Electronic Structure Tailored Covalent Organic Frameworks for Synergistic Adsorptive-Photocatalytic Gold Recovery...

Electronic waste contains gold at concentrations far exceeding natural ores, yet efficient and selective recovery remains challenging. Here, we present a covalent organic framework (COF), tetra-(4-aminophenyl)-porphyrin-4,4'-(thiazolo[5,4-d]thiazol-2,5-diyl)bis(2,5-dimethoxybenzaldehyde)-COF (TAPP-TZ-OMe-COF), in which thiazole and methoxy groups create abundant AuCl₄ ^- binding sites and modulate the electronic structure via donor-acceptor interactions and p-π conjugation. These features narrow the band gap, enhance charge separation, and accelerate photogenerated electron transfer, enabling synergistic adsorption and visible-light reduction of Au(III) to Au(0). TAPP-TZ-OMe-COF delivers a gold recovery capacity of 4,109 mg g^-1 and achieves 99.9% recovery from computer processing unit-board leachate with >10⁵-fold selectivity and excellent cycling stability. This molecular-engineering approach offers a generalizable blueprint for integrating adsorption and photocatalysis in COFs, advancing the recovery of gold from complex waste streams for sustainable resource reclamation.