Synthesis of Monodisperse Walnut-Like SnO₂ Spheres and Their Photocatalytic Performances

Figure 2

SEM images of the samples obtained with various KOH concentrations for 15 h: (a) 2 M, (b) 3 M, (c) 4 M, and (d) 4 M at high magnification.

(a)

(b)

(c)

(d)