Figure 12.

(a) Schematic illustration of creating surface roughness by chemical etching of an Al plate with an acidic solution of HCl, isopropanol and DI water; (b–f) the SEM images of hierarchical structures on an Al surface after modification in (b) HCl solution (Reprinted from [67] with permission from Elsevier); (c,d) FeCl₃ solution (Reprinted with permission from [66]. Copyright {2021} American Chemical Society); and (e,f) ammonia solution (Reprinted from [68] with permission from Elsevier).