Characterization and hydrogen evolution reaction performance of KIT-6-derived mesoporous carbon supported transition metal sulfides

Abstract

Aiming to create electrocatalysts for the hydrogen evolution reaction (HER), this work looks at the synthesis and characterization of transition metal sulfides (FeS, NiS, and MoS2) supported on CMK-8 type mesoporous carbon (MC) materials. The synthesized catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscope (SEM), and electrochemical performance tests such as linear scanning voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). All the synthesized catalysts were compatible with the Type-IV isotherm, which indicates the mesoporous structure and MC exhibited the highest surface area of ​​1157 m2/g. While the crystal structure of the Ni-S catalyst consisted of NiSO4.6H2O and NiS2 compounds, only peaks belonging to FeS2 and MoS2 crystals were observed in the Fe-S and Mo-S catalysts, respectively. In MC supported catalysts, it is predominantly in the amorphous carbon structure belonging to the support. Further improvement of the support-catalyst interaction is required, as evidenced by the notably high overpotential of 460 mV displayed by the Ni-S@MC catalyst and the much lower overpotential of 232 mV by Ni-S. The charge transfer resistance values were found to vary, according to impedance analysis. Ni-S demonstrated the lowest resistances (18.5 Ω at -0.3 V), highlighting its better electron transfer capabilities over other catalysts. The larger overpotentials from MC’s enhanced surface area underscore the trade-off between maximizing kinetics and preserving low energy barriers. These results highlight the possibilities and difficulties of employing metal sulfides on MC substrates for effective and long-lasting HER applications.