Synergistic Coupling of Anionic Ligands To Optimize the Electronic and Catalytic Properties of Metal–Organic Framework-Converted Oxygen-Evolving Catalysts

Abstract

Multimetallic oxygen evolution reaction (OER) electrocatalysts have recently gained significant attention due to their excellent intrinsic activity resulting from the synergistic interplay between multiple metal sites. However, in these multimetallic catalyst systems, the function of their bridging anionic ligands (e.g., O2–, S2–, and P3–/PO43–) is rarely investigated, partially due to the lack of an ideal material model system. Herein, by combining a careful electrochemical conversion of metal–organic framework (MOF) precursors with low-temperature phosphorization processes, we designed a series of NiFe-based model catalysts as a proof-of-concept platform to identify the roles of different anionic ligands in tuning the redox and electronic properties of metal sites. Our experimental and theoretical results reveal that ligands having varying electron-withdrawing/-donating ability can modulate not only the electron density of Ni2+/Fe3+ centers but also the electron transfer efficiency from Ni2+ to neighbor...