MOF-derived M-OOH with rich oxygen defects by in situ electro-oxidation reconstitution for a highly efficient oxygen evolution reaction

Abstract

The oxygen evolution reaction (OER) is an important half-reaction in the field of energy production. However, effective, simple, and green preparation of low-cost OER electrocatalysts remains a problem. Herein, a novel in situ electro-oxidation reconstitution strategy is first adopted to derive metal-oxyhydroxides with rich oxygen-defects (M-OOHv) on the surface of Fe₂Co-MOF with nickel foam (NF) as the substrate, named Fe₂Co-MOF@M-OOHv-ER/NF, which exhibits an extremely low overpotential of 224 mV at a current density of 10 mA cm⁻² in 1 M KOH for the OER, with a small Tafel slope of 44.87 mV dec⁻¹ and a high electrochemically active surface area of 50.5 cm². The in situ Raman reveals the transition of the MOF phase to the M-OOHv phase, which is the real active site for the OER. Furthermore, X-ray photoelectron spectroscopy, photoluminescence, and density functional theory calculations prove that the bimetal synergistic effect and the oxygen defects in the M-OOHv, regulating the electron density of states, are the real reasons for the higher catalytic activity for the OER. In short, the newly prepared Fe₂Co-MOF@M-OOHv-ER/NF not only can be prepared by an efficient, simple, and green strategy, but also has excellent oxygen evolution performance.