Electronic Structure Tailored Covalent Organic Frameworks for Synergistic Adsorptive–Photocatalytic Gold Recovery from Complex Electronic Waste
Jun Zhang, Lijuan Feng, Jiacheng Zhang, Jianfei Du, Xuewen Cao, Yan Li, Zhanhu Guo, Yihui Yuan, Ning Wang
Abstract
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 AuCl 4 − 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 >10 5 -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.