Robust ultrathin nanoporous MOF membrane with intra-crystalline defects for fast water transport

Abstract

Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues. Herein, a molecular-level intra-crystalline defect strategy combined with a selective layer thinning protocol is proposed to fabricate robust ultrathin missing-linker UiO-66 (ML-UiO-66) membrane to enable fast water permeation. Besides almost complete salt rejection, high and stable water flux is achieved even under long-term pervaporation operation in hash environments, which effectively addresses challenging stability issues. Then, detailed structural characterizations are employed to identify the type, chemical functionality, and density of intra-crystalline missing-linker defects. Moreover, molecular dynamics simulations shed light on the positive atomistic role of these defects, which are responsible for substantially enhancing structural hydrophilicity and enlarging pore window, consequently allowing ultra-fast water transport via a lower-energy-barrier pathway across three-dimensional sub-nanochannels during pervaporation. Unlike common unfavorable defect effects, the present positive intra-crystalline defect engineering concept at the molecular level is expected to pave a promising way toward not only rational design of next-generation MOF membranes with enhanced permeation performance, but additional water treatment applications.

Bimetallic electronic effects of Mn-doped Ni-MOF shuttle-like nanosheets remarkably enhance the supercapacitive performance

“…[14][15][16] They have aroused extensive attention in various fields such as gas storage, catalysis and so on. [17][18][19] Recently, MOFs have emerged directly as electrode materials in energy storage systems, which provide interesting attention for superior charge storage due to their high porosity and open metal center sites prone to reversible redox reactions. 20,21 However, MOFs, due to their weak coordination bonds, are easily hydrolyzed in the presence of water vapor, resulting in framework collapse.…”

Transport tuning strategies in MOF film synthesis – a perspective

“…[26][27][28][29] For example, more recent intracrystalline diffusion improvement strategies are achieved via hybridisation of ligands/metal nodes or controlled defect introduction into MOFs, both cases allowing for improved selective transport in the form of MOF membranes. 30,31 To fully utilise these various unique intracrystalline transport capabilities of MOFs on a more industrial scale for many different applications, a MOF lm may be required, which leads to the importance of the second medium of transport, the intercrystalline transport.…”

Superhydrophobic Carbon Nanotube Network Membranes for Membrane Distillation: High-Throughput Performance and Transport Mechanism

“…Water pollution and water resource scarcity are widely recognized as the foremost challenges of our time, affecting both the ecological environment and human health globally. − To combat these issues, membrane-based desalination technologies have been increasingly applied to purify unconventional sources such as seawater, brackish groundwater, and various wastewaters to augment fresh water supply. ,, Currently, membrane distillation (MD) has been proposed as a more promising technology than other conventional membrane-based processes such as reverse osmosis (RO) especially for challenging desalination applications such as hypersaline water treatment. − When using low-grade heat resources such as industrial waste/residual heat, solar energy, and joule heating, MD would be more highly practical considering its promising merits such as atmospheric pressure operation, excellent separation efficiency, ultra-high salinity enrichment (i.e., facile saturation and even crystallization), and feasible resource/energy extraction. , …”