Polarisation Engineering in Covalent Organic Frameworks for Catalysis.

Polarisation in covalent organic framework (COF) catalysts has emerged as an effective strategy to reduce strong excitonic binding and to improve charge transport through built-in electric fields. Unlike conventional inorganic ferroelectrics or polar materials, COFs enable programmable polarisation through molecular and lattice design, allowing internal fields to be tuned in strength and direction. In this review, we provide a comprehensive analysis of polarisation in COFs, from its physical origins to its functional roles in catalysis. We first examine the multiscale origins of polarisation in COFs, encompassing bond-level electronic asymmetry, conjugation-mediated propagation, and framework-level structural organisation that governs dipole alignment and cancellation. We then summarise how polarisation is characterised experimentally and theoretically across different electronic and catalytic states, including ground-state electrostatic potential landscapes, photoexcited-state charge dynamics, and polarisation effects at solid-liquid catalytic interfaces. Finally, through representative photocatalytic and electrocatalytic case studies, we illustrate how deliberate polarisation engineering reshapes charge separation, transport, and reaction pathways across diverse catalytic reactions, and conclude by discussing the key opportunities and challenges for translating polarisation into a predictive design principle for COFs. By connecting the origins, characterisations, regulating strategies, and catalytic mechanisms, this review provides a more integrated perspective on polarisation phenomena in next-generation COF catalysts.