Dual synergetic effects in MoS₂/pyridine-modified g-C₃N₄ composite for highly active and stable photocatalytic hydrogen evolution under visible light

Composite photocatalysts with nanoflower-structured MoS₂ grown on pyridine-modified graphitic carbon nitride (g-C₃N₄) have been synthesized through a facile in situ solvothermal approach. These composites demonstrate greatly enhanced response to visible light, and consequently remarkably enhanced hydrogen evolution performance by photocatalytic water splitting. The addition of 2,5-dibromopyridine during the formation process of g-C₃N₄ can not only enhance the photocatalytic activity but also the durability of the photocatalysts. The MoS₂ content and the ratio between 2,5-dibromopyridine and g-C₃N₄ in these composites can be well tuned to obtain the optimized photocatalytic activity with a peak H₂ production rate of 25 μmol h^-1 on 50 mg photocatalyst without adding any noble metal under visible light irradiation at 283 K. A dual synergetic mechanism in MoS₂/pyridine-modified g-C₃N₄ composite, which is featured with significantly promoted separation of photo-generated carriers and stability of S^2- and/or S₂^2- in the composites under visible light irradiation, has been proposed to account for the distinguished hydrogen evolution activity and stability of these composite photocatalysts.