International audienceGold nanoparticles (AuNPs) were deposited onto glassy carbon (GC) by constant potential electrolysis (CPE) using various sets of potential and duration from -0.3 to 0.7 V and 10 to 1800 s, respectively. The physico-chemical characteristics of the as-obtained deposits were investigated by cyclic voltammetry (CV) in H2SO4, field emission gun scanning electron microscopy (FEG-SEM), and Pb underpotential deposition (UPD). Their performances towards the oxygen reduction reaction (ORR) in a NaCl-NaHCO3 (0.15 M / 0.028 M, pH 7.4) neutral solution were examined and correlated to AuNPs size and density. The best results were obtained using the deposits which exhibited a high density (555 +/- 49 µm-2) of relatively small AuNPs (25 +/- 12 nm). The Koutecky-Levich treatment was systematically applied to all the deposits in order to determine the number of electrons n exchanged for the ORR in the potential range from 0.1 to -1 V. The values of the cathodic transfer coefficients Beta n were also extracted and compared to the values reported for unmodified GC and bulk Au. A map of the Beta n values as a function of AuNPs electrodeposition potential and duration was also provided
International audienceGold nanoparticles (AuNPs) were prepared by chemical route using 4 different protocols by varying reducer, stabilizing agent and solvent mixture. The obtained AuNPs were characterized by transmission electronic microscopy (TEM), UV-Visible and zeta potential measurements. From these latter surface charge densities σ were calculated to evidence the effect of the solvent mixture on AuNPs stability. The AuNPs were then deposited onto glassy carbon (GC) electrodes by drop-casting and the resulting deposits were characterized by cyclic voltammetry (CV) in H2SO4 and field emission gun scanning electron microscopy (FEG-SEM). The electrochemical kinetic parameters of the 4 different modified electrodes towards oxygen reduction reaction (ORR) in neutral NaCl-NaHCO3 media (0.15 M / 0.028 M, pH 7.4) were evaluated by rotating disk electrode voltammetry and subsequent Koutecky-Levich treatment. Contrary to what we previously obtained with electrodeposited AuNPs [Gotti et al., Electrochim. Acta 2014], the highest cathodic transfer coefficients β were not obtained on the smallest particles, highlighting the influence of the stabilizing ligand together with the deposits morphology on the ORR kinetics
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