Microwave Heated Synthesis of PdAg Core-Shell Nanowires for Electrochemical Oxidation of Ethanol in Alkaline Medium

Abstract

Bimetallic electrocatalysts based on Pd such as PdAg, PdNi and PdSn, have shown high efficiencies for ethanol oxidation reaction (EOR). In this study, a novel PdAg core-shell nanowire structure (PdAg-MW) with a Pd:Ag molar ratio of 1:10 was synthesized via a simple two-step process under microwave (MW) pulse mode irradiation in polyol solvent. The effect of MW irradiation time on the formation of Pd shell on Ag nanowires was investigated and compared to the sample PdAg-CP prepared by conventional polyol process. The catalytic ability and stability of the catalysts for ethanol electro-oxidation in KOH solution were examined by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) measurements. Tolerance to CO gas was also studied by CO stripping analysis. Surface morphology, structure and composition of the materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray (EDX). The results showed that PdAg-MWs possessed a unique morphology and hollow structure can be achieved at 6-8 times of MW heating. The EOR peak current value is achieved about 3156 mA/mg Pd for PdAg-MW/C, which is superior to Pd nanoparticles/C (PdNPs/C) and PdAg-CP/C, making it a promising Pd-based anodic electrocatalyst for alkaline direct ethanol fuel cells.