesoporous ZnO crystals with enhanced photocatalytic activities. The mechanism of the mesoporous formation is investigated by synthesizing a series of samples at various systems and characterizing them with FT-IR, EDS, XRD, SEM, and TEM. The results show that formaldehyde can be adsorbed on the crystal planes of ZnO during the crystal growth and can then be catalytically decomposed into CO, CO2 and H2 during a sintering process. Because of the formation and the escape of these gases, which act as templates, the crystalline particles of ZnO are forced to rearrange consistently, and pores are formed in the internal crystal. Also, porous TiO2 crystals have been obtained via the same approach. Photocatalytic tests indicate that a porous ZnO crystal has higher activity than that of a nonporous one.
RESUMEN
Two kinds of ordered ZnO/TiO2 heterostructures were fabricated via a facile approach. The architecture of the TiO2 substrate could be controlled by alternating the filling forms of the template, and the morphology of the secondary ZnO nanostructure could be further tuned by adjusting the parameters of the hydrothermal reaction. Then two different morphologies of ZnO/TiO2 heteroarchitectures with ZnO nanorods and nanoplates growing on TiO2 shells and bowls were successfully achieved, respectively.