Post‐synthetic modifications in metal–organic frameworks for high proton conductivity

Abstract

A myriad of metal ions and organic linkers can be used to produce metal–organic frameworks (MOFs) with varied functionalities, porosities, and dimensionalities. Such diversity has garnered significant research interest, particularly in leveraging MOFs as proton conductors for fuel cells. One effective approach involves introducing guest molecules into MOF pores. These molecules serve either as proton carriers or as proton‐conducting media through potential hydrogen bonding networks. This review offers an organized overview of key methodologies historically employed to achieve superprotonic conductivity in MOFs. The article systematically categorizes these tactics into three primary groups: guest molecule encapsulation, modulation at metal‐coordination sites, and ligand functionalization. We succinctly discuss the roles of proton carriers, conducting media, and the overall MOF framework, emphasizing the significance of each strategy's application. In conclusion, we provide insights into the future development of MOFs as proton conductors, rooted in the categorization and conceptual understanding of these strategies.

A highly stable hydrogen-bonded organic framework for hydrogen storage

“…1,2 Similar to other porous crystalline materials, such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), HOFs exhibit numerous advantages, including high crystallinity, enduring porosity, adjustable functionality, and structural diversity, enabling their potential for various applications such as ionic conductivity, sensing, catalysis, and gas separation, similar to MOFs and COFs. 3–11 Thanks to the distinctive characteristics of the hydrogen bonds that form the meticulously organized framework, these materials exhibit unique properties rarely observed in other porous materials. One of these properties is the S-shape isotherm (type IV).…”

Ionic liquid-functionalized metal organic frameworks and their composite membranes for enhanced proton transport

“…Furthermore, post-synthetic modification methods applied to MOFs enhance effective proton transfer-related high proton conductivity, examples include guest molecule impregnation and direct oxidation/sulfonation. 44–48 Lately, the post-synthetic impregnation of ionic liquids (ILs) into the pores of MOFs has emerged as a promising strategy for enhancing proton conductivity. ILs have been highlighted as an effective liquid electrolyte at moderate temperatures due to their notable thermal stability, lack of volatility, non-flammability, and minimal corrosiveness.…”

Dual modifications of sensitizers and lanthanide ions on a two-dimensional zirconium-based metal–organic framework for photoluminescent detection

“…1,2 Furthermore, the use of organic sensitizers to render energy transfer to the adjacent lanthanide, also known as the “antenna effect”, can remarkably amplify the photoluminescent (PL) properties of lanthanide ions. 1,2 On the other hand, metal–organic frameworks (MOFs) are porous materials constructed from metal-ion clusters and organic linkers with high specific surface areas, interconnected pore structures and modulable chemical functionality, 3–8 which have been widely explored as active materials for a range of catalytic applications, 9–15 ionic conductors 16 and chemical sensors. 17–21 Spatially separated active sites immobilized within the highly porous scaffold are expected to be highly accessible to the reactants or analytes coming from the external environment, and the MOF in the form of solid is more easily recycled after use compared to those soluble luminescent materials.…”