Preparation of platinum-silver alloy nanoparticles and their catalytic performance in methanol electro-oxidation

Abstract

Platinum-silver alloy nanoparticles (PtxAgy NPs) were synthesized in a molten salt system without using any organic surfactants or solvents; the catalytic role of Ag in the methanol electrooxidation reaction (MOR) in alkaline electrolyte over PtxAgy NPs was investigated. The TEM images suggest that Pt52Ag48 nanotubes (NTs) can be obtained when the Pt/Ag ratio in the molten salt precursor reaches 1. The methanol electrooxidation reaction test results indicate that the Pt52Ag48 NTs with a clean surface exhibits a much better catalytic performance than the conventional Pt black in MOR. Meanwhile, the catalytic activity of the Pt52Ag48 NTs is greatly related to the positive potential limit; the peak current of MOR reaches 1.61 mA/μgPt with a positive potential limit from –1.0 to 0.5 V (vs. SCE), which is 1.92 times higher than that with a positive potential limit from –1.0 to 0.1 V (vs. SCE). The Ag element in the surface layer of PtxAgy alloy may promote the MOR through a redox process during the electrochemical cycle. The insight shown in work should be beneficial to the application of PtxAgy alloy in the direct methanol fuel cells (DMFCs).