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 NiFe2O4 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 NiFe2O4 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 NiFe2O4-xSex/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. (C) 2021, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.