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Article Dans Une Revue Electrocatalysis Année : 2023

Formic Acid Electrooxidation on Palladium Nano-Layers Deposited onto Pt(111): Investigation of the Substrate Effect

Résumé

The influence of Pd nano-layers electro-deposited onto Pt(111) single-crystal has been systematically studied towards the formic acid electrochemical oxidation reaction in H2SO4 and HClO4. The studied PdxML/Pt(111) surfaces (x = 1, 2, 5 and 16 monolayers –ML-) are all more active than Pt(111) towards formic acid oxidation, even if the activity is very sensitive to the Pd film thickness and morphology. In sulfate solution, the competitive adsorption of long range ordered (bi)sulfate on the pseudomorphic Pd terraces effectively hinders the formic acid oxidation only on the thinnest films. We could observe the different role of the (bi)sulfate adsorption on the first and on the following deposited Pd layers. The sulfate adsorption competitive role rapidly fades away beyond about 5ML as equivalent thickness, due to the surface roughness increasing and terraces width diminishing. In perchlorate media, anions do not adsorb competitively with formic acid intermediates, allowing a larger activity of the formic acid oxidation up to about 5ML. At higher thicknesses, the difference in activity between the two electrolytic media is reduced and it drops in both electrolytes close to 0.5 V RHE, where Pd surface oxides are formed. The outstanding activity for Pd1ML/Pt(111) observed in perchloric solution has been considered. Coupling the electrochemical results with the Pd layers structural description previously obtained from in situ SXRD experiments, we could demonstrate that the ligand effect of the underlying platinum atoms on the first pseudomorphic Pd layer plays a major role in this superior activity. This advantageous effect is lost for Pd deposits thicker than 1ML.
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Dates et versions

hal-04034823 , version 1 (27-07-2023)

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Vanessa Oliveira, Y. Soldo, Edson Ticianelli, Marian Chatenet, Eric Sibert. Formic Acid Electrooxidation on Palladium Nano-Layers Deposited onto Pt(111): Investigation of the Substrate Effect. Electrocatalysis, 2023, 14 (4), pp.561-569. ⟨10.1007/s12678-023-00816-z⟩. ⟨hal-04034823⟩
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