Graphene‐Like Covalent Organic Framework with a Wide Band Gap Synthesized On Surface via Stepwise Reactions

Abstract

Developing graphene‐like two‐dimensional materials naturally possessing a band gap has sparked enormous interest. Thanks to the inherent wide band gap and high mobility in the 2D plane, covalent organic frameworks containing triazine rings (t‐COFs) hold great promise in this regard, whilst the synthesis of single‐layer t‐COFs remains highly challenging. Herein, we present the fabrication of a well‐defined graphene‐like t‐COF on Au(111). Instead of single/multiple‐step single‐type reactions commonly applied for on‐surface synthesis, distinct stepwise on‐surface reactions, including alkynyl cyclotrimerization, C−O bond cleavage, and C−H bond activation, are triggered on demand, leading to product evolution in a controlled step‐by‐step manner. Aside from the precise control in sophisticated on‐surface synthesis, this work proposes a single‐atomic‐layer organic semiconductor with a wide band gap of 3.41 eV.

Structure–performance correlation guided applications of covalent organic frameworks

“…Monitoring constitutional variation process is beneficial to gain insight into the synthesis process of COFs. Well-defined graphene-like single-layer COFs with triazine rings (t-COFs) have also been manufactured on Au (111) [96].…”

Recent progress in on-surface synthesis of nanoporous graphene materials

“…N-doped NPG obtained via on-surface synthesis was first reported by Grill et al in 2007, wherein porphyrin-based 2D networks were obtained via Ullmann coupling between the tetra(4-bromophenyl)porphyrin precursor molecules 109 . Shi et al synthesized the NPG containing periodic triazine rings 110 . Several steps of hierarchical reactions, including alkynyl cyclotrimerization, C–O bond cleavage, and C–H bond activation, were used to fabricate the 2D network.…”

Recent Progress in Conjugated Polymers-Based Donor–Acceptor Semiconductor Materials for Photocatalytic Hydrogen Evolution from Water Splitting

“…COFs, as organic polymers with periodic arrangement, are usually formed by condensation of monomers with specific geometric structure, which usually have high crystallinity and high porosity. COFs consist of selected organic building blocks via covalent bond linkages such as imine [69], imide [70], boronic-ester [71], triazine [72], hydrazone [73], and C = C [74] linkages. They exhibit high thermal and chemical stability due to robust covalent bond connections between the structural units relying on the size of building blocks; two-dimensional (2D) or three-dimensional (3D) COFs can be constructed.…”