Nickel Nitrate Hydroxide Holey Nanosheets for Efficient Oxygen Evolution Electrocatalysis in Alkaline Condition

Herein, vertically aligned nickel nitrate hydroxide (NiNH) holey nanosheet arrays are controllably in situ grown on nickel foam (NF) via a facile one-step solvothermal method. Unique architecture constructed with two-dimensional (2D) holey nanosheets provides high exposure of active sites and benefits mass transport of electrolyte, which is favorable for OER electrocatalysis. Holey structure maintains through the structural conversion from NiNH to γ-NiOOH during OER activation. The vertically aligned γ-NiOOH porous nanosheet arrays exhibit tight adhesion on NF and sufficient Ni 2+ /Ni 3+ redox species, which guarantee OER activity and durable stability. Optimal OER activity with overpotential of 231 mV at 50 mA/cm 2 , a Tafel slope of 123 mV/dec and a good stability can be achieved in 1 M KOH solution, which is superior to most previous reported transition metal-based electrocatalysts. Our work can provide a facile strategy to obtain highly efficient holey OER electrocatalysts. Graphic Abstract