Comunicazione
Electrospun spinel-structured high-entropy oxide nanofibers as electrocatalysts for oxygen evolution in alkaline medium.
Santangelo S., Triolo C., Schweidler S., Lin L., Pagot G., Di Noto V., Breitung B.
Water electrolysis powered by renewable sources is the greenest way to produce $H_2$, a promising energy vector that could help bring the World to net zero emissions in the coming decades. However, the slow kinetics of the oxygen evolution reaction (OER) represents a limitation for its broad market penetration. Spinel transition metal oxides have shown great potential as a sustainable alternative to precious metal-based electrocatalysts. In this communication, electrospun spinel high-entropy (Cr, Mn, Fe, Co, Ni), (Cr, Mn, Fe, Co, Zn) and (Cr, Mn, Fe, Ni, Zn) oxide nanofibers (NFs) are evaluated as OER electrocatalysts in 1 M KOH solution.($Cr_{0.2}Mn_{0.2}Fe_{0.2}Co_{0.2}Ni_{0.2})_{3}O_{4}$ NFs outperform not only $(Cr_{0.2}Mn_{0.2}Fe_{0.2}Co_{0.2}Zn_{0.2})_{3}O_{4}$ and $(Cr_{0.2}Mn_{0.2}Fe_{0.2}Ni_{0.2}Zn_{0.2})_{3}O_{4}$ NFs, but also $IrO_{2}$ reference electrocatalyst (Tafel slopes: 49.1, 62.5, 59.6 and 52.9 mV/dec, respectively). The higher concentration of oxygen vacancies on their surface and the higher occupation of octahedral sites by redox-active $Co^{2+}$ and $Ni^{2+}$ centres are responsible for their behaviour.