Metal-organic framework interface engineering for highly efficient oxygen evolution reaction.

Metal-organic frameworks (MOFs) with intrinsically porous structures and well-dispersed metal sites are promising candidates for the oxygen evolution reaction (OER). However, the practical applications of MOFs for OER are significantly constrained due to their poor charge transfer property and insufficient inherent activity. Herein, we utilized caffeic acid as a bridging agent to covalently bond FeNi-MOF with NiMoO4 in order to tune the charge transfer properties for efficient OER. The optimized organic-inorganic heterocatalyst demonstrates superior OER performance with a low overpotential of 256 mV at a current density of 10 mA cm-2 and long-term stability, outperforming the benchmark IrO2 catalyst and single counterparts. Both experimental and theoretical results indicate that electrons can be transferred from FeNi-MOF to NiMoO4 via a caffeic acid bridging agent, which improves not only the electrical conductivity but also the adsorption capacity of OH- intermediates on MOFs. Therefore, the enhanced OER activity of the heterocatalyst is attributed to the synergistic effects of the multi-components. This study paves the way for the rational design of MOFs-based heterostructures towards efficient electrocatalytic oxygen evolution.