Co (II) Boron Imidazolate Framework with Rigid Auxiliary Linkers for Stable Electrocatalytic Oxygen Evolution Reaction

Abstract

Metal–organic frameworks (MOFs) have significant potential for practical application in catalysis. However, many MOFs are shown to be sensitive to aqueous solution. This severely limits application of MOFs in electrocatalytic operations for energy production and storage. Here, a Co (II) boron imidazolate framework CoB(im) 4 (ndc) 0.5 ( BIF‐91 , im = imidazolate, ndc = 2,6‐naphthalenedicarboxylate) that is rationally designed and successfully tested for electrocatalytic application in strong alkaline (pH ≈ 14) solution is reported. In such a BIF system, the inherent carboxylate species segment large channel spaces into multiple domains in which each single channel is filled with ndc ligands through the effect of zeolite channel confinement. These ligands, with strong C—H···π interaction, act as a rigid auxiliary linker to significantly enhance the structural stability of the BIF‐91 framework. Additionally, the π‐conjugated effect in BIF‐91 stabilizes dopant Fe (III) at the atomic scale to construct Fe‐immobilized BIF‐91 ( Fe@BIF‐91 ). Due to the synergistic effect between Fe (III) guest and Co (II) in the framework, the Fe@BIF‐91 acts as an active and stable electrocatalyst for the oxygen evolution reaction in alkaline solution.

Two‐Dimensional Metal–Organic Frameworks‐Based Electrocatalysts for Oxygen Evolution and Oxygen Reduction Reactions

“…[ 58 ] 2,6‐naphthalene dicarboxylate ligand with strong C–H– π interaction can be used as a rigid auxiliary ligand to effectively improve the structural stability of the MOFs. [ 59 ] Its coordination configuration is similar to that of BDC.…”

Co-Heteroatom-Based MOFs for Bifunctional Electrocatalysts for Oxygen and Hydrogen Evolution Reactions

“…With regard to transition-metal-based electrocatalysts, Co and Ni were considered as the active centers for the OER and HER in general. − Meanwhile, it is widely acknowledged that N/S played important roles in electrocatalysis. ,,− Compared with Co-MOFs, with the dopant of Ni­(II), the pristine Co-MOFs increased active edge sites and exposed more active sites to the reaction media, contributing to promote electrical conductivity and accelerate the electron transfer. For example, more active sites may activate H 2 O molecules by binding the OH – group in the Ni@Co-MOFs electrocatalytic process.…”

“…Especially, d metal (Fe, Co, Ni, Cu)-based MOFs exhibited high activity for electrocatalysis such as OER, HER, and carbon dioxide reduction reaction. , Unfortunately, MOFs are usually unstable in acid/basic environments, hindering their further application in electrocatalysis. Because MOFs (e.g., ZIFs and HKUST-1) were synthesized by basically choosing Zn 2+ /Co 2+ /Cu 2+ and organic ligands including imidazole, pyridine, and carboxylate moieties, however, the large porous structure reduces the strength of the coordination bond. , So far, only a handful of pristine MOFs as electrocatalysts were explored. ,− In order to design MOF-based OER and HER bifunctional electrocatalysts, the chemical stability, electrical conductivity, and active sites should be considered. Therefore, search of high-efficient and bifunctional MOF electrocatalysts including active metals (Ni, Co) and heteroatoms (N, S) is of great research interest.…”

Zeolite-Like Boron Imidazolate Frameworks (BIFs): Synthesis and Application

“…The efficiency of the bimetallic systems in the form of Co-based BIF matrices with incorporated Fe 3+ ions was also demonstrated by modifying the Co-based BIF-91 matrix (Table 1) with mixed boron imidazolate and phenylene carboxylate linkers similarly to the BIF-89 matrix [40]. Note that unlike the BIF-89 framework, the BIF-91 structure has electrocatalytically active sites, i.e., Co 2+ ions as coordination centers in the framework.…”

“…As zeolite-like MOF structures, BIF matrices are composed of topologically zeo-mimetic nets based on three-or four-connected boron imidazolate ligands. Uniformly distributed 3/4-connected boron components that are three-or four-connected boron imidazolate linkers maintain the framework integrity [40]. According to the modular synthesis principles, the pre-synthesized three- Representative crystal structures of ZIFs (the first three capital letters under each example stand for the zeolite structure code).…”