2.1. Synthesis of Pt nanoparticles and Pt/Ni nanoalloys
Stock solutions of platinum chloride (PtCl2; 1.40 mM) and nickel chloride (NiCl2; 1.43 mM) were prepared by dissolving 5.6 mg PtCl2 and 5.1 mg NiCl2·6H2O in 15 mL diethyleneglycol (DEG), respectively, under vigorous stirring for 1 hour.
Unsupported Pt/Ni nanoalloys were synthesized in 6 steps.
First, 1 mL PtCl2 and 1 mL NiCl2 stock solutions were added to 5.5 mL DEG in a 20 mL scintillation vial and mixed by magnetic stirring for 15 minutes. Second, the vial was placed in a commercial microwave oven (R-209KK, Sharp Electronics Corp., Mahwan, New Jersey; 800 W, 2.45 GHz).
Microwave radiation was administered in 1–8 cycles, each of which consisted of a 50-second “on” segment at the maximum power followed by a 30-second “off” segment.
Third, the vial was taken out of the microwave oven and cooled in air to room temperature. Fourth, the reaction mixture was then centrifuged at 17,000 × g for 5 min to recover nanoalloys.