Porous Ni–Fe–Cr electrocatalyst for the oxygen and hydrogen evolution reaction via facile one-step electrodeposition

A high-performance bifunctional Ni–Fe–Cr electrocatalyst with a coral reef-like porous structure was fabricated by facile one-step electrodeposition at a high cathodic current density of 8 A/cm2 for 30 min in an optimal electrodeposition bath containing 80 g/L CrCl3 and 1 M NH4Cl. The highly porous Ni–Fe–Cr electrocatalyst exhibits extremely low overpotential of 234 mV for oxygen evolution reaction (OER) and 13 mVRHE for hydrogen evolution reaction (HER) in 1 M KOH at a current density of 10 mA/cm2, respectively. The excellent performance of the Ni–Fe–Cr electrocatalyst can be attributed to the modulation of the electronic structure due to the incorporation of Cr enhanced performance capabilities of the porous Ni–Fe–Cr originate from the increased electrochemical active surface area (ECSA), which is 22 times larger than that of thin Ni–Fe–Cr. Moreover, the catalyst exhibits high stability towards the OER and HER in an alkaline solution for 36 h. This work offers a facile synthesis method by which to create a highly porous Ni–Fe–Cr electrocatalyst by electrodeposition and a strategy for increasing the catalytic activity by controlling the pore size.