Lamellar membranes with two-dimensional nanofluidic channels hold great promise in harvesting osmotic energy from salinity gradients. However, the power density is often limited by the high transmembrane resistance primarily caused...

No abstract

The idea of spatial confinement has gained widespread interest in myriad applications. Especially, the confined short hydrogen-bond (SHB) network could afford an attractive opportunity to enable proton transfer in a nearly barrierless manner, but its practical implementation has been challenging. Herein, we report a SHB network confined on the surface of ionic covalent organic framework (COF) membranes decorated by densely and uniformly distributed hydrophilic ligands. Combined experimental and theoretical evidences have pointed to the confinement of water molecules allocated to each ligand, achieving the local enrichment of hydronium ions and the concomitant formation of SHBs in water-hydronium domains. These overlapped water-hydronium domains create an interconnected SHB network, which yields an unprecedented ultrahigh proton conductivity of 1389 mS cm−1 at 90 °C, 100% relative humidity.

Graphene oxide (GO) membrane, bearing well-aligned interlayer nanochannels and well-defined physicochemical properties, promises fast proton transport. However, the deficiency of proton donor groups on the basal plane of GO and weak interlamellar interactions between the adjacent nanosheets often cause low proton conduction capability and poor water stability. Herein, we incorporate sulfonated graphene quantum dots (SGQD) into  GO membrane to solve the above dilemma via synergistically controlling the edge electrostatic interaction and in-plane π–π interaction of SGQD with GO nanosheets. SGQD with three different kinds of electron-withdrawing groups are employed to modulate the edge electrostatic interactions and improve the water swelling resistant property of GO membranes. Meanwhile, SGQD with abundant proton donor groups assemble on the sp2 domain of GO via in-plane π–π interaction and confer the GO membranes with low-energy-barrier proton transport channels. As a result, the GO membrane achieves an enhanced proton conductivity of 324 mS cm–1, maximum power density of 161.6 mW cm–2, and superior water stability when immersed into water for one month. This study demonstrates a strategy for independent manipulation of conductive function and nonconductive function to fabricate high-performance proton exchange membranes.