Precision Synthesis of Sub-3 nm Bimetallic Alloy Nanoparticles for Efficient and Selective Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

Miniaturizing bimetallic alloy nanoparticles to sizes below the 3 nm threshold holds great potential to achieve distinct catalytic properties compared to single atoms and larger nanoparticles. However, conventional synthesis methods, including impregnation and nanocluster chemistry, often yield ultrasmall alloy nanoparticles with widely varied sizes or compositions. Herein, we introduce a thermodynamically driven mechanism for the precision synthesis of ultrasmall bimetallic alloy nanoparticles. Metal precursors are uniformly distributed into nanoscale compartments within a microemulsion at equilibrium. After solidifying these nanocompartments, stoichiometric metal alloying is achieved at elevated temperatures. Consequently, homogeneously alloyed bimetallic nanoparticles are synthesized within the sub-3 nm region with high precision in both size and composition. The precision synthesis enables the exploration of size- or composition-dependent catalytic properties. Notably, 1.2 nm-Pt3Co alloy nanoparticles exhibited optimal performance, outperforming other sizes (0.7–3.2 nm) and reported catalysts in the chemoselective hydrogenolysis of 5-hydroxymethylfurfural to 2,5-dimethylfuran, achieving a turnover frequency of 9733 h–1 with ∼100% selectivity. This synthesis unlocks a realm of sub-3 nm bimetallic alloy catalysts with precisely designable properties, holding significant promise for various catalytic processes.