Advancing osmotic power generation by covalent organic framework monolayer

Charged Nanochannels in Covalent Organic Framework Membranes Enabling Efficient Ion Exclusion

“…Covalent organic frameworks (COFs) are a burgeoning class of porous crystalline polymers with highly ordered, predesignable, and robust nanochannels assembled from molecular building blocks . The reticular chemistry based on a huge monomer library endows COF membranes with one-dimensional nanochannels that can be tailored at the atomic level to mimic biological ones and generate nanoconfined interactions with internal ions, which have achieved encouraging successes in boosting ion permeation for energy conversion and ionic separation. − In addition to ion permeation, ion exclusion is the other key function of membrane nanochannel and plays an essential role in clean water production by selective removing salts from water via pressure-driven filtration. , Benefited from the abundant uniform nanochannels, COF membranes are expected to realize fast water production . However, the nanochannel sizes of most COF materials fall in the range of ∼1–3 nm, which may allow for unobstructed permeation of small ions through COF membranes. − To elevate the ion exclusion ability of COF membranes, intensive efforts have been devoted to strengthening the steric hindrance for ion transport by narrowing nanochannels of COF membranes via physical shielding and chemical modification. − Such regulation on nanochannel size within the subnanometric range is challenging and may severely compromise water transport through COF membranes.…”

Nanoscale Pore–Pore Coupling Effect on Ion Transport through Ordered Porous Monolayers

“…(F) Summary of the salinity power harvesting performance of the COF monolayer membrane and other porous materials under the 0.5 M NaCl/0.01 M NaCl salt gradient. Reprinted with permission from ref . Copyright 2022 Springer Nature.…”

“…In a recent work, Yang et al reported a metaltetraphenylporphyrin-based COF monolayer membrane system (Figure 3C) with ordered nanopore array, being able to keep considerable membrane selectivity while ensuring the ultrahigh ionic conductivity. 44 Theoretical simulations disclosed that an obvious electrostatic pore−pore coupling effect occurred between adjacent charged nanopores with short enough interpore distance, which subsequently enhanced both the ion selectivity and conductivity of the COF monolayer membrane. On one hand, the charge of the nearest neighboring pore showed the positive effect on both the conductivity and the selectivity of the calculated central pore.…”

Gradient monolayered porous membrane for liquid manipulation: from fabrication to application

“… 105 Li's group demonstrated a covalent organic framework monolayer porous membrane for selective ion penetration, which could achieve an extremely low membrane resistivity and ultrahigh ion conductivity. 106 …”