Metal–Organic Frameworks Toward Electrocatalytic Applications

Abstract

Metal–organic frameworks (MOFs) are a class of porous materials constructed from metal-rich inorganic nodes and organic linkers. Because of their regular porosity in microporous or mesoporous scale and periodic intra-framework functionality, three-dimensional array of high-density and well-separated active sites can be built in various MOFs; such characteristics render MOFs attractive porous supports for a range of catalytic applications. Furthermore, the electrochemically addressable thin films of such MOF materials are reasonably considered as attractive candidates for electrocatalysis and relevant applications. Although it still constitutes an emerging subfield, the use of MOFs and relevant materials for electrocatalytic applications has attracted much attention in recent years. In this review, we aim to focus on the limitations and commonly seen issues for utilizing MOFs in electrocatalysis and the strategies to overcome these challenges. The research efforts on utilizing MOFs in a range of electrocatalytic applications are also highlighted.

Zirconium-Based Metal–Organic Framework Nanocomposites Containing Dimensionally Distinct Nanocarbons for Pseudocapacitors

“…Although most Zr-MOFs are electrical insulators, with the help of periodically aligned redox-active species appearing in the entire framework structure, charge transport can occur electrochemically via redox hopping in the presence of counterions. 25,26 The redox hopping in a variety of Zr-MOFs has been observed and widely investigated by researchers since 2013, 27−33 hopping and the active species for certain applications. However, it was found that in several cases the redox hopping in Zr-MOFs is not efficient enough and still limits the corresponding electrochemical performances.…”

Electrochemical Evolution of Pore-Confined Metallic Molybdenum in a Metal–Organic Framework (MOF) for All-MOF-Based Pseudocapacitors

“…We thus reasoned that a MOF thin film incorporated with spatially dispersed molybdenum-based active sites should be an attractive pseudocapacitive material that can maximize the density of accessible redox-active sites and thus the specific capacitance. However, the electrically insulating nature of most MOFs strongly limits their use in electrochemical applications. − For example, the Zr-MOF thin films installed with high-density and spatially dispersed molybdenum-based redox-active sites were found to show very limited electrochemical activity due to the sluggish charge transport between the redox-active sites . Recently, some published studies have used nickel- and cobalt-based MOFs in supercapacitors with KOH as the electrolytes. − To utilize water-stable MOFs in supercapacitors, strategies such as the design of electrically conductive MOFs − and the use of conductive MOF-based composites − have been proposed, but the examples are relatively rare.…”

Recent advances of electrochemical and optical enzyme-free glucose sensors operating at physiological conditions

“…To date, a large number of reports are available on the nonenzymatic detection of glucose based on nanostructured metals, alloys, metal-oxides, metal-sulfides, MOFs, and MAFs modified electrodes (Ansari et al, 2019;Lopa et al, 2019;Niu et al, 2016a;Kim et al, 2017;Rahman et al, 2010). However, most of these nanostructured-based sensors are not able to catalyze the oxidation of glucose under physiological pH conditions, rather they work efficiently in alkaline medium (George et al, 2018;Li et al, 2019a). Nanostructures based on Pt, Au and their alloys/composites showed high catalytic activity for oxidation of glucose at neutral pH.…”