Fig. 1 presents the FT-IR spectra of the as-synthesized and calcined
samples of the TiO2–SiO2 aerogel with the Si-to-Ti ratio of
2.3 synthesized via this process. The peaks assignable to symmetrical
and asymmetrical stretching of Si–O–Si can be seen at 780–
815 cm1 and 1080–1090 cm1 respectively. The existence of the
hetero-linkage Ti–O–Si bond at 935–950 cm1 indicates the incorporation
of TiO2 into SiO2 to form binary TiO2–SiO2 systems
[1,11,27,32]. The broad absorption peaks at 3430–3440 cm1 and
1625–1635 cm1 correspond to the hydroxyl groups (–OH) as a result
of physically adsorbed water by the aerogel composites [25].
Additionally, the as-synthesized samples and those calcined at
temperatures up to 500 C displayed peaks at 850–860 cm1 and
1255–1260 cm1 assignable to the absorption by Si–CH3 groups
signifying the interaction of silica with terminal –CH3 groups as a
result of modification [19,20,33]. These hydrolytically stable
groups were formed as a result of replacement of –OH groups during
surface modification of the alcogel