Constructing Amorphous–Crystalline Interfaces of Nickel–Iron Phosphides/Oxides for Oxygen Evolution Reaction

Oxygen evolution reaction (OER) is the bottleneck of electrocatalytic water splitting due to its sluggish proton-coupled four-electron-transfer kinetics. Interface engineering has been regarded as an effective strategy to promote the OER performance of transition-metal oxide (TMO) electrocatalysts. In this study, we successfully construct the amorphous–crystalline interfaces of NiFePx/NiFeOx nanosheets with substantial oxygen vacancies through controllable surface phosphorization. Experimental results confirm that the unique structure possesses fast charge transfer, abundant active sites, and enhanced intrinsic activity, resulting in the outstanding OER performance. The optimized NiFePx/NiFeOx displays a low overpotential of 238 mV at 20 mA cm–2 and excellent stability in 1 M KOH electrolyte. This study provides an effective strategy to promote the OER performance of TMOs in alkaline water splitting.