Iron Quantum Dots Electro-Assembling on Vulcan XC-72R: Hydrogen Peroxide Generation for Space Applications

Abstract

Highly dispersed iron-based quantum dots (QDs) onto powdered Vulcan XC-72R substrate were successfully electrodeposited by the rotating disk slurry electrodeposition (RoDSE) technique. Our findings through chemical physics characterization revealed that the continuous electron pathway interaction between the interface metal-carbon is controlled. The rotating ring-disk electrode (RRDE) and the prototype generation unit (PGU) of <i>in-situ</i> H₂O₂ generation in fuel cell experiments revealed a high activity for the oxygen reduction reaction (ORR) via two-electron pathway. These results establish the Fe/Vulcan catalyst at a competitive level for space and terrestrial new materials carriers, specifically for the <i>in-situ</i> H₂O₂ production. Transmission electron microscopy (TEM) analysis reveals the well-dispersed Fe-based quantum dots with a particle size of 4 nm. The structural and chemical-physical characterization through induced coupled plasma-optical emission spectroscopy (ICP-OES), transmission scanning electron microscopy (STEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS); reveals that, under atmospheric conditions, our quantum dots system is a Fe^2+/3+/Fe³⁺ combination. The QDs oxidation state tunability was showed by the applied potential. The obtention of H₂O₂ under the compatibility conditions of the drinking water resources available in the International Space Station (ISS) enhances the applicability of this iron- and carbon-based materials for <i>in-situ</i> H₂O₂ production in future space scenarios. Terrestrial and space abundance of iron and carbon, combined with its low toxicity and high stability, consolidates this present work to be further extended for the large-scale production of Fe-based nanoparticles for several applications.