In situ light-assisted preparation of MoS2 on graphitic C3N4 nanosheets for enhanced photocatalytic H2 production from water
MoS2-decorated graphitic C3N4 (g-C3N4/MoS2) photocatalysts were prepared by a simple and scalable in situ light-assisted method. In this process, MoS2 was formed from the reduction of [MoS4]2− by photogenerated electrons, and was then loaded in situ on the electron outlet points of g-C3N4. The g-C3N4/MoS2 composite was well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and ultraviolet visible diffuse reflection spectroscopy (UV-DRS). The g-C3N4/MoS2 photocatalysts showed good photocatalytic H2 evolution activity. When the loading amount of MoS2 was increased to 2.89 wt% (g-C3N4/MoS2-2.89%), the highest H2 evolution rate (252 μmol g−1 h−1) was obtained. In addition, g-C3N4/MoS2-2.89% presented stable photocatalytic H2 evolution ability (no noticeable degradation of photocatalytic H2 evolution was detected in 18 h) and good natural light driven H2 evolution ability (the H2 evolution rate was 320 μmol g−1 h−1). A possible photocatalytic mechanism of the MoS2 cocatalyst for the improvement of the photocatalytic activity of g-C3N4 is proposed, where MoS2 can efficiently promote the separation of the photogenerated electrons and holes of g-C3N4, consequently enhancing the H2 evolution activity; this mechanism is supported by the photoluminescence spectroscopy and photoelectrochemical analyses.