Synergistic Engineering of Interfacial, Electronic, and 3D Structures in Spent Graphite Anodes for Selective Photocatalytic Silver Recovery

Selective separation and recovery of precious metals with sustainable solar energy via adsorption and photocatalytic reduction processes has emerged as a promising green and low-carbon technology with significant advantages compared to traditional hydrometallurgy and pyrometallurgy methods. Developing low-cost photocatalytic materials with favorable electronic and interfacial structures remains a critical challenge. Herein, we successfully constructed chlorine-hybrid graphene oxide (GO-Cl) via a simple oxidation-chlorination process using low-value spent graphite from lithium-ion batteries. Benefiting from the exceptional electronic structure and favorable interfacial structure of GO-Cl, a state-of-the-art high saturation Ag+ adsorption capacity of 1182.46 mg g–1 has been achieved with high adsorption selectivity from artificial Ag+-contaminated wastewater. Further integrating the GO-Cl within polyurethane foam (PUF), we fabricated a three-dimensional (3D) photocatalytic GO-Cl@PUF foam. When the 3D GO-Cl@PUF foam is incorporated into a custom continuous-flow cyclic photocatalytic reactor, it enables highly selective and stable cyclic Ag+ recovery efficiencies from waste LED and mineral leachates with a broad range of Ag+ concentrations. A comprehensive mechanistic study reveals that Ag+ undergoes an adsorption-reduction-crystallization reaction pathway at the GO-Cl interface under light irradiation. The present study not only introduces a novel approach for recovering and engineering low-quality waste graphite from spent lithium-ion batteries for photocatalytic 3D GO-Cl@PUF foam fabrication but also offers valuable insights into sustainable and selective redox-active critical metals recovery from complex solid matrixes, paving the way for developing solid waste materialization and sustainable critical metal recovery techniques.