Oil–Water–Oil Triphase Synthesis of Ionic Covalent Organic Framework Nanosheets

Abstract

Ionic covalent organic framework nanosheets (iCOFNs) with long-range ordered and mono-dispersed ionic groups hold great potential in many advanced applications. Considering the inherent drawbacks of oil-water biphase method, herein, we explore an oil-water-oil triphase method based on phase engineering strategy for the bottom-up synthesis of iCOFNs.The middle water phase serves as aconfined reaction region, and the two oil phases are reservoirs for storing and supplying monomers to the water phase.Alarge aqueous space and lowm onomer concentration lead to the anisotropic gradual growth of iCOFNs into few-layer thickness,l arge lateral size, and high crystallinity.N otably,t he resulting three cationic and anionic iCOFNs exhibit ultra-high aspect ratios of up to 20,000. We further demonstrate their application potential by processing into ultrathin defect-free COF membranes for efficient biogas separation. Our triphase method may offer an alternative platform technology for the synthesis and innovative applications of iCOFNs.

Ultrathin Metal–Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity

“…2D MOF/COF nanosheets or membranes feature extremely interesting properties beyond their bulk counterparts such as ultrahigh surface area, highly exposed active sites for catalysis, sensing, or guest recognition, high electron mobility and conductivity, and unusual selectivity. − Recently, interfacial polymerization as a powerful methodology has been employed for the fabrication of crystalline, free-standing 2D metal- and covalent-organic framework nanosheets (MONs and CONs) or films . Conventionally, two active components (i.e., metal ion and organic linker for MONs or two organic linkers for CONs) are dissolved in two immiscible phases and only one type polymerization reaction occurs in the confined interface at room temperature (i.e., interfacial polycoordination or polycondensation for MONs or CONs, respectively; Figure a). ,− However, such a conventional interfacial protocol may not suitable for the preparation of 2D nanosheets of MOFs and COFs synthesized under solvothermal reaction conditions − from multiple components. It is envisioned that the competition among active components, the different reaction kinetics, the incompatibility (i.e., coordination reaction and organic condensation), and the interface interference during heating would hamper the formation of 2D nanosheets.…”

Missing‐linker Defects in Covalent Organic Framework Membranes for Efficient CO2 Separation

“…The amino‐functionalization COF nanosheets (denoted as NCOFN) were synthesized based on our previously reported oil‐water‐oil triphase method [15] . As schematically depicted in Figure 2a, 2,5‐dihydroxybenzaldehyde (Dhb) and 2,5‐dihydroxyterephthalaldehyde (Dha) at varied molar ratios (X=[Dhb]/[Dhb+Dha]×100) were dissolved in dichloromethane and placed in a glass beaker.…”

Covalent Organic Framework for Rechargeable Batteries: Mechanisms and Properties of Ionic Conduction

“…[69][70][71][72] Such rigid 1D nanochannels render COFs with great potentials as a novel conductor for efficient mass transfer. [23,[73][74][75] The transport of gas molecules, [76,77] liquid molecules, [78,79] protons, [80,81] and ions [31,43] in the nanochannels of COFs develop a novel research areas of mass transfer in nanoporous crystalline materials, and broadened the application regions, such as membrane separation, [82,83] proton exchange membrane fuel cells, [84,85] and solid-state batteries. [23] This review focuses on the ionic conduction behavior in the nanochannels of COFs and introduces its applications in rechargeable batteries.…”