Facile Room-Temperature Synthesis of Porous Sulfur-Doped NiFe-LDH Nanosheet Arrays for Efficient Oxygen Evolution

The multielectron nature of the oxygen evolution reaction (OER) imposes severe kinetic constraints on water splitting efficiency. NiFe-layered double hydroxides (NiFe-LDHs) are promising OER catalysts but suffer from few active sites and low conductivity. We developed self-supported porous nanosheet arrays of sulfur-doped NiFe-layered double hydroxide (S-NiFe-LDH/NF) via a facile room-temperature electrodeposition-corrosion method. Sulfur doping creates porous structures and oxygen vacancies that expose active sites and enhance conductivity while tuning the electronic configuration of Ni/Fe active centers to reduce the activation barrier of the *O → *OOH step. Additionally, sulfur doping accelerates the γ-NiOOH formation kinetics. In 1.0 M KOH, S-NiFe-LDH/NF requires only 159 and 235 mV to drive 10 and 100 mA·cm–2, respectively. The corresponding Tafel slope is 26.3 mV·dec–1, surpassing those of both NiFe-LDH/NF and commercial RuO2. Coupled with a Ni3S2/Ni/NF cathode exhibiting a 61 mV HER overpotential at 10 mA·cm–2, the integrated electrolyzer delivers 10 and 100 mA·cm–2 at 1.45 and 1.61 V, respectively, and sustains 1000 mA·cm–2 at 1.94 V for 200 h. This study presents a scalable and economical approach for designing efficient electrocatalysts for industrial-scale water splitting.