Chapter 6: COF-based Catalysts for Hydrogen Production

In recent years, solar-driven hydrogen generation has attracted significant attention because of its eco-friendly and economically viable nature. Numerous photocatalytic systems have been developed, utilizing metal compounds and amorphous polymers. However, these systems have faced limitations due to their inherent structural drawbacks, which necessitates the exploration of a novel group of materials designed for use in photocatalytic applications. Covalent organic frameworks (COFs), a novel class of highly structured organic polymers with multiple vacancies, have seized the spotlight among researchers. Their exceptional structural uniformity, resilient framework, excellent stability, high crystallinity, and innate porosity make them particularly noteworthy. COFs feature flexible architecture and multilayer stacking configurations, resulting in reduced band gaps and efficient absorption of solar energy. Moreover, their extended π-conjugation in both two- and three-dimensional frameworks plays a crucial role in promoting electron transfer and transport. The synthesis of COFs has made significant advancements, offering substantial potential for functionalization, and researchers have extensively explored their utility as photocatalysts for hydrogen production. Consequently, a multitude of research endeavours have been undertaken to assess the photocatalytic activities of COF-based photocatalysts. This chapter details the design principles of COF synthesis, the linkage chemistry of COFs, and emphasizes the potential of COF-based catalysts in the realm of photocatalytic hydrogen production applications.