The development of multi-component bi-functional electrocatalysts is necessary for commercialization of high-performance zinc-air batteries. Herein, foamed carbon-supported nickel-iron oxides interspersed with bamboo-like carbon nanotubes are prepared as bi-functional electrocatalysts for this battery type. During high temperature synthesis, edges of carbon sheets comprising the foamed carbon structure become involuted to form short carbon nanotubes. The composite of carbon nanotubes and network carbon confer high specific surface area and high electrical conductivity on the newly prepared materials. The supported NiFe2 O4 phase improves the oxygen reduction reaction (ORR) activity by fixing more N atoms, and high-valent Ni oxide (Ni2 O3 ) promotes the formation of OO bonds, which is conducive to the oxygen evolution reaction (OER). The optimized material exhibits excellent bi-functional electrocatalytic activity toward both ORR and OER, and its use in the assembled zinc-air battery cell results in a high power density of 150 mW cm-2 with long discharge stability.
Keywords: NiFe 2O 4 phase; foamed carbon; high-performance zinc-air batteries; high-valent Ni oxide; short carbon nanotubes.
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