MOF-Derived Iron-Cobalt Bimetallic Selenides for Water Electrolysis with High-Efficiency Oxygen Evolution Reaction

Highly active and stable oxygen evolution reaction (OER) electrocatalysts for water electrolysis are currently in high demand. Herein, a rationally designed three-dimensional (3D) CoFe selenide porous array (Fe-CoSe PA) is synthesized through ion exchange from zeolitic imidazolate framework-L (ZIF-L) nanoarray, followed by a facile selenization under hydrothermal conditions for OER electrocatalysis. During the OER process, the surface of Fe-CoSe PA is rapidly oxidized to CoFe oxides/hydroxides, which prevents the inner layer from being oxidized. Benefiting from the high porosity, abundant active sites, and the high conductivity of inner Fe-CoSe, Fe-CoSe PA exhibits excellent OER performance, with an overpotential of 285 mV at a current density of 10 mA cm^-2, and a small Tafel slope of 68 mV dec^-1, as well as high stability under 50 h of continuous testing. The present work could provide a facile route for fabricating 3D porous selenides for highly efficient OER catalysis.