Pt nanoparticles-engineered metal-organic framework encapsulated by a covalent organic framework shell for self-powered photoelectrochemical sensing of carbendazim.

To address the food safety risks caused by carbendazim (CBZ) residues, a high-efficiency self-powered photoelectrochemical (PEC) sensing platform was constructed for sensitive detection of CBZ. We present a PEC sensing interface based on a Pt nanoparticles-engineered ZIF-8 core encapsulated by a covalent organic framework (COF) shell (Pt NPs-ZIF-8@COF). Distinct Pt integration pathways were evaluated, revealing that in situ encapsulation of Pt NPs during ZIF-8 crystallization (Pt NPs-ZIF-8) mitigates particle aggregation and outperforms post-synthetic decoration of Pt NPs onto post-synthetic ZIF-8 (Pt NPs/ZIF-8). The COF overlayer further tailors the interfacial microenvironment by establishing a continuous charge-transport network, which together accelerate photogenerated charge separation and interfacial electron-transfer processes. Benefiting from these synergistic features, the resulting PEC sensor enables quantitative CBZ determination over a wide linear range from 1.0 × 10- 8 to 1.0 × 10- 2 µg/mL, with an ultralow detection limit of 3.3 × 10- 9 µg/mL. This work underscores a modular nanoparticles-in-MOF plus COF encapsulation strategy for building high-performance PEC biosensing interfaces and offers a promising route toward rapid pesticide-residue monitoring.