Benzotriazole‐Functionalized g‐C 3 N 4 /NH 2 ‐UiO‐66 Heterojunctions Enable Photothermal Self‐Healing and Durable Polyurea Protective Coatings

ABSTRACT Protective polymer coatings for marine and island infrastructures are expected to integrate resistance to mechanical damage, chloride attack, ultraviolet aging and fungal colonization, yet achieving these functions in a single dynamic coating remains challenging. Herein, an Oct‐CUPU coating is developed by embedding a benzotriazole‐modified g‐C 3 N 4 /NH 2 ‐UiO‐66 heterostructure, denoted as Oct‐CU, into a disulfide‐containing polyurea network. The g‐C 3 N 4 /NH 2 ‐UiO‐66 heterointerface provides photothermal conversion and interfacial reinforcement; the benzotriazole moiety improves UV shielding, and the dynamic polyurea matrix supplies reversible hydrogen bonding and disulfide exchange for damage repair. These coupled molecular and interfacial interactions enable localized light‐to‐heat conversion to activate chain mobility and network reconstruction, while the rod‐like heterostructure promotes stress redistribution and improves long‐term barrier stability. As a result, the optimized Oct‐CUPU coating exhibits rapid NIR‐triggered scratch healing and markedly enhanced corrosion‐barrier retention. It also maintains improved abrasion tolerance, UV‐aging resistance, and mold resistance compared with the unmodified coatings. This work presents a heterostructure‐assisted design strategy for adaptive polyurea coatings with integrated self‐healing, anticorrosion, anti‐aging, and antifouling‐related functions, offering potential for durable protection of metallic structures in marine, coastal, and outdoor environments.