Highly active PdNi bimetallic nanocubes electrocatalysts for the ethylene glycol electro-oxidation in alkaline medium

摘要

In this work, sub 10 nm PdNi bimetallic nanocubes were used as electrocatalysts for the ethylene glycol electro-oxidation reaction (EGOR) in alkaline media. In addition, Pd nanocubes were obtained and used as reference material. Spectroscopic tests indicated that materials labelled as Pd80Ni20/C, Pd70Ni30/C and Pd60Ni40/C were obtained. High-resolution transmission electron micrographs (HR-TEM) revealed the presence of nanocubes-like shapes in all materials, being particularly abundant in Pd80Ni20/C and Pd60Ni40/C. Pd70Ni30/C presented a mixture of hemispheres and nanocubes. Average particle sizes of similar to 6 nm were determined for Pd80Ni20/C and Pd60Ni40/C, while Pd70Ni30/C had particle sizes of 5.6 nm. X-ray photoelectron spectroscopy (XPS) concluded that nickel was in form of nickel-(oxy) hydroxides (NiOOH), providing oxygenated species in the EGOR and thus, improving the electron transfer, as was corroborated by electrochemical impedance spectroscopy (EIS). In this manner, Pd70Ni30/C and Pd60Ni40/C displayed superior activity at 1 M EG + 2 M KOH than Pd nanocubes and Pd80Ni20/C, achieving current densities close to 320 mA cm(-2). In addition, the increase of temperature to 50 degrees C resulted beneficial for Pd70Ni30/C, displaying a maximum current density of 501.08 mA cm(-)(2).