Covalent triazine-based frameworks for multi-functional sensing-challenges, opportunities, and future directions

Covalent triazine-based frameworks (CTFs) have emerged as a class of porous organic materials with exceptional structural stability, high surface area, and tunable electronic properties, making them highly suitable for gas sensing, photoelectrochemical sensing, and electrochemical sensing applications. This review comprehensively explores the fundamental principles, material properties, and sensing mechanisms of CTFs across these three domains. The role of CTFs in gas sensing is examined with an emphasis on adsorption capabilities, conductivity variations, and selectivity toward specific gas molecules. In photoelectrochemical sensing, their photophysical properties, including light absorption, charge separation, and interfacial interactions, are discussed in the context of improving sensor performance. In electrochemical sensing, the review highlights CTFs redox-active sites, electron transfer efficiency, and catalytic activity, which enhance their utility in detecting a range of analytes. Key challenges, including sensitivity limitations, structural stability under operational conditions, and response time constraints, are critically analyzed. Finally, perspectives on overcoming these challenges through material functionalization, hybridization with nanomaterials, and advanced synthesis techniques are provided, offering insights into the future development of high-performance CTF-based sensors for environmental and biomedical applications.