Dual-function efficient hydrogen evolution reaction electrocatalyst and electrode material for supercapacitors based on ternary composite FeS2/Fe2O3/MoS2 nanostructures

Hydrogen is a promising and environment-friendly energy source that can be produced in a highly efficient manner through water electrolysis. This process requires the use of effective electrocatalysts to facilitate the hydrogen evolution reaction (HER). In this study, the synthesis, characterization, and electrochemical performance of FeS₂, Fe₂O₃, a binary composite of FeS₂ and Fe₂O₃ (FeS₂/Fe₂O₃), and a ternary composite of FeS₂, Fe₂O₃, and MoS₂ (FeS₂/Fe₂O₃/MoS₂) are investigated. The materials were prepared using a hydrothermal technique and analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical assessments. The ternary composite demonstrated improved HER performance, with the FeS₂/Fe₂O₃/MoS₂ hybrid exhibiting the highest electrochemically active surface area ECSA (27.79 μF/cm²), and lowest charge transfer resistance R_ct (288 Ω), overpotential (96 mV vs. SHE at 10 mA/cm²) and Tafel slope (72 mV/decade), indicating the superior performance of the ternary composite in facilitating the HER. These results indicate that the combination of MoS₂ with FeS₂ and Fe₂O₃ greatly enhances the catalytic activity, making the ternary composite a highly attractive option for effective water-splitting applications. In addition, the hybrid composite exhibited outstanding supercapacitor performance, with a specific capacitance of 171.42 F/g at a current density of 1 A/g. These results indicate that FeS₂/Fe₂O₃/MoS₂ can function as a highly effective electrocatalyst for the HER and is a superior material for supercapacitors.