Synthesis of dendrimer-templated Pt nanoparticles immobilized on mesoporous alumina for p-nitrophenol reduction

Abstract

Hydroxyl-terminated fourth-generation poly(amidoamine) (G4-OH PAMAM) dendrimers were employed as templates to encapsulate Pt nanoparticles with small size and uniform dispersion, and then Pt nanoparticles were deposited on mesoporous alumina via self-assembly between the dendrimers and the support. The decomposition of dendrimer templates was investigated in nitrogen at different temperatures. The obtained catalysts were characterized through several techniques, such as transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), nitrogen adsorption–desorption isotherms, energy dispersion X-ray analysis (EDX), X-ray diffraction (XRD) and UV-vis spectra. Compared with the catalyst calcined in air, Pt nanoparticles exhibited uniform dispersion and small size when roasted in flowing nitrogen at 550 °C. The catalytic performances of fabricated Pt/MA catalysts were evaluated through the reduction of p-nitrophenol with NaBH₄. It was found that the catalyst calcined at 550 °C in nitrogen exhibited the best catalytic activity. Besides, the catalyst was easily recycled without a marked decrease of the catalytic performance.