Regulating the electronic structure and spin state of iron-based metal-organic frameworks for efficient oxygen evolution electrocatalysis

Iron-based metal-organic frameworks (MOFs) have been applied for oxygen evolution reaction (OER) due to their unique physicochemical properties. The relatively poor activity and conductivity limit the further development and use of iron-based MOFs. Here, regulating the electronic structure and the spin state through ion-induced skeleton reconstruction method to improve the catalytic performance is developed. The experimental and DFT calculation show that the introduction of indium ions promotes the iron active site from low spin state to high spin state, and the d-band center of the catalyst is significantly improved, which can enhance the oxygen adsorption and the conductivity of the catalyst to improve the OER performance. The MIL-88b-Fe_0.950In_0.050 shows the best catalytic performance, with an overpotential of only 243 mV at a current density of 100 mA cm⁻². The catalytic activity of the catalyst remains undecayed after 110 h of continuous use.