Real Active Site Identification of Co/Co 3 O 4 Anchoring Ni-MOF Nanosheets with Fast OER Kinetics for Overall Water Splitting.

Doping metals and constructing heterostructures are pivotal strategies to enhance the electrocatalytic activity of metal-organic frameworks (MOFs). Nevertheless, effectively designing MOF-based catalysts that incorporate both doping and multiphase interfaces poses a significant challenge. In this study, a one-step Co-doped and Co ₃ O ₄ -modified Ni-MOF catalyst (named Ni NDC-Co/CP) with a thickness of approximately 5.0 nm was synthesized by a solvothermal-assisted etching growth strategy. Studies indicate that the formation of the Co-O-Ni-O-Co bond in Ni NDC-Co/CP was found to facilitate charge density redistribution more effectively than the Co-O-Ni bimetallic synergistic effect in NiCo NDC/CP. The designating Ni NDC-Co/CP achieved superior oxygen evolution reaction (OER) activity (245 mV @ 10 mA cm ^-2 ) and robust long stability (100 h @ 100 mA cm ^-2 ) in 1.0 M KOH. Furthermore, the Ni NDC-Co/CP ⁽⁺⁾ ||Pt/C/CP ^(-) displays pregnant overall water splitting performance, achieving a current density of 10 mA cm ^-2 at an ultralow voltage of 1.52 V, which is significantly lower than that of commercial electrolyzer using Pt/C and IrO ₂ electrode materials. In situ Raman spectroscopy elucidated the transformation of Ni NDC-Co to Ni(Co)OOH under an electric field. This study introduces a novel approach for the rational design of MOF-based OER electrocatalysts.