Metal–Organic Frameworks as Electrocatalysts

Abstract

Transition metal complexes are well‐known homogeneous electrocatalysts. In this regard, metal–organic frameworks (MOFs) can be considered as an ensemble of transition metal complexes ordered in a periodic arrangement. In addition, MOFs have several additional positive structural features that make them suitable for electrocatalysis, including large surface area, high porosity, and high content of accessible transition metal with exchangeable coordination positions. The present review describes the current state in the use of MOFs as electrocatalysts, both as host of electroactive guests and their direct electrocatalytic activity, particularly in the case of bimetallic MOFs. The field of MOF‐derived materials is purposely not covered, focusing on the direct use of MOFs or its composites as electrocatalysts. Special attention has been paid to present strategies to overcome their poor electrical conductivity and limited stability.

Mechanistic Elucidations of Highly Dispersed Metalloporphyrin Metal‐Organic Framework Catalysts for CO2Electroreduction

“…However, due to the high modularity in substrate identities and MOF precursor components, electrodes containing porphyrin‐based MOF structures can be highly variable, which can obfuscate the implications of MOF design strategies on reaction mechanism or transport properties [29] . Thus, experimental approaches focused toward elucidating the intrinsic CO 2 electroreduction mechanism for these materials are not well understood, which can obstruct clear design strategies for MOF electrocatalysts (both porphyrin‐based ones discussed here and other framework families [30] ), curtailing the advancement of MOF technologies for electroreduction applications.…”

Kinetic Impacts of Defect Sites in Metal–Organic Framework Catalysts under Varied Driving Forces

“…28 The porous nature of MOFs can improve the delivery of molecules or ions to electrode surfaces to circumvent the effects of mass transport limitations on catalysis-relevant current densities, 29 and the modularity of linker functional groups can promote inductive or second coordination sphere intermediate stabilization to overcome intermediate scaling relationships for multi-electron redox processes. 30 In these cases, the MOF acts as the active catalytic phase or as an auxiliary component that can utilize specific material properties (e.g., porosity or functional group proximity) to facilitate catalysis. 31 Conversely, MOFs can act as scaffolds that reconstruct under potential bias (or external extreme thermal bias), resulting in MOF-derived metal or metal composite materials (e.g., oxides, phosphides, sulfides, etc.)…”

“…The aforementioned material properties of MOFs also confer a wide range of design approaches that can lead to their development as active and stable electrocatalysts, including alternatives to bulk noble metal electrocatalysts that are among the most active materials but are too costly for practical applications for reactions such as carbon dioxide reduction (CO 2 R), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR) . The porous nature of MOFs can improve the delivery of molecules or ions to electrode surfaces to circumvent the effects of mass transport limitations on catalysis-relevant current densities, and the modularity of linker functional groups can promote inductive or second coordination sphere intermediate stabilization to overcome intermediate scaling relationships for multi-electron redox processes . In these cases, the MOF acts as the active catalytic phase or as an auxiliary component that can utilize specific material properties (e.g., porosity or functional group proximity) to facilitate catalysis .…”

Yttrium-doped cobalt-based metal–organic frameworks for selective electrooxidation of glycerol coupled with hydrogen production

“…16,17 Metal-organic frameworks (MOFs) are considered to be a promising catalytic application platform. 18 For one thing, MOFs have abundant catalytic molecular units similar to metal complexes. For another, MOFs can be used as a heterogeneous catalyst and can be well recycled after catalytic operation.…”