Synthesis and characterization of Pt magnetic nanocatalysts with a TiO2 or CeO2 layer

Abstract

The Pt magnetic nanocatalysts with a TiO₂ or CeO₂ layer have been fabricated successfully. The mSiO₂/Pt/MO_x/Fe hybrids have a CeO₂ or TiO₂ layer synthesized through hydrothermal methods and a moveable magnetic Fe core constructed by hydrogen reduction. The obtained nanocapsules were characterized by several techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersion X-ray analysis (EDX). The catalytic evaluation was tested on the reduction of 4-NP to 4-AP monitored by UV-Vis spectroscpoy. The mesoporous SiO₂ shell served as an effective barrier to prevent the migration and aggregation of Pt NPs during calcination. Besides, the oxide layers have an apparent co-catalysis effect to improve the catalytic activity. The mSiO₂/Pt/MO_x/α-Fe₂O₃ samples were calcined at different temperatures and the final samples exhibited entirely different catalytic activity. Additionally, a possible mechanism was proposed to explain the results. Furthermore, the synthesized mSiO₂/Pt/MO_x/Fe hybrids could be easily recycled using a magnet and the catalytic activity did not decrease obviously after five runs.