Effective and selective gold recovery based on synergistic bimetallic-hydroxyl metal–organic frameworks

Efficient recovery of high-value metals such as gold from wastewater is critical for environmental remediation and sustainable resource recovery, yet it poses considerable challenges. Herein, we propose a novel design strategy that utilizes the synergistic effects of bimetallic sites and hydrophilic functionalities within a metal–organic framework for efficient gold recovery. A mechanism whereby Au(III) is directly reduced to Au(0), bypassing the formation of Au(I) intermediates, is facilitated by the bimetallic sites, as evidenced by spectroscopic analyses and theoretical simulations. Concurrently, the hydrophilic hydroxyl groups facilitate the nucleation and detachment of high-purity gold nanoparticles (∼23.9 K) without post-treatment. The Fe₁Co₁-MOF-74 synthesized using this strategy demonstrates superior performance in Au(III) adsorption, achieving a remarkable capacity of ∼ 3078.00 mg g⁻¹, high selectivity (distribution coefficient of 1.2 × 10⁷ mL g⁻¹), and a broad pH applicability (1.0–9.0), outperforming previously reported MOFs. Furthermore, the practical application of Fe₁Co₁-MOF-74 is demonstrated by the highly selective extraction of gold from complex water matrices, including river, lake, simulated seawater and central processing unit (CPU) leachate. This work offers promising strategies for sustainable gold reclamation from complex aqueous environments.