Dual role of Fe boost lattice oxygen oxidation of Mo-based materials from kinetics and thermodynamics

摘要

High-valent Mo-based oxides are easily dissolved in alkaline electrolyte resulting in complete surface reconstruction of catalyst. Therefore, there are few researches on the oxygen evolution reaction (OER) process of this material, especially the reaction mechanism. Herein, Fe-Mo2C@CN was synthesized by introducing 3d metal Fe into the Mo-based catalyst, which inhibited the complete dissolution of Mo. The overpotential is only 226 mV at a current density of 10 mA cm-2. Experimental and density functional theory (DFT) results demonstrate that excellent electrocatalytic performance derives from the dual role of Fe and the thermodynamically favorable single-site lattice oxygen oxidation mechanism (LOM). Electronic-rich pure Fe inhibits the molybdenum dissolution while enhancing the reaction kinetics. And the doped Fe decreases the d-band center, weakens the M-O (metal-oxygen) bond, and promotes the involvement of lattice oxygen in the OER process. This work provides theoretical basis for the engagement of Mo-based catalysts in water splitting.

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