▎ 摘　　要

This work investigates the electrochemical activity of binary Pt-Sn nanoparticles onto graphene nanosheets (GNs), prepared by using a pulse microwave method. The microwave deposition offers a facile way to coat well dispersion of Pt-Sn catalysts onto GNs within a short period, i.e., < 15 min in this study. Confirmed by the Vegard's law, the Pt-Sn catalyst (with Pt:Sn ratio = 75:25) displays the highest degree of alloying of 42.8%, indicating a well-mixed atomic arrangement in the solid solution. On the Pt-Sn alloy catalyst, the Pt site is major contributor toward hydrogen adsorption, oxygen reduction, and methanol oxidation, while the neighboring Sn site acts as a promoting center for stripping oxygenate species (e.g., Pt-(CO) ads sites), leading to fast reaction kinetics. This promoted activity is attributed to the homogeneity of Pt-Sn pairs in the solid solution, capable of reducing the required potential for water electrolysis. The bi-functional design also enhances high-level of CO tolerance and long-term durability in methanol oxidation. Experimental results reveal that the Pt-Sn@GNcatalystscouldbeapromisingcandidateforcatalysisapplications(Sn ratio = 7), based on (i) appropriate ratio of Pt: Sn and (ii) high alloying degree. (C) 2014 Elsevier Ltd. All rights reserved.