Mechanochemical Post-Synthesis of Metal–Organic Framework-Based Pre-Electrocatalysts with Surface FeONi/Co Bonding for Highly Efficient Oxygen Evolution

Abstract

Rational surface engineering of metal–organic frameworks (MOFs) provide potential opportunities to address the sluggish kinetics of oxygen evolution reaction (OER). However, the development of MOF-based materials with low overpotentials remains a great challenge. Herein, a post-synthesis strategy to prepare highly efficient MOF-based pre-electrocatalysts via all-solid-phase mechanochemistry is demonstrated. The surface of a Fe-based MOF (MIL-53) can be reconstructed and anchored with atomically dispersed Ni/Co sites. As expected, the optimized M-NiA-CoN exhibits a very low overpotential of 180 mV at 10 mA cm−2 and a small Tafel slope of 41 mV dec−1 in 1 m KOH electrolyte. The superior electrocatalytic OER activity is mainly due to the formation of surface FeONi/Co bonding. Furthermore, density functional theory calculations reveal that the transformation from *OH to *O is the rate-determining step and the electrocatalytic OER activity trend at different metal sites is Co > Ni≈Fe.