Galvanic Replacement Incorporation of Ultrasmall Gold-Silver Nanoparticles within a Titanium Aminoterephthalate Framework.

The controlled synthesis of bimetallic alloy nanoparticles within confined environments remains a significant challenge due to aggregation, uncontrolled growth, and/or support instability, among others. Metal-organic frameworks (MOFs) offer an attractive platform to address these limitations by acting as active supports that spatially confine nanoparticle nucleation and growth. Herein, we report a galvanic replacement strategy for the formation of ultrasmall Au/Ag alloy nanoparticles (Au/AgNPs) confined within the nanometric microporous framework of MIL-125-NH2(Ti). This approach enables controlled incorporation of alloy nanoparticles both at the external surface and within the internal porosity of the MOF while preserving the crystalline structure and colloidal stability of the host framework. Comprehensive structural and compositional characterization confirms the successful formation of confined Au/Ag alloy nanostructures. The functional implications of alloy confinement are illustrated through irradiation experiments, which indicate an enhanced interaction with ionizing radiation compared to the pristine MOF. These results highlight the potential of MOF-confined bimetallic alloys as a versatile platform for applications requiring controlled nanoscale composition, stability, and interactions.