Advances and challenges in covalent organic frameworks as an emerging class of materials for energy and environmental concerns

Covalent organic frameworks (COFs) have been extensively studied as an attractive class of crystalline porous polymers due to their structural diversity and adjustable design. COFs' adjustable properties, low densities, and large specific surface areas make them an ideal platform for various applications, including gas separation and storage, luminescence, chemical sensing, electrical devices, medicine delivery, energy conversion and storage, heterogeneous catalysis, etc. However, the primary issue in employing COFs is their exact tunability, selectivity, stability, and the need for pricey precursors, which limit their practical applications. These issues call for a quantitative assessment to collect the reported theoretical and experimental data on COFs and apply the learned lesson for further in-depth exploration of their preparation, properties, and emerging applications. Therefore, this review aims to provide an overview of the advancements in COF research to date, encompassing their designing principles, architectural inclusion, types of connections, preparation approaches, and notable applications in electrochemical energy conversion and storage, CO2 uptake, catalysis, and environmental remediation. Based on this assessment, this review identifies the current challenges and proposes suitable solutions to overcome them, paving the way for future advancements in the practical application of COFs.