Porous organic polymers; an emerging material applied in energy, environmental and biomedical applications

Covalent linkages facilitate the connection of organic building blocks, thereby constructing porous organic polymers (POPs). The remarkable attributes of porous organic polymers, such as adjustable porosities, low densities, high surface specificity areas, variable compositions, convenient post-functionalization, high carbon contents, and robust chemical and thermal stabilities, make them a subject of significant interest. These polymers incorporate oxygen, nitrogen, and other non-metallic atoms, as well as extended conjugation, further enhancing their appeal. POPs can be categorized into four distinct groups: covalent triazine frameworks (CTFs), hyper-crosslinked polymers (HCPs), covalent organic frameworks (COFs), and conjugated microporous polymers (CMPs). The synthesis of POPs involves processes such as polymerization and polycondensation. In recent years, POPs have emerged as promising electrocatalysts, exhibiting favorable activity and significant progress in various electrocatalytic reactions. These reactions encompass a wide range, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), nitrate reduction reaction, hydrogen oxidation reaction, nitrobenzene reduction reaction, and benzyl alcohol reaction. The exceptional performance of POPs as electrocatalysts can be attributed to their well-preserved compositional and structural properties. This tutorial review aims to highlight the catalytic applications of POPs across multiple fields, namely environmental, energy (including water splitting and hydrogen production, fuel cells, metal-air batteries, electrochemical cells, and supercapacitors), and biomedical areas (such as drug delivery, biosensing, bioimaging, and bio-separation). Moreover, the review delves into the current challenges, and will also provide future prospects.