Electrocatalytic oxidation of formic acid by palladium nanoparticles electrochemically synthesized from a deep eutectic solvent

L. Juárez-Marmolejo, B. Maldonado-Teodocio, M. G.Montes de Oca-Yemha, M. Romero-Romo, E. M. Arce-Estrada, A. Ezeta-Mejía, M. T. Ramírez-Silva, J. Mostany, M. Palomar-Pardavé

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6 Scopus citations

Abstract

Palladium nanoparticles (PdNPs) were formed and supported onto the surface of a glassy carbon electrode (GCE) from a single potentiostatic step using palladium chloride (PdCl2) as the precursor salt, dissolved in a deep eutectic mixture formed by 2-Hydroxy-N,N,N-trimethylethanaminium chloride (choline chloride) and diaminomethanal (urea). Analysis of the potentiostatic current density transients allows to accurately establish the amount of Pd deposited on the GCE surface required to determine the so-called mass activity, as defined by the ratio between methanoic acid (formic acid) oxidation current and palladium mass electrodeposited on the electrode. From SEM analysis of the GCE surface modified with PdNPs, it was found that PdNPs were distributed uniformly over the electrode surface, having an average size of (60 ± 9) nm. EDX and XPS analysis confirm a core-shell morphology constituted by a Pd core surrounded by a palladium (II) Hydroxide- palladium (II) oxide (Pd(OH)2-PdO) shell. The GCE modified with PdNPs (GCE/PdNPs) were used to oxidize formic acid from aqueous electrolytic baths added with perchloric acid (HClO4) or sulfuric acid (H2SO4). It was shown that the maximum mass activity depended on both, the nature of the electrolytic bath and the applied potential for the PdNPs electrodeposition. However, the best mass activity ((5085 ± 129) mA mgPd−1) was achieved with the GCE/PdNPs, formed at −700 mV vs. the silver quasi reference electrode (Ag QRE), immersed in the HClO4 electrolytic bath, even when the formic acid concentration was half that used in the H2SO4 electrolytic bath. Furthermore, the mass activities of the PdNPs reported in this work rank high among other values reported in the literature for nanoparticles based on palladium but synthesized with more complex and expensive processes, having the advantage of being obtained by a simple, rapid, and cost-effective electrochemical method.

Original languageEnglish
Pages (from-to)190-197
Number of pages8
JournalCatalysis Today
Volume394-396
DOIs
StatePublished - 1 Jul 2022
Externally publishedYes

Keywords

  • Core-shell palladium nanoparticles
  • Deep eutectic solvent
  • Electrocatalysis
  • Electrodeposition
  • Formic acid

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