Synthesis and characterization of composite visible light active photocatalysts MoS2–g-C3N4 with enhanced hydrogen evolution activity

Molybdenum disulfide (MoS2) and graphitic carbon nitride (g-C3N4) composite photocatalysts were prepared via a facile impregnation method. The physical and photophysical properties of the MoS2–g-C3N4 composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microcopy (HRTEM), ultraviolet–visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The photoelectrochemical (PEC) measurements were tested via several on–off cycles under visible light irradiation. The photocatalytic hydrogen evolution experiments indicate that the MoS2 co-catalysts can efficiently promote the separation of photogenerated charge carriers in g-C3N4, and consequently enhance the H2 evolution activity. The 0.5wt% MoS2–g-C3N4 sample shows the highest catalytic activity, and the corresponding H2 evolution rate is 23.10 μmol h−1, which is enhanced by 11.3 times compared to the unmodified g-C3N4. A possible photocatalytic mechanism of MoS2 co-catalysts on the improvement of visible light photocatalytic performance of g-C3N4 is proposed and supported by PL and PEC results.