Directional Electron Transfer in Island‐Sea Structured Contact‐Electro‐Catalysis Enables Cascade Defluorination of PFAS

Abstract The exceptional stability of C─F bonds in per‐ and polyfluoroalkyl substances (PFAS) impedes their activation and degradation through conventional redox processes. Contact‐Electro‐Catalysis (CEC) offers an oxidant‐free alternative but suffers from uncontrolled electronic structures and non‐directional electron transfer. Here, we design an “island–sea” structured CEC system by embedding atomically dispersed Cu─N 4 islands within a polyvinylidene fluoride (PVDF) matrix. The Cu─N 4 domains trigger interfacial electron transfer that induces β‐phase crystallization of PVDF. The aligned dipoles amplify piezoelectric polarization and strengthen interfacial electric fields (IEFs). This configuration enables efficient electron harvesting from interfacial water and field‐emission‐driven injection into Cu─N 4 sites. The electron‐enriched Cu sites activate O 2 to form • O 2 − for nucleophilic defluorination while simultaneously populating the C─F σ* orbitals to facilitate bond cleavage. In parallel, • OH and 1 O 2 promote oxidative mineralization of low‐fluorinated intermediates, establishing a cascade redox pathway. This cooperative mechanism achieves 95% degradation and 94.4% defluorination of perfluorooctanoic acid with excellent stability. This study defines β‐phase‐mediated IEF engineering in polymer/single‐atom hybrids as a general concept for directing interfacial electron dynamics in catalytic systems.