fig4

Figure 4. (A, B) Magnified SEM images of micro-nano structures fabricated by fs laser on Cu surfaces. This figure is quoted with permission from Fan et al.^[116] Copyright 2016 Royal Society of Chemistry. (C) A schematic drawing of hierarchical structured evaporators providing a synergistic performance in light absorption and trapping. This figure is quoted with permission from Lei et al.^[114] Copyright 2021 Springer Nature (D, E) SEM images of the hierarchical-Graphene foam. This figure is quoted with permission from Ren et al.^[115] Copyright 2017 Wiley-VCH (F, G) Comparison of a flat surface to a hierarchical structure in terms of their light reflection and dependence on the incident light angle. This figure is quoted with permission from Wang Peng^[8]. Copyright 2018 Royal Society of Chemistry.