Chemical Transformation Induced Core-Shell NiP@FeP Heterostructures toward Efficient Electrocatalytic Oxygen Evolution.

The oxygen evolution reaction (OER) is a crucial reaction in water splitting, metal-air batteries, and other electrochemical conversion technologies. Rationally designed catalysts with rich active sites and high intrinsic activity have been considered as a hopeful strategy to address the sluggish kinetics for OER. However, constructing such active sites in non-noble catalysts still faces grand challenges. To this end, we fabricate a NiP@FeP core-shell structure with outperforming performance toward OER via chemical transformation of rationally designed Ni-MOF hybrid nanosheets. Specifically, the Ni-MOF nanosheets and their supported Fe-based nanomaterials were in situ transformed into porous NiP@FeP core-shell nanosheets composed of NiP and FeP nanodomains in homogenous dispersion via a phosphorization process. When employed as the OER electrocatalyst, the NiP@FeP core-shell nanosheets exhibits excellent OER performance, with a low overpotential of 238/247 mV to drive 50/100 mA cm, a small Tafel slope of 32.91 mV dec, as well as outstanding durability, which could be mainly ascribed to the strong electronic interaction between NiP and FeP nanodomains stabilizing more Ni and Fe atoms with higher valence. These high-valence metal sites promote the generation of high-active Ni/FeOOH to enhance OER activity.