The solvothermal approach was used to synthesis a ZnS@g-C3N4 nanocomposite. To improve the photocatalytic qualities of the nanocomposite, two-dimensional g-C3N4 nanosheets were linked with ZnS spheres at various ratios to study the charge-carrier interactions. This connection was investigated using energy-dispersive X-ray spectroscopy, UV diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. The volatile organic compound methyl tert-butyl ether (MTBE) that was present in an aqueous solution was photodegraded using the produced nanocomposite. The ZnS sphere and gC3N4 nanosheet band gaps were discovered and the band gap energy of every synthetic material fell between +3.23 and +2.59 eV. Elemental analysis and X-ray diffraction also revealed a high-purity sample. The effectiveness of the nanocomposites were assessed in the photocatalytic destruction of MTBE when exposed to visible light. With degradation of over 100% for MTBE, the 30% ZnS@g-C3N4 nanocomposite materials demonstrated the highest photocatalytic activity. Furthermore, the photocatalytic decomposition kinetics rate of MTBE in the following sequence: g-C3N4 (0.0184 min-1 )  ZnS (0.0201 min-1 )  40% ZnS@g-C3N4 (0.0273 min -1 )  10% ZnS@g-C3N4 (0.0348 min-1 )  20% ZnS@g-C3N4 (0.0355 min-1 )  50% ZnS@g-C3N4 (0.0372 min-1 )  30% ZnS@g-C3N4 (0.0443 min-1 ) and follows a pseudo-first-order process with their corresponding rate constants as determined by kinetic studies. This investigation explains the interaction between the two surfaces in the ZnS@g-C3N4 nanocomposite, which produces a better performance than the individual components.