Covalent–Organic Framework (COF)‐Core–Shell Composites: Classification, Synthesis, Properties, and Applications

Abstract

Core–shell structures, where the “guest” material is encapsulated within a protective shell, integrate the advantages of different materials to enhance the overall properties of the composite. Covalent–organic frameworks (COFs) are favorable candidates for composing core–shell structures due to their inherent porosity, good activity, excellent stability, and other advantages. In particular, COFs as shells to encapsulate other functional materials are becoming increasingly popular in the fields of environmental remediation and energy conversion. However, there is a lack of reviews on COF‐based core–shell materials. In this context, this review provides a systematic summary of the current research on COF‐based core–shell composites. First, a simple classification is made for COF‐based core–shell composites. The second part of the review describes the main synthesis methods. The changes brought about by the COF shell and core–shell structures on the properties of the composites and their applications in photocatalysis, electrocatalysis, adsorption, sensing, and supercapacitors are then emphasized. Finally, new perspectives on the future development and challenges of composites are presented. The purpose of this study is to provide future insights into the design and application of COF‐based core–shell composites.

Covalent Organic Frameworks: Opportunities for Rational Materials Design in Cancer Therapy

“…Post-processing by reduction, hydrolysis, and precipitation can convert the metal ions within metalated COFs into nanoparticles (Figure 10A). [114] The well-defined pore structures of COFs restrict the growth and aggregation of metalbased nanoparticles during synthesis and use, conferring consistently high activity. In 2020, Zhang et al [115] synthesized Phos-COF-1, which could anchor multiple metal ions, including Pd(II), Pt (II), and Au(III), using P atoms in the framework.…”

Covalent Organic Frameworks: Opportunities for Rational Materials Design in Cancer Therapy

“…Post‐processing by reduction, hydrolysis, and precipitation can convert the metal ions within metalated COFs into nanoparticles (Figure 10A). [114] The well‐defined pore structures of COFs restrict the growth and aggregation of metal‐based nanoparticles during synthesis and use, conferring consistently high activity. In 2020, Zhang et al [115] .…”

Benzotrifuran-based donor–acceptor covalent organic frameworks for enhanced photocatalytic hydrogen generation

“…Covalent organic frameworks (COFs) have emerged as a new class of porous crystalline polymers by integrating functional organic building units into periodic network architectures through strong covalent bonds under reticular chemistry. 12–18 Considering structural aspects, their inherent ordered pores and large specific surface areas can provide large spaces for matter diffusion and transformation. Two-dimensional (2D) COFs offer columnar π-arrays and afford an ideal channel for photoinduced charge carrier transmission owing to the orbital overlap of stacked aromatic blocks.…”

“…Two-dimensional (2D) COFs offer columnar π-arrays and afford an ideal channel for photoinduced charge carrier transmission owing to the orbital overlap of stacked aromatic blocks. 17–23 As desirable alternatives to inorganic photocatalysts, metal-free 2D-COFs have recently received much attention in various heterogeneous photocatalysis, including photocatalytic hydrogen production. 24–34 In particular, the most important advantage of 2D-COFs is that it is easy to regulate their structure and functionality by selecting special building blocks as co-monomers and different linkages.…”

“…In addition, a series of functional organic building units such as triazine, pyrene, porphyrin, and phthalocyanine has been introduced into the frameworks to functionalise them. 17,18,21 However, designing and synthesizing novel organic structures as monomers to construct metal-free, high-performance COF-based photocatalysts with small exciton binding energy ( E b ) and high photocatalytic activity are still highly desired.…”