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For the first time, electrochemical formation of Pd-Co alloy nanoparticles (PdCoNPs) on a glassy carbon electrode (GCE) from their metallic precursors dissolved in the reline deep eutectic solvent is reported. 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 (N0) and their nucleation frequency, A, was determined as a function of the applied potential. Scanning electron microscopy imaging of 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.

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The Deep Eutectic Solvent (DES) reline have as relevant advantage that it is indeed economical, and that the urea as a separate component displays little toxicity or citotoxicity that makes it usable in numerous applications. For instance, in the study of monometallic and bimetallic systems where the reline served as the electrolyte, the electrochemical techniques: Cyclic Voltammetry (CV) and Chronoamperometry (CA) were used. Presently, the main aim is to obtain the reduction and oxidation potentials of Pd, Zn and Pd-Zn and to characterize the deposits to establish the resulting morphologies, size and composition, using scanning electron microscopy and X-ray energy dispersive spectroscopy (SEM-EDS).

In this project, the process of Pd-Co bimetallic electrodeposition on glassy carbon was studied using a choline chloride and ethylene glycol deep eutectic solvent (DES) at a temperature of 25 °C. The methodology applied for the electrochemical study comprised usual electrochemical techniques such as cyclic voltammetry (CV) and Chronoamperometry (CA). The latter showed the alloy reduction peaks, as well as the potential interval and sweep rates where a satisfactory response of the deposits was established. In addition, the type of nucleation of the alloy NPs is presented through theoretical models, as well as the value of the (apparent) diffusion coefficient, numerical density of active sites and nucleation frequency. Finally, the conclusions obtained prove that the DES used was as an optimal medium that favored the electrodeposition of the Pd-Co alloy.

In the present work, the kinetic parameters from the electrodeposition of bimetallic Pd-Ni nanoparticles on the surface of a glassy carbon electrode (GCE) were studied. These parameters are P1 directly related to the diffusion coefficient (D), P2 related to the numerical density of active sites (N0) and the nucleation frequency (A). In addition, the type of nucleation that occurs in electrodeposition, instantaneous or progressive. The electrolytic medium used was an ethaline deep eutectic solvent (DES) for electrodeposition due to its good electrochemical properties. Cyclic voltammetry (CV) and potentiostatic current density transients (j-t) were performed at two temperatures, 25 and 70 °C. The j-t values ​​were used to generate theoretical fittings using the Scharifker and Hills, and the Díaz-Morales models for bimetallic phases.