Fe3O4 nano-octahedra and SnO2 nanorods modifying low-Pd amount electrocatalysts for alkaline direct ethanol fuel cells

Gentil TC, Lucchetti LE, Moura JPC, Silva JCM, Minichová M, Briega-Martos V, Trench AB, Batista BL, Cherevko S, Santos MC (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Electrochimica Acta Elsevier

Book Volume: 535

Article Number: 146576

DOI: 10.1016/j.electacta.2025.146576

Abstract

This work describes the ethanol oxidation reaction (EOR) in alkaline medium using low-palladium nanoparticle electrocatalysts modified by Fe3O4 nano-octahedra and SnO2 nanorods. Operation studies on an alkaline direct ethanol fuel cell (ADEFC) were conducted using the developed electrocatalysts, and stability studies were performed using the advanced scanning flow cell (SFC) technique combined to inductively coupled plasma mass spectrometry (online SFC-ICP-MS). The EOR was catalyzed by single (Pd/C and commercial Pd/C Alfa Aesar) and by synthesized binary/ternary electrocatalysts, in which Fe₃O₄ and SnO₂ nanostructures partially replaced the high-cost noble metal. The PdFe₃O₄/C was identified as the most promising synthesized material in the electrochemical studies, exhibiting the highest mass activity (1426 mA mg⁻¹ Pd) by cyclic voltammetry (CV), followed by the binary PdSnO2/C (1135 mA mg⁻¹ Pd), and by the ternary (1074 mA mg⁻¹ Pd). This enhancement was attributed to the bifunctional mechanism enabled by Fe₃O₄ and SnO₂, therefore reducing poisoning and improving the EOR. Moreover, the operating results revealed that PdFe₃O₄/C showed the highest power density among the synthesized materials (31 mW cm⁻² at 70 °C), even with a ∼45 % reduction in Pd content compared to the commercial. The XPS results showed that the Pd 3d₅/₂ and 3d₃/₂ peaks for PdFe₃O₄/C, PdSnO₂/C, and PdFe₃O₄SnO₂/C were shifted by ∼0.5 eV to higher binding energies compared to Pd/C, indicating a loss of electron density in Pd due to strong metal–oxide interactions. These interactions led to a downward shift in the D-band center of Pd, weakening the Pd-adsorbed bonds, facilitating the desorption of intermediates, and improving the catalyst tolerance to toxic species. Furthermore, the higher proportion of Pd oxides in the binary and ternary materials appeared to contribute to the supply of oxygenated species required for the oxidation of EOR intermediates. Thus, the observed enhancement resulted from synergistic bifunctional and electronic effects. Finally, online SFC-ICP-MS studies showed that Fe3O4 nano-octahedra contributed to the enhanced stability of the electrocatalyst, as PdFe₃O₄/C exhibited less Pd dissolution and no Fe dissolution.

Authors with CRIS profile

Mária Minichová Lehrstuhl für Elektrokatalyse (HIERN) Serhiy Cherevko Lehrstuhl für Elektrokatalyse (HIERN)

Involved external institutions

Universidade Federal do ABC (UFABC) / Federal University of ABC BR Brazil (BR) Fluminense Federal University / Universidade Federal Fluminense (UFF) BR Brazil (BR) Forschungszentrum Jülich / Research Centre Jülich (FZJ) DE Germany (DE)

How to cite

APA:

Gentil, T.C., Lucchetti, L.E., Moura, J.P.C., Silva, J.C.M., Minichová, M., Briega-Martos, V.,... Santos, M.C. (2025). Fe3O4 nano-octahedra and SnO2 nanorods modifying low-Pd amount electrocatalysts for alkaline direct ethanol fuel cells. Electrochimica Acta, 535. https://doi.org/10.1016/j.electacta.2025.146576

MLA:

Gentil, Tuani C., et al. "Fe3O4 nano-octahedra and SnO2 nanorods modifying low-Pd amount electrocatalysts for alkaline direct ethanol fuel cells." Electrochimica Acta 535 (2025).

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