Fig. 6: Polymer membrane-supported hierarchical nanochannel membranes.

Janus block copolymer membranes composed of two self-assembled membranes (a) and the corresponding power density evaluation (b). Reproduced with permission²⁵. Copyright 2017, American Chemical Society. Polyelectrolyte hydrogel-based heterogeneous membrane (c) and its power density evaluation (d). Reproduced with permission⁵⁴. CC BY (https://creativecommons.org/licenses/). I‒V curve of the Janus ionomer membrane in 3 M KCl (e) and power density evaluation under different salinity gradients (f). Reproduced with permission²⁶. CC BY 4.0 (https://creativecommons.org/licenses/by-nc/4.0/). Asymmetric sulfonated poly(ether ether ketone) membrane (g) and the corresponding power density evaluation (h). Reproduced with permission⁵⁵. CC BY (https://creativecommons.org/licenses/). Schematic of mushroom-shaped block copolymer nanochannel membrane (i) and its TEM image (j). The inset of (j) displays the density of mushroom-shaped nanochannels, which further reaches ~10¹² cm⁻². I‒V curve of the mushroom-shaped block copolymer nanochannel membrane under an extremely high salinity gradient (k) and output power densities (l). Reproduced with permission⁵⁷. CC BY 4.0 (https://creativecommons.org/licenses/by-nc/4.0/).