382043.fig.002a
(a) Silica
382043.fig.002b
(b) Titania
382043.fig.002c
(c) Silica
382043.fig.002d
(d) Titania
Figure 2: SEM images of mesoporous silica (a) and (c) and titania (b) and (d) rods on the silicon substrate: Figures (a) and (b) are top-surface images, while Figures (c) and (d) are cross-sectional images.