Ni-Mo-S nanoparticles modified graphitic C3N4 for efficient hydrogen evolution

Abstract 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.