Precise Anchoring of Fe Sites by Regulating Crystallinity of Novel Binuclear Ni-MOF for Revealing Mechanism of Electrocatalytic Oxygen Evolution.

ABSTRACT

Bimetallic metal-organic framework (BMOF) exhibits better electrocatalytic performance than mono-MOF, but deciphering the precise anchoring of foreign atoms and revealing the underlying mechanisms at the atomic level remains a major challenge. Herein, a novel binuclear NiFe-MOF with precise anchoring of Fe sites is synthesized. The low-crystallinity (LC)-NiFe0.33 -MOF exhibited abundant unsaturated active sites and demonstrated excellent electrocatalytic oxygen evolution reaction (OER) performance. It achieved an ultralow overpotential of 230 mV at 10 mA cm-2 and a Tafel slope of 41 mV dec-1 . Using a combination of modulating crystallinity, X-ray absorption spectroscopy, and theoretical calculations, the accurate metal sequence of BMOF and the synergistic effect of the active sites are identified, revealing that the adjacent active site plays a significant role in regulating the catalytic performance of the endmost active site. The proposed model of BMOF electrocatalysts facilitates the investigation of efficient OER electrocatalysts and the related catalytic mechanisms.