Zhirong Yang

Achieving high proton conduction in proton exchange membranes (PEMs) at low relative humidity (RH) remains challenging due to the suppression of the Grotthuss mechanism. Engineering microphase separation with aligned hopping sites is an effective strategy to drive the mechanism shift, yet simultaneously maintaining membrane durability remains difficult. Here, we propose a hierarchical self‐assembly strategy that precisely introduces guest hopping sites into the microphase‐separated region without damaging the membrane's durability. By regulating the polyimide (PI) doping level in sulfonated polyetheretherketone (SPEEK) membranes, an optimal balance of proton conduction and stability is achieved at a bridged ─N─…SO ₃ H─ acid–base pair ratio of 13%. Precise hybridization of acid–base hydrogen‐bonded organic frameworks (ABHOFs) into microphase‐separated regions constructs guest acid–base pair sites and promotes the ordered arrangement of host sites. Spatial alignment of guest‐host hopping sites creates long‐range and low‐resistance channels. Both site and energy matching enable a transition from vehicle‐mediated to Grotthuss mechanisms under low RH. The resulting SP/PI@ABHOF membranes exhibit high proton conductivities of 193.6/50.8 mS cm ^{− 1} at 80°C under 100%/20% RH, with peak power densities reaching 1221.2/419.6 mW cm ^{− 2} . Significant enhancements in mechanical strength, cyclic stability, and hydrogen‐permeation current density were also achieved, surpassing the performance of benchmark PEMs, including Nafion 212 and GORE membranes.

Mobil‐type five (MFI) zeolite membranes are predominantly employed for the exceptional separation of PX from xylene isomers (p‐, m‐, o‐xylene, PX, OX, MX). However, the defect‐free fabrication complexity and the limited mechanical flexibility hinder the full exploitation of the size‐sieving effect. Here, an approach is proposed involving the alternating intercalation of negatively charged covalent organic frameworks (COF) nanosheets into positively charged MFI layers to mitigate the adverse effects of MFI defects. The alternating charge pairs facilitate the rapid and selective transport of PX, resulting in high separation factors of 29 for PX/OX(1:1) and 24 for PX/MX(1:1) with a PX permeance of 1.46 × 10⁻⁷ mol m⁻²s⁻¹ Pa⁻¹ through organic solvent nanofiltration, and 586 for PX/OX and 566 for PX/MX with a PX permeance of 0.87 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ through pervaporation. Molecular dynamics simulation shows that the altered charge pairs enhance sensitivity to subtle differences in xylene polarity: π‐bond electrostatic field shifts of COF induce repulsion of OX and MX relative to PX from crossing MFI defects. The introduction of COF layer reduces the brittleness of MFI membrane, contributing to >2‐fold increase in mechanical stability and durability. This study provides a promising strategy for the efficient separation of xylene isomers and other isomers.