Green synthesis of bimetallic Pt@Cu nanostructures for catalytic oxidative desulfurization of model oil

This study reports the synthesis of bimetallic Pt@Cu nanostructures at elevated temperature of 100 C using Alchornea laxiflora leaf extract (ALLE). The nanostructures have been characterized using UV–vis spectroscopy, high resolution transmission electron microscopy (HRTEM), Fourier Transform Infrared spectroscopy (FTIR), energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction (XRD) techniques. The sizes of the bimetallic Pt@Cu nanostructures range from 1.87 to 2.38 nm with an average particle size of 2.12 ± 0.21 nm, and they crystallized in face-centered cubic (fcc) symmetry. The EDX analysis confirms the bimetallism of Pt@Cu nanostructures and individual metals are present in the ratio 2:3. FTIR indicates strong peaks at 3427 cm-1 which is attributed to hydroxyl group of polyphenolic compounds in ALLE, and the peak disappeared completely in the FTIR of Pt@Cu nanostructures, thus confirming their significant roles in bioreduction process. Catalytic oxidative property of Pt@Cu nanostructures was investigated by oxidation of a model oil [dibenzothiophene (DBT) dissolved in n-heptane] to their corresponding sulfone. Our results show that bimetallic Pt@Cu nanostructures have higher catalytic oxidative activity than the conventional acetic acid that is used in the oxidative desulfurization process. The catalytic oxidative desulfurization activity shown by the Pt@Cu nanostructures promises the potential application in petroleum industry.