Activating Lattice Oxygen in Spinel ZnCo2O4 through Filling the Oxygen Vacancies with Fluorine for Electrocatalytic Oxygen Evolution.

Abstract

The development of productive catalysts for oxygen evolution reaction (OER) remains a major challenge that requires significant progress in both mechanism and material design. Conventionally, the thermodynamic barrier of the lattice oxidation mechanism (LOM) is lower than that of absorbate evolution mechanism (AEM) because the former could bypass certain limitations. However, it remains a challenging task to control the OER pathway from the AEM to the LOM by taking advantage of the intrinsic properties of catalyst. Herein, we incorporate F anion into oxygen vacancies of spinel ZnCo2O4 and establish the link between electronic structure and the OER catalytic mechanism. Density theoretical calculation reveals that F upshifts O 2p center and activate the redox capability of the lattice O, successfully triggering the LOM pathway, achieving a low overpotential of 350 mV at 10 mA cm-2. Moreover, the large electronegativity of F anion is favorable for the balance of residual protonation, which can stabilize the structure and locally trigger LOM without surface reconstruction during OER reaction. This finding provides a feasible strategy to concurrently enhance the activity and stability of OER, and demonstrates the significance of considering lattice oxygen participation for understanding the OER trend of highly active spinel.