Abstract
The heterogeneous surface of three-dimensional (3D) nanomaterials allows to increase the electrocatalytic activity for alcohols oxidation due to the presence of surface defects with high reactivity. In this work, 3D Pd and Pt materials were synthesized through electrodeposition directly on 3D tubular carbon porous electrodes (labeled as Pd/3D-C and Pt/3D-C) and then, used as electrocatalysts for the ethylene glycol electro-oxidation reaction (EGOR). Pd/3D-C was found in form of a hierarchical growth of Pd branched particles (∼28.5 nm) with missing rows, while Pt was in form of a thin film composed by sub <20 nm rosette-like 3D nanoparticles (∼11.5 nm). Thermogravimetric curves indicated that metal loadings of 134.56 and 198.37 μg cm−2 were achieved by electrodeposition for Pd/3D-C and Pt/3D-C. The chemical surface analysis performed by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy revealed that the surface atomic % of Pt was 4.9/4.4 higher to that of Pd, which was attributed to the difference in particle size/shape and surface coverage. The electrocatalytic tests indicated that both materials had an activity trend of 0.5 M KOH > 0.5 M NaOH > 0.5 M LiOH > 0.5 M H2SO4. After optimization of parameters like the KOH and EG concentration, Pd/3D-C and Pt/3D-C displayed overpotentials of 390 and 320 mV from the difference between the thermodynamic potential (0.11 V vs. RHE) and the onset potentials. Additionally, the current density was always higher in Pd/3D-C indicating a higher reactivity of its active sites. The stability tests revealed that Pd/3D-C maintained the active surface area (77.56 vs. 49.93%) and activity (112.04 vs. 39.48%) after 500 cycles in comparison with Pt/3D-C.
Published Version
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