One-Pot Template-Free Hydrothermal Synthesis of Monoclinic BiVO₄ Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

Figure 3

SEM images of BiVO₄ samples prepared with different amount of urea ranging from 0 (a), 3 (b), 6 (c) to 9 g (d) at 180°C for 24 h.

(a)

(b)

(c)

(d)