Corrosion Strategy‐Induced Undercoordinated Fe Active Sites in NiFe LDH for Alkaline Water Oxidation

Abstract

The electrochemical restructuring of nickel‐iron layered double hydroxide (NiFe LDH) into high‐oxidation‐state Ni/Fe oxyhydroxide is crucial for the alkaline oxygen evolution reaction (OER). Nevertheless, the sluggish self‐reconstruction kinetics including high energy barriers and complex phase‐transition dynamics of NiFe LDH significantly restrict its electrocatalytic performances. Herein, an oxygen vacancy‐rich NiFe LDH decorated on iron foam (FF) is synthesized through a corrosion strategy. The corrosion process provides undercoordinated active sites in NiFe LDH/FF for OER. In alkaline electrolytes, NiFe LDH/FF displays an exceptional OER activity (a mere 254 mV overpotential with a Tafel slope of 51.7 mV dec−1) and a remarkable stability over 100 h at 500 mA cm−2. Comprehensive experimental and theoretical calculations further reveal that NiFe LDH/FF with undercoordinated active sites facilitates electrochemical reconstruction into highly active NiOOH and FeOOH phases against NiFe LDH/nickel foam. The Fe active sites in NiFe LDH/FF can effectively reduce the adsorption strength of oxygen intermediates, thereby altering the rate‐determining step from (O* → OOH*) to (OH*→ O*) and lowering its reaction energy barrier during the OER process. This work presents an innovative strategy for designing low‐energy‐consumption OER electrocatalysts through a corrosion strategy and defect engineering.