1：Experimental Design and Method Selection:

A two-step hydrothermal method was used to synthesize core–shell NiS2@MoS2 nanospheres anchored on reduced graphene oxide (rGO) nanosheets. The combination ratio was adjusted to optimize impedance matching.

2：Sample Selection and Data Sources:

Samples were prepared with different reagent ratios (Sample A, B, C) as listed in Table 1, using chemicals from specified suppliers.

3：List of Experimental Equipment and Materials:

Equipment included a Bruker D8 Advanced X-ray diffractometer (XRD), Hitachi S4800 FE-SEM, JEL-2100F TEM/EDS, Tecnai G2 F20 HRTEM, ESCALAB 250 XPS spectrometer, and Agilent N5224A vector network analyzer (VNA). Materials included nickel chloride hexahydrate, ethylene glycol, ammonium molybdate, thiocarbamide, GO powder, and wax for composites.

4：Experimental Procedures and Operational Workflow:

NiS2 nanospheres were synthesized hydrothermally at 200°C for 12 hours. Then, NiS2@MoS2/rGO composites were prepared by adding NiS2 to a mixture of GO, ammonium molybdate, and thiocarbamide, followed by hydrothermal reaction at 200°C for 12 hours. Samples were characterized using XRD, SEM, TEM, XPS, and EM absorption measurements with VNA.

5：Data Analysis Methods:

Electromagnetic parameters (complex permittivity and permeability) were derived from scattering parameters measured by VNA. Reflection loss (RL) was calculated using transmission line theory equations. Attenuation constant and impedance matching ratio were analyzed to evaluate absorption performance.