Ethanol Electrooxidation Catalyzed by Tungsten Core@Palladium Shell Nanoparticles

Abstract

Bimetallic nanostructures represent effective electrocatalysts toward a number of important reactions. In the present study, carbon-supported palladium-tungsten alloy nanoparticles with a quasi-tungsten core@palladium shell structure (W@Pd/C) were synthesized by a galvanic replacement reaction of amorphous tungsten nanoparticles with Pd(II) at different temperatures (0, 25, and 50 °C), and exhibited apparent electrocatalytic activity toward ethanol oxidation reaction (EOR). When the sample was prepared at 0 °C, large amorphous tungsten nanoparticles were etched off and much smaller W@Pd nanoparticles were formed and dispersed rather evenly on the carbon surface whereas at higher reaction temperatures (25 and 50 °C), the W@Pd nanoparticles became agglomerated. The structures of the obtained samples were characterized by a range of experimental tools, including (scanning) transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical methods. Among the series, the W@Pd/C sample prepared at 0 °C was observed to exhibit the best EOR performance, with a mass activity (9535.5 mA mg_Pd^-1) over three times better than that of commercial Pd/C and markedly enhanced stability.