Figure 4
Surface morphologies of the nano-ZnO flakes after hydrothermal processing with different wzn2+ values: (a) 1 × 10−5 mol/L, (b) 2 × 10−5 mol/L, and (c) 10 × 10−5 mol/L (① uncovered substrate, ② bright white region, ③ yellowish gray region, and ④ grainy and pale yellow region).
