Noble metal-free Ni-Mo-S nanoparticles modified graphitic C3N4 for efficient hydrogen evolution was successfully synthesized by means of a simple hydrothermal ion exchange process. This composite photocatalyst exhibits about 14 times higher photocatalytic activity of hydrogen production than that of the pure g-C3N4. Fluorescence analysis and electrochemical characterization confirmed that molybdenum sulfide and nickel sulfide as catalyst significantly enhanced the transfer of electrons on g-C3N4 and resulted in the excellent synergistic effect in photocatalytic properties. The promoted charge separation was measured by means of the EIS, photocurrent and transient fluorescence. A series of studies shown that the NixMo1-xS2 nanoparticles modified on the surface of graphitic C3N4 provided the more active sites and improved the efficiency of photo-generated charge separation with several characterizations such as SEM, XRD, XPS, element mapping, UV-vis DRS, Transient photocurrent and BET etc. and the results of which were in good agreement with each other. The composite photocatalyst g-C3N4/NixMo1-xS2 has a greater specific surface area and pore volume compared to pure g-C3N4, which is more favorable for the adsorption of dye molecules, leading to enhance the composite photocatalytic activity consequently. The excited-electron recombination process were greatly modulated with the introduce Ni-Mo-S nanoparticles on the surface of g-C3N4 and the photostability was enhanced as well. In addition, a possible reaction mechanism over eosin Y-sensitized g-C3N4/NixMo1-xS2 photocatalyst under visible light irradiation was proposed. (C) 2017 Elsevier B.V. All rights reserved.