Simple, controllable and environmentally friendly synthesis of FeCoNiCuZn-based high-entropy alloy (HEA) catalysts, and their surface dynamics during nitrobenzene hydrogenation

Victor Márquez, Janaina S. Santos, Josephus G. Buijnsters, Supareak Praserthdam, Piyasan Praserthdam*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

High-entropy alloys (HEAs) have rapidly become one of the hottest research topics in several fields, including materials science, corrosion technology, and catalysis because of their multiple advantages and their potential applications. In this study, using a novel straightforward electroless deposition method, multi-elemental alloys (FeCoNiCuZn) supported on graphite were prepared with controlled metal loading (HEA/g-X; X = 40, 80, 100) without any high temperature post-treatments. These materials were characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, and showed a composition ranging from 11 at.% to 31 at.% for each metallic element, a total metal loading varying from 1.3 to 5.2 at.% (5.9 to 21.5 wt.%), homogeneous distribution, and an amorphous structure. Electrochemical impedance spectroscopy, cyclic voltammetry, linear sweep voltammetry, and chronoamperometry were used to evaluate the surface dynamics and the effect of the solution pH during the electrochemical hydrogenation of nitrobenzene using the HEA/g-40 material. The nitrobenzene conversion (>9 mmolNB gcat-1 h−1) and aniline production (≈ 4 mmolAN gcat-1 h−1) rates in Na2SO4 solution (at −1.0 V vs. Ag/AgCl) demonstrated a strong dependence on the applied potential. After comparing the results in alkaline medium (KOH), a competitive adsorption of species (nitrobenzene and H2O) was observed, showing a synergistic effect that greatly improved the selectivity of the nitrobenzene hydrogenation to aniline, from 23% in Na2SO4 to an outstanding 94% in KOH at the same applied potential, surpassing the results of a platinum electrode (34% in KOH). These results provide insightful information regarding the nature of the active sites involved in each step of the reaction mechanism, and gives useful means to develop new, tailored multifunctional HEA electrocatalyst materials.

Original languageEnglish
Article number139972
Number of pages15
JournalElectrochimica Acta
Volume410
DOIs
Publication statusPublished - 2022

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Electrocatalysis
  • High-entropy alloys
  • Multiple active sites
  • Nitrobenzene hydrogenation

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