In Situ Formation of Pt–Au Nanoparticles on Magnetic Composites Carriers: Tuning Catalytic Activity by Incorporation of Different Metal Oxides

Abstract

Supported Pt─Au bimetal nanocatalysts have been prepared by an in situ reduction method followed by calcination in air and reduction in H2 atmosphere. The catalysts exhibit a typical yolk‐shell construction composed of a moveable magnetic Fe core and metal oxides shells decorated with Pt─Au nanoparticles. The structure of the bimetal nanocatalysts was characterized in detail by TEM, XRD, XPS, and N2 physical adsorption and the catalytic activity of the nanocatalysts was studied by the catalytic reduction of 4‐nitrophenol to 4‐nitrophenol. It is found that the bimetal nanocatalysts composed with the different metallic oxides (TiO2 and ZrO2) exhibited the comparable Pt─Au particles size (~10 nm). However, the content of Pt─Au nanoparticles was varied with the metallic oxides support. Pt─Au nanoparticles deposited uniformly on TiO2 with higher loadings, however the nanoparticles on ZrO2 exhibited remarkably lower content, which should be attributed to the abundant hydroxyl on TiO2 surface that served as the deposition site for Pt─Au nanoparticles. The result of the reduction reaction indicated that incorporation of TiO2 in the bimetal Pt─Au nanocatalyst could significantly improve the catalytic activity as compared with ZrO2 and m‐SiO2. A possible mechanism was proposed to explain the synergistic effect in the supported Pt─Au bimetal nanocatalysts.