Ultrasonic-assisted synthesis of carbon nanotube supported bimetallic Pt–Ru nanoparticles for effective methanol oxidation

Abstract

In this paper, we demonstrate a facile and one-step ultrasonic method to synthesize a carboxylate functionalized multi-walled carbon nanotube supported bimetallic platinum ruthenium nanoparticle (Pt–Ru/c-MWNT) catalyst. The results show that the atomic Pt–Ru ratio is approximately 1 : 1, and the Pt mass loading in the catalyst is 8%. In addition, Pt–Ru nanoparticles with bimetallic structure, ultrasmall size (1.9 nm), and uniform distribution were well-dispersed onto the surface of c-MWNTs, which exhibit enhanced electrocatalytic performance toward methanol oxidation. It is found that this catalyst has a much higher electrochemically active surface area (ECSA) (133.2 m² g_Pt⁻¹) and current density for methanol oxidation (1236.0 mA mg_Pt⁻¹) than those of commercial Pt/C (20 wt%) (55.6 m² g_Pt⁻¹, 214.2 mA mg_Pt⁻¹). Furthermore, the oxidation current density of the Pt–Ru/c-MWNT catalyst at 10 000 s is 22.5 mA mg_Pt⁻¹, which indicates a long-term high electrocatalytic activity of the Pt–Ru/c-MWNT catalyst for methanol oxidation in acid media.