Preparation and study of sulfide-based electrocatalysts synthesized from NiFeCr layered triple hydroxide precursor for utilization in water splitting applications.

The development of bifunctional electrocatalysts that demonstrate both high efficiency and robust stability for overall water splitting remains a significant challenge in advancing sustainable hydrogen production. In this study, a NiCrFe-layered double hydroxide (LDH) nanostructure was fabricated on nickel foam and subsequently subjected to partial or complete sulfidation using three different sulfidating agents (Na 2 S, C 2 H 5 NS [thioacetamide], and CH 4 N 2 S [thiourea]). A variety of detailed characterization methods were employed to analyze the catalysts, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Their electrocatalytic performance was then systematically assessed. Among them, NiFeCr-LDH-NF-CH₄N₂S2 (fully sulfidated with CH₄N₂S) exhibited the most remarkable activity, requiring a low overpotential to achieve 10 mA cm −2 for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), along with the smallest Tafel slope, signifying rapid reaction kinetics. Electrochemical impedance spectroscopy revealed its low charge-transfer resistance, while cyclic voltammetry and stability tests confirmed excellent durability and a large electrochemical surface area. Furthermore, CrNiFe-LDH-NF-ThU2 demonstrated the highest mass activity compared to benchmark catalysts (Pt and IrO₂/RuO₂), underscoring its efficiency. Highlights • NiFeCr-LDH-NF-CH₄N₂S₂ shows exceptional bifunctional activity for both OER and HER. • Requires low overpotential at 100 mA cm −2 with the smallest Tafel slope. • Exhibits low charge-transfer resistance, large ECSA, and superior durability. • LTH-NF-ThU₂ surpasses Pt and IrO₂/RuO₂ in mass activity. • Promising candidate for practical water electrolysis and sustainable energy applications.