Electrochemical Nucleation and Growth of Pd-Co Alloy Nanoparticles from the Reline Deep Eutectic Solvent

Electrochemical formation of Pd-Co alloy nanoparticles, PdCoNPs, onto a glassy carbon electrode, GCE, from their metallic precursors dissolved in the reline deep eutectic solvent, is reported for the first time. Potentiodynamic and potentiostatic studies indicated that PdCoNPs were electrodeposited by multiple nucleation of 3D bimetallic centers with mass transferred-controlled growth. Potentiostatic current density transients, j-t, were adequately fitted by a theoretical model that describes the kinetics of nucleation and diffusion-controlled growth of bimetallic phases and the number density of active sites for PdCoNPs nucleation, N ₀, and their nucleation frequency, A, was determined as a function of the applied potential. SEM image recorded on the GCE electrodeposited with PdCoNPs showed that sizes and particle number density of these PdCoNPs depend on both the applied potential and the deposition time considered. At −0.42 V and 10 s the PdCoNPs had (30 ± 4) nm as average size and a particle number density of (4.23 ± 0.33) x10¹⁰ PdCoNPs cm^-2. EDS, XRD and XPS observations indicated the presence of Pd and Co. forming a PdCo alloy as zero and bivalenced oxidation states. GCE/PdCoNPs depict higher mass activity towards FAOR than GCE/PdNPs and other modified electrodes reported in the literature where the electrocatalysts were synthesized by different means.