Surface composition-tunable octahedral PtCu nanoalloys advance the electrocatalytic performance on methanol and ethanol oxidation

Abstract

The synthesis of surface composition-tunable Pt-based octahedral nanoalloys is key to unravel the structure-property relationship in fuel cells. Herein, we report a facile route to prepare composition-tunable PtCu octahedral nanoalloys by using halogen ions (Br- or/and I-) as composition modulators. Among these PtCu octahedral nanoalloys, Pt59Cu41 octahedron exhibits the highest catalytic activity and durability in alkaline solution. The specific activity/mass activity of Pt59Cu41 octahedron is 20.25 mA cm-2/3.24 A mg-1Pt, which is 6.64/5.3 times higher than commercial Pt black in 0.5 mol L-1 CH3OH, respectively. In the case of using ethanol (0.5 mol L-1) as fuel source, Pt59Cu41 octahedron shows much better catalytic activity, that is 34.84 mA cm-2/5.58 A mg-1Pt for specific activity/mass activity, which is 9.16/7.34 times higher than commercial Pt black, respectively. In situ Fourier transform infrared spectroscopy is employed to detect the intermediate species and products for methanol/ethanol oxidation reaction and a plausible mechanism is proposed to explain the improved activity and durability of Pt59Cu41 octahedron toward methanol/ethanol oxidation in alkaline medium.