A Flexible Electrode Based on Al-Doped Nickel Hydroxide Wrapped to Carbon Nanotubes Forest for Efficient Oxygen Evolution

The development of highly active, cheap and stable electrocatalysts for overall water splitting is strategic for industrial electrolysis process aiming at a sustainable hydrogen production. Here, we report the impressive electrocatalytic activity for the oxygen evolution reaction of Al-doped Ni(OH)2 deposited on a chemically-etched carbon nanotubes forest (CNT-F) supported on a flexible polymer/CNTs nanocomposite. Our monolithic electrode generates a stable current density of 10 mA/cm2 at an overpotential (?) of 0.28 V toward the oxygen evolution reaction in NaOH 1 M and reaches approximately 200 mA/cm2 at 1.7 V vs RHE in KOH 6 M. The CNT-F/NiAl electrode shows also an outstanding activity for the hydrogen evolution reaction in alkaline conditions. When CNT-F/NiAl is used both at the anode and at the cathode, our device is able to sustain the overall water splitting reaching 10 mA/cm2 at ? = 1.96 V. The high electrocatalytic activity of the CNT-F/NiAl hydroxide is due to the huge surface area of the CNT forest, to the high electrical conductivity of the nanocomposite substrate, as well as to the interactions between the NiAl catalyst and the CNTs.