Design and modification strategies of covalent organic frameworks for photocatalytic hydrogen/hydrogen peroxide production

Abstract

Amidst escalating environmental degradation and energy crises, the pursuit of renewable energy alternatives to fossil fuels has become a global imperative. Covalent organic frameworks (COFs), as emerging crystalline porous materials, demonstrate exceptional capabilities in solar-to-chemical energy conversion through the generation of clean fuels like molecular hydrogen (H₂) and hydrogen peroxide (H₂O₂). The development of efficient semiconductor photocatalysts is pivotal for advancing next-generation energy technologies. This study presents a systematic analysis of the four critical rate-determining steps in COFs photocatalysis: (1) photon absorption, (2) exciton dissociation, (3) charge carrier diffusion and complexation, and (4) surface redox reactions. The kinetic constraints and thermodynamic barriers associated with H₂/H₂O₂ production by COFs-based photocatalytic systems are critically evaluated, with particular emphasis on advanced regulation strategies: (i) enhancing light-harvesting through conjugated structure optimization and external sensitization, (ii) promoting exciton dissociation via Förster resonance energy transfer and localized electronic structure modulation, (iii) strengthening charge separation via crystallinity engineering and polarized field enhancement, and (iv) increasing surface active sites through microenvironment tailoring and cocatalyst integration while reducing reaction energy barriers via pH optimization. Finally, current challenges and future design paradigms for constructing COFs with enhanced photocatalytic performance are critically analyzed, with special consideration of stability-activity trade-offs and scalable synthesis protocols.