Leaching-Reconstruction Engineering of Anions on Ferronickel Phosphate Promotes the Enhancement of the Oxygen Evolution Reaction

Electrochemical reconstruction typically generates powerful active sites for the oxygen evolution reaction (OER). However, engineering effective reconstruction strategies to manipulate the in situ formation of desired catalytically active surfaces, generate powerful active sites, and enhance their catalytic performance remains a challenge. Herein, leveraging the oxidation-potential-assisted precipitation etching, a heterostructure of NiFeOOH/NiFe phosphate was meticulously engineered to achieve highly efficient OER. During the electrochemical reconstruction, the leaching of inactive PO₄^3- species in NiFe phosphate facilitates the exposure of more Ni and/or Fe species and creates more pores, thereby contributing to the formation of a NiFeOOH layer on the surface of NiFe phosphate. The resultant NiFeOOH/NiFe phosphate exhibits excellent OER activity with an overpotential of 205 mV at 50 mA cm^-2 in an alkaline electrolyte. The theoretical calculations reveal that the heterostructure of NiFeOOH/NiFe phosphate weakens the thermodynamic barrier from *O to *OOH, thus enhancing the OER activity. The present proof-of-concept study introduces a leaching engineering approach to facilitate further exploration and development of highly efficient energy-related applications.