Pore engineering in covalent organic framework membrane for gas separation

Pore-in-Pore Engineering in a Covalent Organic Framework Membrane for Gas Separation

“…The H 2 /CH 4 separation selectivities of the LA-α-CD-in-TBPa-1 membrane, LA-α-CD-in-TBBD membrane, and LA-α-CD-in-TpBD membrane could reach 30.6, 20.6, and 21.5, respectively. Moreover, their comprehensive performances are also competitive and higher than most of the existing COF gas membranes without α-CDs, 29,30 illustrating the potential and broad applicability of this pore-in-pore strategy. Molecular Dynamics Simulation and Transport Mechanism Analysis.…”

“…Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers connected by organic building units through covalent bonds into highly ordered and periodic network structures. − These materials have gained tremendous attention because of their potential applications in diverse fields such as gas adsorption for separation and storage, catalysis, energy storage, optoelectronics, and many more. − Given by the versatile architectures, tunable functionalities, and well-organized pore system as well as good thermal and chemical stability, the COFs, especially the Schiff base-related 2D COF family, hold great potential for energy-efficient membrane-based molecular/ion separations in the chemical industry. − For this purpose, the development of COF membranes has attracted extensive interest in the last five years and is booming right now. − A variety of self-supporting or supported high-quality COF membranes were developed with a fascinating performance in liquid-phase separation processes such as desalination, , dye wastewater purification, − and organic solvent nanofiltration. − However, progress on COF-based membranes in selective gas separation is lagging, mainly due to the intrinsic nanometer-sized pores of the COF family (typically 0.6–10 nm) which are much larger than the kinetic diameter of ordinary gas molecules (0.25–0.5 nm). − Based on the topology diagrams and pore-wall surface engineering, − it is difficult to design the COFs with an aperture size in the gas molecular-selective region. Approaches including staggered stacking, − oriented growth, and hybridization with other microporous nanomaterials , have been explored to reduce the effective pore size of COF membranes toward the ultramicroporous range, mainly aiming at improving the molecular sieving mechanism.…”

On-Surface Synthesis and Applications of 2D Covalent Organic Framework Nanosheets

“…Due to their ultra-high porosity, low mass density, rich chemical/physical properties, and high structure tunability at the atomic level, 2D COF films have shown potential applications in various emerging fields [49,50], such as field effect transistors (FETs) [51,52], light-emitting diodes (LEDs) [53,54], gas separation [14,15,55], energy storage [56], and sensors [57]. A few cutting-edge applications of 2D COFs are illustrated in Figure 7.…”

“…Due to their fascinating properties, including thermal stability and rich chemical/physical properties, COFs have shown potential applications in many emerging fields, such as catalysts [5], sensors [6,7], gas separation [8,9], and energy storage [10,11]. Furthermore, the pore size of COFs can also be artificially regulated to achieve the specific properties, which can broaden the scope of their application [12][13][14].…”