Electrochemical Deposition of Pd@Pd(OH)₂Core-Shell Nanoparticles onto Glassy Carbon from a Deep Eutectic Solvent (Reline) and their Use as Electrocatalyst for the Methanol Oxidation Reaction

Pd@Pd(OH)2 core-shell nanoparticles were potentiostatically electrodeposited onto a glassy carbon electrode, GCE, from Pd(II) ions dissolved in the reline deep eutectic solvent. It is shown that the GCE/Pd@Pd(OH)2-modified electrode displays a high catalytic activity towards the methanol electrochemical oxidation reaction (MOR) in alkaline solution, revealing a mass activity of (2370 450) mA mgPd-1 at the peak potential (for CVs recorded at 0.1 V s-1), much greater than those reported to date for other nanoparticles, namely: Pd, Cu1Pd2, Pd4Ag1, PdFe, PtPdPt, Pt or Pt2Ru1, synthesized by means of technically complicated, expensive and time-consuming methods or electrodeposited from aqueous media. In particular, the steady-state current reported for PdNPs electrodeposited from aqueous media towards MOR depicted values around 3 mA mgPd-1, while those from DES (this work) reached values around 42 mA mgPd-1. Furthermore, it is shown that the Pd@Pd(OH)2 nanoparticles displayed excellent poisoning tolerances, from 2 to 8, depending on the applied potential scan rate and anodic switching potential, which remains practically constant after 200 voltammetric cycles.