Hydrogen-bonded organic frameworks (HOFs) have gained growing attention in the design and fabrication of advanced nanoporous membranes, while there have been few reports about their potential applications requiring long-term immersion of membranes in liquid, especially organic solvents. Herein, we fabricated solvent-resistant HOF@polymer (polyHOF) membranes through facile polymer network-reinforced synthesis strategy of polyHOF nanosheets, followed by vacuum filtration. Two hydrophilic polymers, polyvinyl alcohol (PVA) and polyethylene glycol (PEG), were selected to form multiple-site hydrogen bonding interactions with the pristine HOF framework. Benefiting from the reinforced hydrogen bonding networks and the electrostatic interactions between polymer chains and the HOF framework, these polyHOF membranes demonstrate exceptional stability in many solvents (even in water) for more than 30 days. Moreover, the enriched and regular channel of HOF enables the ultrafast solvent permeance (367.8 L·m⁻²·h⁻¹·bar⁻¹ to water) and precise molecular sieving (> 99.6% rejection to Evans blue). This modification technique presents a generic and promising strategy to robust HOF membranes, which can maintain high performance during long-term operation.

Hierarchical-structure materials hold great promise for numerous applied domains such as fuel cell, sensor, and optic. However, the developments are significantly impeded by the lack of efficient strategy permitting precise and efficient decoration of specific confined space. Here, an in-situ precise hybridization strategy is proposed to efficiently manipulate the nanostructure of membrane nanochannels. Typically, Nafion ionic nanochannels are impregnated with precursors via heat swelling, followed by microwave-assisted condensation to form polymer quantum dot network. The formation of polymer quantum dot network significantly improves the stability and functionality of ionic nanophase (i.e., ionic nanochannel). This helps hybrid membrane achieving enhanced proton conduction and methanol barrier properties, resulting in over ten times increase in proton/methanol selectivity. These then impart prominent device performances for both hydrogen and methanol fuel cells with the elevation of ~ 100%. Importantly, such function manipulation of ionic nanochannels is achieved with fully maintaining function of backbone nanophase. Besides, the regulation of physical topology and chemical environment of ionic nanochannel also brings optimization of gas and ion separation properties. This facile and versatile strategy may open up a new avenue for decorating confined space of many hierarchical-structure materials.

Porous laminar membranes hold great promise to realize ultrafast ion transfer if efficient and stable transfer channels are constructed in vertical direction. Here, metal-organic framework (MOF) nanosheets bearing imidazole molecules in the pores were designed as building blocks to assemble free-standing MOF laminar membrane. Then, Nafion chains were threaded into the pores induced by electrostatic attraction from imidazole molecules by slowly filtering dilute Nafion solution. We demonstrate that the threaded Nafion chains lock adjacent MOF nanosheets, affording highly enhanced structural stability to the resultant laminar membrane with almost no water swelling. Significantly, abundant acid-base pairs are formed in the pores along Nafion chains, working as efficient, continuous conduction pathways in vertical direction. Proton conductivities as high as 110 and 46 mS·cm^–1 are obtained by this membrane under 100% and 40% relative humidity (RH), respectively, which are two orders of magnitude higher than that of pristine MOF membrane. The conductivity under low humidity (40% RH) is even over 2 times higher than that of commercial Nafion membrane, generating the maximum power density of 1,100 mW·cm^–2 in hydrogen fuel cell (vs. 291 mW·cm^–2 of Nafion membrane). Besides, the influence of water state on proton transfer in confined space is investigated in detail.

Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries. Herein, a thin, laminar solid electrolyte is synthesized by filtrating –NH₂ functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide) chains induced by the hydrogen-bonding interaction from –NH₂ groups. It is demonstrated that the threaded poly(ethylene oxide) chains lock the adjacent metal-organic framework nanosheets, giving highly enhanced structural stability (Young’s modulus, 1.3 GPa) to 7.5-μm-thick laminar composite solid electrolyte. Importantly, these poly(ethylene oxide) chains with stretching structure serve as continuous conduction pathways along the chains in pores. It makes the non-conduction laminar metal-organic framework electrolyte highly conductive: 3.97 × 10⁻⁵ S cm⁻¹ at 25 ℃, which is even over 25 times higher than that of pure poly(ethylene oxide) electrolyte. The assembled lithium cell, thus, acquires superior cycling stability, initial discharge capacity (148 mAh g⁻¹ at 0.5 C and 60 ℃), and retention (94% after 150 cycles). Besides, the pore size of nanosheet is tailored (24.5–40.9 Å) to evaluate the mechanisms of chain conformation and ion transport in confined space. It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide) chains, and meanwhile inhibit their disorder degree. Specifically, the pore size of 33.8 Å shows optimized confinement effect with trans-poly(ethylene oxide) and cis-poly(ethylene oxide) conformation, which offers great significance in ion conduction. Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.