Selective Se doping of NiFe2O4 on an active NiOOH scaffold for efficient and robust water oxidation

There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction (OER) while maintaining their robustness at large outputs. Herein, an etching-assisted synthesis approach was developed to integrate highly active NiFe 2 O 4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel. A precise selenization strategy was then introduced to achieve selective Se doping of NiFe 2 O 4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution. The resulting NiFe 2 O 4− x Se x /NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm −2 , respectively. More importantly, the catalyst exhibited remarkable durability at a stable current output of 100 mA cm −2 for hundreds of hours. These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials. The rational fabrication of selectively Se-doped NiFe 2 O 4 nanoparticles on active NiOOH nanosheet arrays enables efficient and robust OER electrocatalysts for scalable hydrogen production with commercial stainless steel.