Hexamethoxy Triazocoronene Based Covalent Organic Frameworks: A Family of Tailored Tools for Efficient Gold Recovery

Covalent organic frameworks (COFs) have recently emerged huge prospects as new adsorption platforms for gold recovery, however, the design and construction of robust COFs with the superior capacity and kinetics is an urgent yet formidable challenge. Herein, three triazocoronene-based COFs (COF-JLU63-65) were synthesized for the first time via Schiff base polycondensation. The obtained materials combine high crystallinity, large surface area and abundant heteroatoms on the pore walls, as well as excellent photo redox properties in one structure, thereby greatly improving their adsorption performances for gold ion (Au³⁺). Significantly, COF-JLU63 shows an impressive uptake capacity of 7598 mg g^-1 with high selectivity, rapid kinetics and excellent recyclability under visible light illumination, making it the new benchmark of adsorbents for Au recovery up to now. Multiple spectroscopy and theoretical simulation demonstrate that the triazocoronene-based COF-JLU63 not only exhibits rapid adsorption and large uptake capacity for Au³⁺, but also own effective photoreduction ability for Au³⁺ into Au⁰. Such the well-matched synergistic effects in adsorption and photoreduction is crucial in enhancing the Au recovery. This work contributes valuable insights for the synthesis of high-performance precious metal adsorbents at molecular level.