Donor–Acceptor Covalent–Organic Frameworks Based on Phthalimide as an Electron-Deficient Unit for Efficient Visible-Light Catalytic Hydrogen Evolution

Abstract

Donor−acceptor two-dimensional covalent−organic frameworks (COFs) have great potential as photocatalysts for hydrogen evolution because of their tunable structures, ordered and strong stacking, high crystallinity, and porosity. Herein, an acceptor unit, namely phthalimide, has been employed for the first time to construct COFs. Two donor−acceptor COFs (TAPFy-PhI and TAPB-PhI) have been successfully synthesized via a Schiff base reaction using phthalimide as the acceptor and 1,3,6,8-tetrakis(4-aminophenyl)pyrene (TAPFy) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as donors. The synthesized COFs exhibited high crystallinity, permanent porosity, excellent chemical stability, suitable band gaps, and broad visible-light absorption. In the presence of ascorbic acid (sacrificial reagent), the TAPFy-PhI COF exhibited an efficient photocatalytic performance with a hydrogen evolution rate of 1763 μmol g −1 h −1 . Moreover, the photocatalytic performance was further improved by the addition of Pt (1 wt %) as a cocatalyst, and the hydrogen evolution rate reached 2718 μmol g −1 h −1 .

Recent progress on covalent organic frameworks for photocatalytic hydrogen generationviawater splitting

“…6). 92 The planar structure of the fused aromatic rings and strongly electron-deficient imide groups in phthalimide (PhI) promoted the π–π overlap and intermolecular interactions. The HER of TAPFy-PhI COF is up to 2718 μmol g −1 h −1 under visible light (>420 nm) irradiation.…”

A Nickel-Doped Two-Dimensional Covalent Organic Polymer (2D-COP) for Electrocatalytic Hydrogen Evolution Reaction

“…In recent decades, there has been exploration into the development of platinum-free metal-based catalysts, such as transition metal oxides, carbides, , nitrides, sulfides, selenides, phosphides, , and hydroxides. , Unfortunately, many of these catalysts exhibit high onset overpotentials (η), Tafel slopes, and poor reliability. Consequently, research groups are actively developing catalysts employing metal-containing and metal-free materials and complexes as electro- and photocatalysts to reduce water to produce molecular hydrogen. − Parameters such as oxidation and reduction sites, redox potentials, and electronic structures play crucial roles in the development of more efficient catalysts for H 2 evolution. These catalysts improve electron transfer by lowering the energy gap, hence enhancing their catalytic performance.…”

Cyanide‐based Covalent Organic Frameworks for Enhanced Overall Photocatalytic Hydrogen Peroxide Production

“…[11,[13][14] One important development in the field is the emergence of rational design of donor-acceptor (DÀ A) type COFs. [15][16][17] The introduction of DÀ A junction can lead to enhanced separation efficiency of electron-hole pairs and prevent the recombination of the carriers caused by excitonic effect. [18] Furthermore, within the framework of DÀ A type COFs, the building blocks still exhibits a structural and functional flexibility which enabling precise customization of its electronic properties.…”