Bifunctional Mesoporous MO x (M = Cr, Fe, Co, Ni, Ce) Oxygen Electrocatalysts for Platinum Group Metal-Free Oxygen Pumps

• Bifunctional electrocatalysts with both accelerated oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) enable high-power density electricity storage and decentralized extraction of pure oxygen from air for usage in health care. Herein, a hydrothermal synthesis employing the anionic surfactant sodium dodecyl sulfate as structure-directing agent is developed to fabricate a family of crystalline mesoporous metal oxides (meso-MO X , M = Cr, Fe, Co, Ni, Ce). The pore size and specific surface area depend on the metal used and they range from 3 to 6 nm and 60 to 200 m(2) g(-1), respectively. NiO and Co3O4 show a higher catalytic efficiency in alkaline media in comparison with the other oxides studied, and their activities are comparable with the values reported for platinum group metal (PGM)-based electrocatalysts. This stems from lower voltage losses and by the presence of specific hydroxide adsorbates on the surface. Both ORR and OER driven on Co3O4 show the unified rate-determining chemical step (|OO-|(center dot) (ads) + H2O <-> |OOH|(center dot) (ads) + OH-, where | X | ads are the species adsorbed on active sites). The bifunctional ORR/OER electrocatalysis obtained on mesoporous NiO is utilized for the first symmetrical PGM-free oxygen pump fed by air and water only.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

mesoporous metal oxides; oxygen evolution reaction; oxygen pumps; oxygen reduction reaction; soft-templating

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