Simple solution route to synthesize NiFe oxide/nanocarbon composite catalysts for the oxygen evolution reaction

Abstract

Water electrolysis is a promising technology for the mass production of green hydrogen. However, the oxygen evolution reaction (OER), which is a half-reaction of water electrolysis, is kinetically sluggish, and many active earth-abundant OER catalysts have been investigated. In this study, we prepared a NiFe oxide/nanocarbon composite using a simple solution process. An ethanol solution of Ni nitrate and Fe nitrate was added to commercial carbon black, and the mixture was calcined in air at 350 °C. During this simple process, amorphous NiFe oxide was deposited onto the carbon black. Energy-dispersive X-ray spectroscopy indicated that the Ni and Fe were well dispersed on the carbon black. X-ray photoelectron spectroscopy and cyclic voltammetry indicated that Ni and Fe were located adjacent to each other, and that the NiFe species had formed. The NiFe oxide/nanocarbon composite catalysts exhibited high OER activity that was comparable to that of state-of-the-art Ir/C catalysts. This study demonstrated that the simple solution process produced a NiFe oxide/nanocarbon composite catalyst that efficiently catalyzes the OER. This process could be used to synthesize active and cost-effective OER catalysts for the production of green hydrogen.