Exploiting redox activity in metal–organic frameworks: concepts, trends and perspectives

Abstract

Of the many thousands of new metal-organic frameworks (MOFs) that are now discovered each year, many possess potential redox activity arising from the constituent metal ions and/or organic ligands, or the guest molecules located within their porous structures. Those redox states that can be accessed via postsynthetic redox modulation often possess distinct physical properties; if harnessed, these provide a basis for applications including microporous conductors, electrocatalysts, energy storage devices and electrochemical sensors, amongst others. This feature article highlights the latest developments in experimental, theoretical and computational concepts relevant to redox-active MOFs, including new solid state electrochemical and spectroelectrochemical techniques that have great utility in this field. A particular emphasis is on current and emerging trends at the fundamental level which underscore the importance of this promising class of electroactive materials for a wide range of technologically- and industrially-relevant applications.

Identifying promising metal–organic frameworks for heterogeneous catalysis via high‐throughput periodic density functional theory

“…An appropriate choice of where to artificially terminate the MOF unit cell is often not immediately obvious, and this approach is therefore not amenable to HT screening of MOFs with widely varying topologies. Finite cluster models also inherently introduce artificial boundary effects that have the potential to influence charge delocalization and pore‐based confinement effects . The use of periodic DFT to represent the full crystallographic unit cell naturally resolves these issues, and most implementations of periodic DFT are well‐suited for massively parallel calculations that can be used to treat the larger number of atoms in each simulation.…”

Intrinsically conducting metal–organic frameworks

“…Through-bond mechanisms take advantage of covalent bonding between appropriately matched metals and ligands; through-space mechanisms rely on noncovalent interactions. While not covered in this article, it is also important to note that post-synthesis modulation (such as via redox-state changes 10 or intercalation of guest molecules 9 ) has also been shown to modulate the conductivities of some MOFs.…”

Redox Active Metal– and Covalent Organic Frameworks for Energy Storage: Balancing Porosity and Electrical Conductivity

“…They have also been developed as anode material for batteries, as lithium or sodium storage within their pore structure or through conversion reactions by the destruction of the MOF structure . In addition, MOFs could be designed with redox‐active metal ions and/or ligands, which can be used to store electrochemical energy through redox reaction within the frameworks . There have been several reviews covering general applications of MOFs in energy storage .…”