Integrating NiCo2S4 chalcogenide with FeP and Fe2P phosphides for enhanced oxygen evolution reaction efficiency

This work examines the catalytic performance of Ni-Co chalcogenide composites integrated with FeP and Fe₂P metal phosphides for the oxygen evolution reaction (OER). The synthesized NiCo₂S₄, NiCo₂S₄@FeP, and NiCo₂S₄@Fe₂P catalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). XRD analysis confirmed the effective inclusion of FeP and Fe₂P into the NiCo₂S₄ matrix, with characteristic peaks indicating a cubic spinel structure and crystalline iron phosphides. SEM images revealed that the composites exhibited distinct morphologies with FeP and Fe₂P particles dispersed across the NiCo₂S₄ surface, providing additional active sites for catalytic reactions. XPS spectra demonstrated the elemental composition and chemical states of the catalysts, confirming the presence of Ni, Co, Fe, P, and S elements. Electrochemical measurements, including linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), showed that the composite catalysts exhibited enhanced OER activity compared to their individual components. NiCo₂S₄@FeP displayed the highest catalytic performance with overpotential of 322 mV at a current density of 500 mA cm⁻² and maintained stability for over 96 h, making it a promising candidate for efficient and durable water-splitting applications.