shows the TEM images of TiO2 and 20% FTC. The synthesized
TiO2 nanoparticles (NPs) (Fig. 3A) uniformly disperse and display
spherical morphology with an average diameter of 15 nm. The 20%
FTC (Fig. 3B) contains both spherical NPs and rod NPs with an average
diameter of 20 nm and length of 100 nm. We also observed the decoration
of spherical NPs onto the surface of rod NPs, suggesting that
FeTiO3 tends to form rod NPs and from which TiO2 NPs grew on.
Fig. 3c shows the HR-TEM image of 20% FTC, presenting the lattice
fringe of TiO2 and FeTiO3 as well as the surface-phase junction in
FTC. Our observation suggests that FeTiO3/TiO2 heterojunction photocatalyst
has been formed. Gao et al. was pioneering in synthesizing
FTC using hydrothermal method [24]. They used commercially available
micrometer-sized FeTiO3 precursor which might limit the contacting
area between the two phases and degrade the homogeneity.
On contrast, the FTC synthesized by the hydrothermal route in this
study is more homogeneous and capable of providing more active
sites for catalytic reaction.