Interface-engineered MOFs with optimized oxide loading: a game-changer for thorium ion capture

To address the critical challenge of improving the performance and stability of metal–organic frameworks (MOFs) for nuclear wastewater treatment, we present an innovative strategy—a progressive proportional loading approach for incorporating graphene oxide (GO) and silica (SiO₂) into the SU-102(Zr) MOF matrix. Although oxide/MOF composites have been extensively investigated, the crucial influence of oxide loading ratios—a fundamental design parameter—has been systematically neglected. Our findings indicate a nonlinear relationship between GO/SiO₂ content and the structural stability and adsorption efficiency of the composite, consistent with the ‘optimality principle’ in interfacial engineering. By synthesizing a series of x SiO₂/GO@SU-102(Zr) composites (x = 3.125, 6.25, and 12.5 wt%), we demonstrate that the 6.25 wt% loading ratio achieves unprecedented performance in highly acidic conditions (0.3 M HNO₃). This optimized composite exhibits record-breaking thorium adsorption (76.28 mg g⁻¹ (initial uptake) and 59.63 mg g⁻¹), surpassing all reported MOF-based adsorbents in such harsh environments, and exceptional stability (superior thermal and acid resistance compared to its counterparts). Density functional theory calculations elucidate the synergistic adsorption mechanisms, emphasizing the enhanced interfacial interactions between Th(IV) ions and the composite components. This study establishes a generalized design framework for oxide/MOF composites and opens new avenues for applications in nuclear waste remediation, heavy metal recovery, and advanced separation technologies. Our findings highlight the transformative potential of precision loading strategies in realizing the full capabilities of MOFs for addressing real-world environmental challenges.