Stable Covalent Organic Frameworks for Photochemical Applications

Abstract

Covalent organic frameworks (COFs) are a type of intriguing crystalline porous network material which has attracted extensive research attention in many fields. In particular, the crystalline and designable structures which can be constructed with diverse building blocks and topologies endow covalent organic frameworks (COFs) with high photoconductivity and multiple potential applications in photochemistry. The chemical stability of the host COF is fundamental to guarantee the durability of the photocatalytic performance, which can be realized by robust linkages. For this reason, significant attention has recently focused on the development of stable COFs. Herein, advances achieved in the development of stable COFs for photochemical applications are described, including photocatalytic hydrogen production and reduction of CO 2 , photocatalytic organic reaction transformations, photocatalytic environmental remediation, and other applications. Furthermore, the future of COFs for application in photocatalysis are discussed.[a] L.

Photocatalytic Conversion of Lignin into Chemicals and Fuels

“…Covalent organic frameworks (COFs) are a new type of carbon‐based photocatalytic material and have received increasing attention in recent years . COFs are crystalline porous network materials connected by covalent bonds, and contain H, O, N and other elements besides C. The most attractive characteristics of COFs are the well‐ordered structures and regulable apertures, enabling them easily tailorable for desired reactions, especially for shape selective catalytic reactions .…”

Fabrication of NanoCOF/Polyoxometallate Composites for Photocatalytic NADH Regeneration via Cascade Electron Relay

“…[ 1,2 ] 2D COFs with a variety of ordered π systems provide a desirable platform for developing visible‐light responsive photocatalysts for solar energy storage and conversion and have already shown potential applications in photocatalytic water splitting, CO 2 reduction, and organic synthesis. [ 3–11 ] In regardless of suitable bandgap and band structure, COFs in most cases afforded very low quantum efficiency in photocatalysis. Considering that the separation and transportation of the photogenerated charges is the key step in photosynthesis, the fast extraction of photogenerated electrons confined in π orbitals of COFs is very important for efficient photosynthesis.…”

Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

“…Similarly, light absorption and charge transfer properties shown by aromatic COFs have recently been studied for applications in photocatalysis. Aromatic COFs usually have high absorptivity in the visible and UV spectra and show charge transfer processes consisting of electron delocalization within the conjugated structure, inducing electron-hole pair formation [ 193 ]. This phenomenon, typical of semiconducting materials, is due to the closeness between conduction and valence band energy levels, allowing for the formation of extremely reactive radical species at the surface of the material, thus initiating the photocatalytic process.…”