Nanowires-based MnO2-Ru/rGO: An efficient oxygen reduction reaction electrocatalyst

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Applied Surface Science
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Machado Ferreira R.
Lalesca Santos de Lima S.
dos Santos Pereira F.
Nagib Mouchrek C.
Atsushi Takana A.
Humberto Domingues S.
Eliza Silva Fonsaca J.
Liu L.
Yatsuzuka R.
Gabriel Marques da Silva A.
de Medeiros Aquino F.
Aurelio Suller Garcia M.
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© 2023Oxygen Reduction Reaction (ORR) for clean energy is hindered by expensive Pt-based electrocatalysts, prompting efforts to replace it with alternative electrocatalysts. Thus, we started by synthesizing MnO2 nanowires through a hydrothermal approach, followed by the growth of ruthenium nanoparticles (Ru NPs) without surface modification, using just 2.0 wt% of the noble metal (MnO2-Ru). However, to further enhance the electrocatalyst's performance and reduce costs, we combined different ratios of reduced graphene oxide (rGO) with the electrocatalyst. X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy were employed to characterize the chemical composition and morphological properties of MnO2-Ru. These analyses identified the presence of the compounds during synthesis and confirmed the deposition of Ru NPs on the surface of MnO2 nanowires. The optimized MnO2-Ru/rGO demonstrated superior ORR activity than rGO, MnO2, and MnO2-Ru individually, with more positive onset potential (−0.054 V) and half-wave potential of −0.173 V. Notably, MnO2-Ru/rGO reduced oxygen via the four-electron transfer pathway. Furthermore, the higher stability and excellent methanol tolerance of MnO2-Ru/rGO compared to the commercial 20 wt% Pt/C indicates its suitability for fuel cells, maintaining approximately 70 % of its initial current after 8000 s.
Assuntos Scopus
Clean energy , Methanol tolerance , MnO2 nanowire , Oxygen reduction reaction , Performance costs , Pt-based electrocatalyst , Reduced graphene oxides , Ru nanoparticles , Ruthenium Nanoparticles , Surface-modification
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