Confinement‑driven stabilization of Pt nanoparticles within amine‑functionalized dendritic mesoporous silica for the selective hydrogenation of 4‑nitrophenol

Amine-functionalized dendritic mesoporous silica nanospheres (DMSN‑NH 2 ) was developed to confine and stabilize Pt nanoparticles. • Pt@DMSN-NH 2 showed higher TOF (968 h −1 ) than Pt@DMSN (312 h −1 ). • Pt@DMSN-NH 2 exhibits higher k value (1.23 min −1 ) and lower Ea value (36.9 kJ·mol −1 ) than Pt@DMSN (0.298 min −1 , 46.5 kJ·mol −1 ). • The excellent performance of Pt@DMSN‑NH 2 is attributed to its dendritic architecture and amine-functionalities. • Pt@DMSN-NH 2 catalyst exhibited excellent stability for up to five consecutive cycles. Stabilizing precious Pt nanoparticles on conventional supports remains challenging, as their high surface energy makes them prone to early destabilization. In this work, Pt nanoparticles synthesized via a polyol method were uniformly dispersed and firmly anchored on dendritic mesoporous silica nanospheres (DMSN), which were fabricated through a simple hydrothermal route and later functionalized with amine groups (DMSN‑NH 2 ). Remarkably, the as-synthesized Pt@DMSN-NH 2 catalyst exhibited 4.12 times enhancement in the catalytic hydrogenation of 4-nitrophenol (4-NP), achieving significantly excellent rate constant and turnover frequency values ( k = 1.23 min −1 , TOF = 968 h −1 ), compared with those of the Pt@DMSN catalyst ( k = 0.298 min −1 , TOF = 312 h −1 ). A comprehensive investigation of the structure-activity relationship, supported by a suite of bulk and surface characterization analysis, obviously attributes the highly efficient catalytic hydrogenation behavior of Pt@DMSN-NH 2 to the dendritic mesoporous architecture and the amine functionalities lining the pore walls. These two features jointly regulate the size of Pt nanoparticles (3.2 nm) and facilitate their uniform distribution (36.2% dispersion), thereby generating a higher number of key active Pt 0 species on the surface of Pt@DMSN-NH 2 , which enhances the hydrogenation of 4‑NP. The fabricated Pt@DMSN-NH 2 showed remarkable activity in the hydrogenation of 4-Nitrophenol. Download: Download high-res image (160KB) Download: Download full-size image