Template Assisted Fabrication of Pt–Sn Core–Shell Nanospheres

Sub-micron or nano-scale spheres are typically fabricated using conventional powder metallurgy processes; however, it is difficult to control the diameter and shape of each nanoparticle such that they are uniform. In this work, tin (Sn) was first sputtered on an anodic aluminum oxide (AAO) template. Then tin spheres were formed on the AAO by sinking tin-deposited AAO into silicone oil through the thermal-reflowing process. The size and quantity of the spheres were controlled with the sputtering time and power. The thermal-reflowed tin nanospheres were subsequently coated with thin platinum (Pt) film by DC sputtering, forming Pt–Sn core–shell nanospheres. The total surface area of the tin sphere on AAO and specific surface area of the Pt spherical shell were determined. The specific surface areas of Pt shell on the Sn nanospheres were 8.1–16.2, 10.3–20.6, and 12.8–25.6 (m2 g−1) with wetting angles at 100°, 120°, and 150°, respectively between the Sn sphere an AAO.