Resumen:
"Although clean energy generation utilizing the Oxygen Reduction Reaction (ORR) can
be considered a promising strategy, this approach remains challenging by the dependence on high
loadings of noble metals, mainly Platinum (Pt). Therefore, efforts have been directed to develop
new and efficient electrocatalysts that could decrease the Pt content (e.g., by nanotechnology tools or
alloying) or replace them completely in these systems. The present investigation shows that high
catalytic activity can be reached towards the ORR by employing 1.8 ± 0.7 nm Ir nanoparticles (NPs)
deposited onto MnO2 nanowires surface under low Ir loadings (1.2 wt.%). Interestingly, we observed
that the MnO2
-Ir nanohybrid presented high catalytic activity for the ORR close to commercial
Pt/C (20.0 wt.% of Pt), indicating that it could obtain efficient performance using a simple synthetic
procedure. The MnO2
-Ir electrocatalyst also showed improved stability relative to commercial Pt/C,
in which only a slight activity loss was observed after 50 reaction cycles. Considering our findings,
the superior performance delivered by the MnO2
-Ir nanohybrid may be related to (i) the significant
concentration of reduced Mn3+ species, leading to increased concentration of oxygen vacancies at its
surface; (ii) the presence of strong metal-support interactions (SMSI), in which the electronic effect
between MnOx and Ir may enhance the ORR process; and (iii) the unique structure comprised by Ir
ultrasmall sizes at the nanowire surface that enable the exposure of high energy surface/facets, high
surface-to-volume ratios, and their uniform dispersion."
