Surfactant‐Controlled Microemulsion Synthesis of Au–Pt/TiO 2 Catalysts: Linking Nanoparticle Structure to Base‐Free Glucose Oxidation

The selective oxidation of glucose to sugar acids is a key transformation in biomass valorization, yet catalytic performance remains highly sensitive to nanoparticle size, surface composition, and metal distribution. This work investigates how microemulsion structure, governed by surfactant identity, controls the formation and catalytic behavior of Au, Pt, and Au–Pt/TiO 2 nanoparticles in base‐free glucose oxidation. Two contrasting surfactants were examined: AOT (rigid ionic film) and Triton X (flexible nonionic film). TEM analysis showed that AOT produces significantly smaller and more uniform nanoparticles than Triton X (Au: 6.5 vs. 12.0 nm; Pt: 1.6 vs. 15.6 nm; Au 50 Pt 50 : 4.7 vs. 8.6 nm). STEM–EDX and XPS indicate that AOT favors compositionally heterogeneous structures with Au‐rich cores and Pt‐enriched surfaces, while Triton X leads to alloy‐like particles. These structural differences result in distinct catalytic behavior: AOT‐derived catalysts exhibit higher activity due to smaller size and greater surface accessibility. Au‐AOT achieves near‐complete glucose conversion with 88.7% selectivity toward gluconic acid, while Pt primarily tunes selectivity toward deeper oxidation products. Stability studies suggest deactivation arises mainly from surface restructuring and metal redistribution rather than sintering. Overall, surfactant‐controlled synthesis provides an effective strategy to tune activity and selectivity in Au–Pt/TiO 2 catalysts.