fig3

Figure 3. SEM images of as-prepared Cu(OH)₂ nanoneedles formed at 1.5 mA cm^-2 in a 2.0 mol L^-1 KOH solution at T = 28 ± 2 °C for different anodization times: (A) 300 s; (B) 500 s; (C) 1000 s; (D) 1500 s^[88]. Reproduced from Ref.^[88] with permission from the American Chemical Society.