Figure 4

(a) Appearance of typical xerogel sample and SEM images of xerogel samples with a varied amount of precursors added; (b) 1.22 g, (c) 1.34 g, (d) 1.46 g, (e) 1.58 g and (f) 1.70 g, respectively.

(a) Appearance of typical xerogel sample and SEM images of xerogel samples with a varied amount of precursors added; (b) 1.22 g, (c) 1.34 g, (d) 1.46 g, (e) 1.58 g and (f) 1.70 g, respectively.