Vanadium Nitride/Carbon Nanotube Vertical Nanoarrays on Iron Foam for Oxygen Evolution Reaction

Exploring earth-abundant electrocatalysts with high efficiency and stability for oxygen evolution reaction (OER) is vital to hydrogen production technology, which especially can work well at higher current density. Herein, we report a facile method for the in situ growth of vertical nanoarray vanadium nitride and carbon nanotube hybrid materials on iron foam (labeled as VN/CNT/IF). The obtained catalyst exhibits good electrocatalytic activity and stability toward OER in alkaline media, with a low overpotential of 270 mV at 10 mA cm–2 and a small Tafel slope of 60 mV dec–1. Meanwhile, the obtained materials can deliver a large current density of 1000 mA cm–2 at an overpotential of only 410 mV for OER in 30 wt % KOH, an electrolyte widely used in commercial aqueous alkaline electrolyzers. The experimental results indicate that the vertical nanoarray structure offers a high specific surface area and exposes abundant active sites. In addition, the vanadium nitride and carbon nanotube hybrid can strongly decrease the charge transfer resistance, further facilitating the water-splitting reaction kinetics.