Two‐Dimensional Metal–Organic Frameworks and Covalent–Organic Frameworks for Electrocatalysis: Distinct Merits by the Reduced Dimension

Abstract

The demand to develop highly efficient electrocatalysts for renewable energy conversion has dramatically increased over the past few years. Metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs) have emerged as promising materials to improve the catalytic efficiency of a variety of electrochemical energy conversion reactions. Compared to 3D bulk MOFs and COFs, which are commonly obtained by typical synthesis routes, 2D MOFs and COFs are achieved through innovative synthesis strategies, and exhibit further benefits in terms of chemical and structural properties. Specifically, the large porosity and ultrathin structure of the 2D materials contribute to exotic properties such as large surface area, mechanical flexibility, enhanced electrical conductivity, and rapid mass transport during reactions, which are highly applicable to electrocatalysis. In this review, the synthesis methods of 2D MOFs and COFs are first discussed. Then, the distinct advantages and recent advances in 2D materials for electrocatalytic reactions, including water splitting, O2 reduction reaction, CO2 reduction reaction, and N2 reduction reaction, are introduced. Finally, based on existing challenges, crucial issues for the development of reliable 2D MOFs and COFs with enhanced catalytic performance are discussed.

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…Benefiting from tunable structures, large specific surface areas, and well-defined nanoscale pores, heteroatom-involved COFs have been explored as ORR electrocatalysts, but their performance is constrained by the limited active site density and poor conductivity. 538 Metalation of COFs is demonstrated to be an effective approach to access COF-based ORR electrocatalysts with rich and precisely controlled electrocatalytically active sites.…”

Organic ultrathin nanostructure arrays: materials, methods and applications

“…2D polymers that are laterally infinite, one atom- or monomer-unit thin, free-standing, covalent networks with long-range order along two orthogonal directions have attracted intense attention in recent years due to their wide application in electronics, membranes and sensing. 48–50…”

Recent progress on covalent organic framework materials as CO2 reduction electrocatalysts

“…In addition, since most of the COFs are synthesized via cross-coupling or condensation reactions between organic aromatic building blocks and linkers, the whole framework has large conjugation structures and shows semiconducting properties with tunable bandgaps, which renders them good platforms for electrocatalysis (Dogru and Bein, 2014;Lin and Chen, 2018;Song et al, 2019;Cui et al, 2020;Sharma et al, 2020;Guan et al, 2021;Zhao et al, 2021;Lee et al, 2022). To further improve the conductivity, COFs could be hybridized with other conductive materials such as graphene or carbon nanotubes, and the incorporation of transition metal active sites further enhances the catalytic activity and selectivity due to synergic effect between metals and COF supports.…”