Accelerating Oxygen Evolution Activity via Premagnetization-Induced Active Sites in Ferromagnetic Nickel-Iron Hydroxide Catalysts.

Abstract

Magnetization induced by an external magnetic field has emerged as a potential strategy to enhance the catalytic performance of the oxygen evolution reaction (OER). However, the underlying mechanism, particularly its impact on surface adsorbates, reaction intermediates, and surface reconfiguration, remains unclear. Here we delve into the adsorbate evolution mechanism during the OER catalyzed by ferromagnetic NiFe-hydroxide (LDH-FeOOH) after temporary exposure to a magnetic field (premagnetization, PM). The heterojunction induces crucial interfacial electronic modulation, specifically altering the electronic structure and Ni-O bonding configuration of interfacial Ni sites in the LDH phase, which potentially enhances the magnetic field sensitivity of Ni sites during the premagnetization processes. Following PM treatment, the Tafel slope of LDH-FeOOH significantly decreases from 111.7 to 44.6 mV/dec, indicating the enhancement of catalytic activity. Our investigation reveals that PM improved deprotonation ability induces surface reconstruction, forming highly active high-valenced nickle (oxy)-hydroxide that serves as more possible active sites. Additionally, the PM process promotes to establish a spin conduction channel that optimizes the adsorption energy of key intermediates and enhances spin-oriented electron transfer processes. Furthermore, enhancement of OER kinetics via PM treatment has been validated with both laboratory-scale anion-exchange membrane (AME) eletrcolyzer and industrial-scale commercial alkaline water electrolyzer. This study not only offers new insights into the role of PM in catalyst performance but also highlights its substantial potential for industrial hydrogen production applications.