Reconfiguration and activation induced by characteristic migration of transition metal-ions between interfaces of high-entropy oxygen evolution catalysts

Abstract

The tremendous potential of high entropy alloys (HEA) in the electrocatalysis of oxygen evolution reaction (OER) is constantly revealed, but there are still many issues worth discussing how to build more reliable HEA systems to maximize its synergistic advantages and how to explain their complex electrochemical interface behavior. Herein, a convenient composite metal-organic frames (MOFs) co-pyrolysis method is designed to reconstruct the precursor in a high temperature inert atmosphere and prepare a core-shell structure nitrogen-containing carbon nanotube coated six-metals alloys (FeCoNiVCrZn HEA) as an excellent alkaline medium OER catalyst. It can achieve the working current density of 10 mA cm-2 at 249 mV overpotential, and the current fluctuation range is less than 3.12 % after long-time constant voltage operation in 1M KOH electrolyte. The electrocatalytic activity and stability surpass the same type of alloy catalyst and commercial IrO2/C catalyst. We tracked the trend of the concentration and chemical state of metal-ions between two phases during the electrochemical process, and revealed that the interface reconfiguration of the high-entropy alloy is regulated by the characteristic transition metal migration behavior. On this basis, we through the density functional theory (DFT) calculation, further explore in the alkaline medium surface metal dissolution and surface reconfiguration behavior, verify the active MOOH (M = Fe, Co and Ni) phase plays a key role in the reaction steps of adsorption of oxygen species. This work for the study of HEA in OER structure optimization and interface behavior provides a unique perspective, and for the development of advanced OER electrocatalyst shows a new prospect.