Isomeric Π Conjugated Covalent Organic Frameworks with Tunable Nitrogen Topologies for Integrated Gold Adsorption and Photoreduction
Qiaoli Yang, Junyi Han, Shengxu Li, Mengwei Chen, Sheng Wang, Tao Zhang
Abstract
Abstract Gold recovery from electronic waste (e‐waste) presents a significant materials challenge, as conventional systems lack structural tunability, exhibit poor metal selectivity, and fail to integrate adsorption and photoreduction functionalities effectively. Herein, we present a topology‐guided strategy based on two isomeric π‐conjugated covalent organic frameworks (COFs) (v‐2D‐COF‐Dz and v‐2D‐COF‐Pz), incorporating diazine (ortho‐N) and pyrazine (para‐N) units, respectively, for integrated gold adsorption and photoreduction. The nitrogen topology not only stabilizes the π‐conjugated backbone but also significantly modulates the frameworks’ optoelectronic and redox properties. Notably, v‐2D‐COF‐Dz exhibits a markedly higher Au 3 ⁺ adsorption capacity (2465 versus 1854 mg g −1 ), attributed to enhanced interfacial electron localization and directional charge transfer to Au 3 ⁺ centers. Both frameworks achieve over 99% gold extraction from real e‐waste leachates under visible‐light irradiation. Spectroscopic characterization and DFT analysis reveal that nitrogen topology governs metal coordination strength and electronic coupling, enabling precise Au–Cl bond activation. This work establishes a nitrogen‐topology‐directed design paradigm for light‐driven, COF‐based precious metal recovery systems.