821204.fig.004a
(a)
821204.fig.004b
(b)
821204.fig.004c
(c)
Figure 4: SEM images of N-TiO2 samples prepared from precursors with different N : Ti molar ratios, fired at 250°C, 3 h, and 500°C 1 min. Ramp: 10°C/min. (a) N : Ti, 0 (TiO2); (b) N : TI, 4 : 1; (c) N : Ti, 8 : 1.