Hierarchical Fe–Co LDH/Fe-CoSOH Nanoneedle-Nanosheet Heterostructure for Efficient Oxygen Evolution

Abstract

Developing efficient and stable oxygen evolution reaction catalysts is crucial for practical water splitting. Herein, a mild room-temperature sulfidation strategy is employed to construct a hierarchical heterostructure composed of Fe-Co LDH nanoneedles and ultrathin Fe-CoSOH nanosheets on nickel foam. This nanoneedle-nanosheet architecture provides abundant active sites, optimized charge transfer pathways, and enhanced electrolyte wettability. Electrochemical tests show that the resulting catalyst exhibits excellent OER activity in 1.0 M KOH, requiring an overpotential of 230 mV to achieve a current density of 10 mA cm^–2, with a Tafel slope of 35.37 mV dec^–1. Notably, it maintains stable operation for over 600 h at a current density of 100 mA cm^–2. Mechanism studies reveal that sulfur doping optimizes the electronic structure and promotes the reconstruction into the active CoOOH phase at a lower potential. Finite element simulations confirm that the hierarchical structure enhances the local electric field and reactant transport. This work provides an effective strategy for synergistically improving electrocatalytic performance through anion engineering and structural design.