Microwave-Assisted Rapid Synthesis of Nanoscale MOF-303 for Hydrogel Composites with Superior Proton Conduction at Ambient-Humidity Conditions

Abstract

Metal–organic frameworks (MOFs) have attracted extensive attention in the field of proton conduction and show great promise to be ideal alternative solid proton conductors. However, most of the MOF proton conductors are limited to operating at high-humidity conditions because their proton conduction is highly dependent on water molecules that act as proton-transfer media. Herein, we demonstrate the rapid and high-yield preparation of MOF-303 nanocrystals with controllable sizes from 500 to 50 nm through a microwave-assisted synthetic method. The nanocrystals doped with methanesulfonic acid (MeSA), MeSA@MOF-303, display high proton conductivity (σ) up to 10–2 S cm–1 at 98% relative humidity (RH). Most importantly, the MeSA@MOF-303-PVA hydrogels comprised of MeSA@MOF-303 nanocrystals with poly­(vinyl alcohol) (PVA) are prominent proton-conducting materials with σ > 10–3 S cm–1 at ambient-humidity conditions. This study demonstrates an efficient approach for improving the water-retention capacity of porous proton conductors to further realize high proton conductivity at ambient and even lower humidity conditions.

In Situ Growth of MOF-303 Membranes onto Porous Anodic Aluminum Oxide Substrates for Harvesting Salinity-Gradient Energy

“…Figure a shows the XRD patterns of the composite membranes, indicating obvious differences in the structure. The XRD peaks of the T1 composite membrane match well with those of the simulated MOF-303 structure, and the morphology of closely packed and uniformly arranged cubic particles is observed in Figure b, which is consistent with the results of previous studies. , As can be observed in Figures a and S5b, the XRD patterns on both sides of T2–T5 differ significantly from T1 in the number and position of the characteristic peaks. This difference in the XRD pattern is more likely to be the presence of a new material with a specific crystal structure in the sample rather than a difference due to a shift in peak position.…”

Mechanochemical Synthesis of MOF-303 and Its CO2 Adsorption at Ambient Conditions

“…Note that this adsorption capacity value exceeds the best values obtained for ultramicroporous carbons, which have been considered highly effective adsorbents for CO 2 capture at ambient conditions [ 51 ]. As far as the authors know, the SSA of MOF-303 ranges from about 600 m 2 /g [ 52 ] to even 1529 m 2 /g [ 22 ], depending on the synthesis method, including the purification step [ 12 , 52 ].…”

Controllable Synthesis and Ultrahigh Anisotropic Single-Crystal Proton Conduction of a Hydrogen-Bonded Organic Framework

“…In the past decades, the crystalline porous materials of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) which are built up from coordinated and covalent bonds, have been popularly explored in the field of proton conduction owing to their tunable structures and functional channels. − In contrast to MOFs and COFs, hydrogen-bonded organic frameworks (HOFs) are highly porous and inherently present well-defined intermolecular noncovalent hydrogen-bonding interactions, − more favorable for the proton transfer, making them versatile platforms as outstanding solid-state proton conduction materials. − Another notable characteristic of HOFs is their typically simplistic structural components. This simplicity enables a precise analysis of the relationship between structure and properties, specifically based on single-crystal proton conduction.…”