Unraveling the roles of Au in Au-Pt/MgFe2O4 for boosting catalytic oxidation of highly toxic CO

Abstract

The catalytic oxidation technique has been generally acknowledged as an extremely effective way of removing highly toxic CO, where the key is to develop catalysts with high activity as well as stability. In this work, the MgFe₂O₄ supported monometallic Pt-based and Au-based catalysts as well as bimetallic AuPt catalysts have been prepared through a sol-immobilization method and applied to the oxidation reaction of highly toxic CO. It was found that adding an appropriate amount of Au (0.6 wt.%) to 1Pt/MgFe₂O₄ significantly enhances its catalytic activity and stability. During the stability test of 20 h, the 0.6Au-1Pt/MgFe₂O₄ catalyst demonstrated high and stable CO conversion of 100 % at 165 °C and WHSV = 30,000 mL g_cat.⁻¹ h⁻¹. Various characterization techniques such as ICP, XRD, STEM, EDS, XPS, and CO-TPD reveal that the bimetallic nanoparticles composed of Au and Pt have formed in bimetallic Au-Pt/MgFe₂O₄ catalysts, where Pt donates electrons to Au. A more positive electronic state of Pt in 0.6Au–1Pt/MgFe₂O₄ and 1Au–1Pt/MgFe₂O₄ helps to reduce the adsorption strength of CO on catalysts, resulting the better CO oxidation performance compared with monometallic 1Pt/MgFe₂O₄ catalyst. These insights into the crucial structure needed for highly active and stable Pt catalysts in CO oxidation will contribute to designing even more excellent catalysts for CO oxidation in the future.