Ultralow Fe instigated defect engineering of hierarchical N–Porous carbon for highly efficient electrocatalysis

•Ultralow iron doping of nitrogen-doped carbon enables high catalytic activity and durability toward oxygen evolution and hydrogen evolution reactions.•Density functional theory study shows that the defects generated by doping are beneficial to oxygen intermediates adsorption–desorption process of OER.•Iron–nitrogen-doped carbon catalyst reveals enhanced OER performance with an overpotential of 248 mV at 10 mA cm−2 and a Tafel value of 85 mV dec−1.