Engineered Heterogenous Subnanochannel Membranes with a Tri‐Continuous Pore Structure of Large Geometry Gradient for Massively Enhanced Osmotic Power Conversion from Organic Solutions

Abstract

Heterogenous nanofluidic membranes with bi‐layer structures and ionic diode effect are shown great potential in efficiently harvesting the energy existing in a salinity gradient (or called the osmotic power conversion). However, exploitation of a heterogenous membrane with superior ion selectivity, excellent conductance, and strong ionic diode characteristics has remained a great challenge. Here, a novel heterogenous subnanochannel membrane with a tri‐continuous pore structure of a large geometry gradient ranging from sub‐nanoscale to nanoscale to sub‐microscale, which is composed of a thin and crack‐free layer of zeolitic imidazolate framework‐8 (ZIF‐8)/polystyrene sulfonate (PSS) membranes and an aligned branch‐type alumina nanochannel membrane (BANM) is reported. It is demonstrated that such a tri‐continuous pore structure can endow the exploited membrane, ZIF‐8/PSS@BANM, with enhanced ion selectivity, strong ion current rectification, and ultrafast ion transport properties, in organic electrolyte solutions. Thus, an amazingly high power of ≈50.5 W m−2 is produced by mixing a 2 m LiCl‐methanol and pure methanol solutions, which is over 45‐fold higher than the existing membranes. Realizing high ion selectivity and amplified directional ion transport at sub‐nanoconfined spaces in organic solvents paves the new way to develop ion‐channel‐mimetic membranes toward efficient ion separation and high‐performance energy harvesters for battery applications.

Harnessing Solar-Salinity Synergy with Porphyrin-Based Ionic Covalent-Organic-Framework Membranes for Enhanced Ionic Power Generation

“…Remarkably, the multifunctional membrane yielded a power density of up to 10.8 ± 0.5 W m –2 in the reverse electrodialysis (RED) mode at the mimic estuary conditions (0.5/0.01 M NaCl). When illuminated by a xenon lamp, this value surged to 18.0 ± 0.9 W m –2 , approximately quadrupling the standard commercial benchmark of 5 W m –2 . − This work represents one of the pioneering efforts in constructing ionic membranes with a photoelectronic effect. The versatility of COFs in developing multifunctional membranes underscores their immense potential for sustainable energy utilization and integration into next-generation devices.…”

Boosting Osmotic Energy Harvesting from Organic Solutions by Ultrathin Covalent Organic Framework Membranes

“…Besides, the recycling of electrode materials in power batteries also yield massive organic waste solution containing salts of lithium, cobalt, and manganese . Instead of sending to on-site incineration immediately, extracting osmotic energy from these waste organic solutions through reverse electrodialysis (RED) represents a promising approach to reuse such industrial wastes as valuable resources and mitigate the ever-growing energy needs. ,− In this context, numerous nanofluidic membranes have been constructed from polymers, nanofibers, nanosheets, metal–organic frameworks (MOFs), and their hybrids to enable the directed transport of counterions and harvesting osmotic energy from waste organic solutions. − However, compared to extracting osmotic energy from aqueous systems, − power harvesting from organic solutions can be much more complicated owing to the high viscosity of waste organic solutions and the diverse array of ion–solvent, ion–wall, and solvent–wall interactions within nanofluidic channels. Despite recent attention, this area has been scarcely explored. − In particular, existing membranes for harvesting osmotic energy from waste organic solutions have demonstrated limited output power density, primarily due to their high thickness reaching up to dozens of micrometers.…”

“…This improvement can be attributed to the suppressed ion concentration polarization and the increased ion diffusion rates resulting from the reduced solvent viscosities at a higher temperature. Compared with the current state-of-the-art results from reported porous membranes, − ,− the ultrathin ZnTPP-TPA membrane demonstrates an unprecedented output power density (Figure f and Table S4), primarily attributed to its minimal resistance to ion transport (Figure a, inset).…”

Pore-Forming Toxin-Driven Recovery of Peroxidase-Mimicking Activity in Biomass Channels for Label-Free Electrochemical Bacteria Sensing

“…Inspired by biological channel structures, artificial channels have attracted much research in recent years, showing potential in diverse fields including energy conversion, biosensing, enantiomer recognition, , and catalytic reaction monitoring. , These solid-state nanochannels/nanopores have tunable structure and stable mechanical and chemical properties. − Transmembrane ionic current recorded as current–potential ( I – V ) gives information on charged molecules/ions passing through the channels. Unfortunately, natural wood commonly possesses the poor sensitivity because of its macrosized pores and limited surface charges.…”