Leveraging Photothermal Effect in 1D Covalent Organic Frameworks for Efficient, Rapid, and Selective Gold Recovery

Abstract

ABSTRACT The recovery of gold from electronic waste is a sustainable and eco‐friendly resource recycling strategy. However, simultaneously achieving high adsorption capacity, rapid kinetics, and exceptional selectivity remains a significant challenge. Herein, a novel approach was presented for efficient gold recovery by photothermal effect in one‐dimensional covalent organic frameworks (1D‐COFs), and TN‐COF and TC‐COF were designed and synthesized for such studies. Under visible light irradiation, they exhibited excellent AuCl 4 − adsorption capacity (3489 and 3340 mg g −1 ), ultrafast adsorption kinetics (over 99% gold removal within 20 s), good recyclability (> 25 cycles) and high selectivity ( K d > 1.0 × 10 6  mL g −1 , S q > 9.0 × 10 3 ), which enable about 99% gold recovery from waste central processing unit (CPU) leachates with only 17 ppm Au(III), ranking among the highest values reported for COF‐based adsorbents to date. Mechanistic results revealed that Au(III) was adsorbed by electrostatic and coordination interactions with multiple N and O sites, while both protonated ─NH group and photogenerated electrons efficiently reduced the adsorbed Au(III) to Au(0). By leveraging the photothermal properties of the COFs, a synergistic photoreduction‐thermal promotion strategy was established to surpass traditional exothermic adsorption, enabling rapid and high‐capacity gold recovery via an endothermic‐reduction‐driven equilibrium shift under visible light.