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

Platinum-silver alloy nanoparticles (Pt_xAg_y 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 Pt_xAg_y 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/μg_Pt 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 Pt_xAg_y 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 Pt_xAg_y alloy in the direct methanol fuel cells (DMFCs).