Electrospinning Synthesis of Bimetallic Nickel-Iron Oxide/Carbon Composite Nanofibers for Efficient Water Oxidation Electrocatalysis

The development of earth-abundant water oxidation electrocatalysts with high activity and durability is very important for many renewable energy conversion/storage processes. Herein, we report a facile synthetic method for the preparation of amorphous nickel-iron oxide/carbon composite nanofibers with high electrocatalytic activity and stability for the oxygen evolution reaction (OER). This method involves two main steps: (i)the electrospinning synthesis of Ni- and Fe-embedded polyvinylpyrrolidone (PVP) polymer nanofibers as the precursor and (ii)the thermal conversion of this precursor in air at 250 degrees C into nickel-iron oxide/carbon composite nanofibers. Moreover, we show that the as-obtained composite material exhibits a comparable catalytic activity and a superior catalytic stability to IrOx/C and RuOx, which are state-of-the-art noble-metal-based water oxidation electrocatalysts. In particular, the obtained amorphous nickel-iron oxide/carbon composite nanofibers with an optimal Ni/Fe molar ratio of 1:2 afford a small overpotential of 310mV at a current density of 10mAcm(-2), show high catalytic stability for >15h, and give >90% Faradaic yield toward the OER. The efficient catalytic activity of the material can be attributed to its overall conducive structural features for the OER, mainly including the amorphous phase structure of nickel-iron oxide, tunable Ni/Fe atomic ratio, and strongly coupled interaction between nickel-iron oxide and nanocarbon.