Excellent Electroactivity of Ternary Pd–Ag–Sn Nanocatalysts for Ethanol Oxidation

Multi-walled carbon nanotube (CNT) supported Pd–Ag–Sn nanocatalysts including Pd/CNT, Pd 7 Ag 3 /CNT, Pd 7 Sn 2 /CNT, Pd 7 Ag 1 Sn 2 /CNT, Pd 7 Ag 2 Sn 2 /CNT and Pd 7 Ag 3 Sn 2 /CNT, have been prepared in a mixture solution of ethylene glycol and water by NaBH 4 reduction method. The samples have been characterized by using scanning electron microscopy, transmission election microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Compared to the Pd/CNT and Pd 7 Ag 3 /CNT catalysts, metal particles of the ternary Pd 7 Ag 2 Sn 2 /CNT catalyst are more uniformly dispersed on the surface of CNTs and present the size of ca. 2.4 nm. Both binary Pd–Ag and ternary Pd–Ag–Sn catalysts exhibit the alloying of Pd and Ag. Electrochemical activities of the prepared catalysts for ethanol oxidation in alkaline media were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy. Results show that Pd 7 Ag 2 Sn 2 /CNT catalyst reveals the highest current density of ethanol oxidation among the prepared catalysts and presents a high steady-state current density for ethanol oxidation from CA measurement, which is 33 times higher than the commercial Pd/C. Also, Pd 7 Ag 2 Sn 2 /CNT and Pd 7 Ag 3 Sn 2 /CNT catalysts show a large ethanol oxidation peak current density (against Pd loading) of 2.29 and 2.30 A mg −1 , indicating the high usage efficiency of Pd particles for ethanol oxidation. Graphical Abstract