Controlled Growth\nof Silver Nanoparticles by Metal–Support\nInteraction for Enhanced Tandem Catalytic Oxidation of HCHO at Low\nTemperature

Bifunctional zeolite-Ag catalysts with a tandem process\noffer a\nversatile pathway for efficient HCHO removal at low temperature. The\noverall performance of tandem systems is highly sensitive to the tunable\nnature of the Ag component. Herein, we report a tandem ZSM-5||Ag/γ-Al<sub>2</sub>O<sub>3</sub> catalyst that exhibits superior low-temperature\nactivity compared to the ZSM-5||Ag/SiO<sub>2</sub> catalyst, achieving\n100% conversion at 55 °C versus 32% for the latter. This dramatic\nimprovement is attributed to the morphological variations induced\nby differences in the mobility and dispersion of supported Ag nanoparticles.\nThis process involves a complex interplay between the properties of\nmetal nanoparticles (NPs) and the supports. Combining experiments\nand advanced <i>ab initio</i> molecular dynamics simulations\n(AIMD), the control of Ag NPs growth behaviors by regulating metal–support\ninteraction (MSI) strength and surface diffusion on different supports\nis revealed. Strong MSI and high diffusion barrier on γ-Al<sub>2</sub>O<sub>3</sub> triggers the slow Ostwald ripening (OR), whereas\nweak MSI and low diffusion barrier on SiO<sub>2</sub> stimulates the\nfacile particle migration and coalescence (PMC), leading to rapid\nactivity decay. The observed activity difference is strongly related\nto the surface activation of MF intermediates and the O<sub>2</sub> molecule, which was controlled by Ag NPs size. These findings demonstrate\nthe feasibility and efficacy of controlling MSI strength for the design\nof stable and high-performance supported metal catalysts.