Iridium incorporated cobalt-based hydroxide on nickel-contained carbon nanofibers renders highly efficient oxygen evolution reaction

•Iridium incorporated cobalt-based hydroxide on nickel-doped carbon nanofibers are prepared.•The electrocatalyst shows unique nanofibrous morphology with a core-sheath structure and low crystallinity.•The electrocatalyst presents a low overpotential of 240 mV at 10 mA cm−2 for OER.•The Pt/C||Ni-CNFs/Ir-Co(OH)2 electrolyzer exhibits a cell voltage of 1.50 V to attain 10 mA cm−2.