Gradient Vacancies Coupling Node Repair Boost Piezo‐Photocatalysis in Nitrogen‐Enriched Carbon Nitride

ABSTRACT Defect engineering in carbon nitride often compromises structural integrity and charge kinetics. Herein, we propose a gradient‑vacancy‑coupled node‑repair strategy realized by simple heating to overcome these limitations in nitrogen‑enriched carbon nitride (C 3 N 5 ). Experimental and theoretical simulations reveal that nitrogen vacancies preferentially form in the bulk phase, while carbon vacancies dominate the surface, resulting in a gradient vacancy architecture. High‑temperature annealing simultaneously etches vacancies and repairs fragmented nodes through ammonia release, producing C 3 N 5 ‑700 with enhanced crystallinity and a strain‑tunable built‑in electric field. Moreover, the material exhibits high stress tolerance, enabling efficient adsorption and activation of key substrates under varying strain. In‑situ photoelectric characterization and theoretical simulations confirm that the combined modifications from gradient vacancies and node‑repair cooperatively enhance charge‑carrier kinetics and surface activity. Thus, C 3 N 5 ‑700 exhibits outstanding piezo‑photocatalytic performance, achieving a tetracycline degradation rate constant of 0.047 min −1 under optimal conditions, which further increases to 0.267 min −1 in an Fe 3+ ‑triggered piezo‑photocatalytic self‑Fenton system. Meanwhile, the H 2 O 2 production rate reaches 19.23 mM g −1 h −1 (10% EtOH, pH 1). This work provides a dual‐functional defect‐repair strategy for low‑cost synthesis of piezo‐photocatalysts, which are expected to harness ambient mechanical and solar energy for water‑pollutant remediation, such as in‑situ elimination of antibiotics in rivers.