An amorphous MoS x modified g-C 3 N 4 composite for efficient photocatalytic hydrogen evolution under visible light.

In this work, an MoS x /g-C 3 N 4 composite photocatalyst was successfully fabricated by a sonochemical approach, where amorphous MoS x was synthesized using a hydrothermal method with Na 2 MoO 4 ·H 2 O, H 4 SiO 4 (W 3 O 9 ) 4 and CH 3 CSNH 2 as precursors, and g-C 3 N 4 nanosheets were produced using a two-step thermal polycondensation method. The hydrogen-evolution performance of the MoS x /g-C 3 N 4 composite was tested under visible light. The results show that the H 2 -evolution rate of the MoS x /g-C 3 N 4 (7 wt%) photocatalyst reaches a maximum value of 1586 μmol g -1 h -1 , which is about 70 times that of pure g-C 3 N 4 nanosheets. The main reason is that amorphous MoS x forms intimate heterojunctions with g-C 3 N 4 nanosheets, and the introduction of MoS x into g-C 3 N 4 nanosheets not only enhances the ability to convert H + into H 2 , but also promotes the separation of photoinduced electron-hole pairs for the photocatalyst. BET analysis shows that the specific surface area and pore volume of g-C 3 N 4 are decreased in the presence of MoS x . XPS analysis manifests that MoS x provides a number of active sites. Mott-Schottky plots show that the conduction band of MoS x (-0.18 V vs. E Ag/AgCl , pH = 7) is more negative than that of g-C 3 N 4 nanosheets.