High photocatalytic activity of g-C3N4/CdZnS/MoS2 heterojunction for hydrogen production

Abstract

In an effort to improve the light absorption efficiency of the photocatalyst, g-C3N4 nanosheets with visible light response have been prepared by roasting method, and the g-C3N4/CdZnS composite catalyst with 2D/0D architecture has been prepared by hydrothermal method after ultrasonic thinning. The g-C3N4/CdZnS/MoS2 composite catalyst with 2D/0D architecture has been synthesized by secondary hydrothermal method. TEM analysis proves that a close heterogeneous interface has been formed between g-C3N4 and CdZnS, and between CdZnS and MoS2. The ultraviolet diffuse reflectance spectrum shows that MoS2 has a wide light absorption range, which effectively enhances the light utilization ratio of the composite catalyst. The energy band structure diagram and photoelectrochemical test results show that a continuous stepped type II ternary heterojunction is formed among g-C3N4, CdZnS and MoS2, which promotes its separation of photogenerated charges. When the loading mass fraction of g-C3N4 and MoS2 is 4%, the hydrogen evolution rate of g-C3N4/CdZnS/MoS2 composite catalyst is 57.02 mmol g−1 h−1 under visible light, which is exceeding 20% that of g-C3N4/CdZnS and 4.79 times and 44.9 times higher than that of CdZnS and g-C3N4, respectively. The two-dimensional structure of g-C3N4 and MoS2 significantly improves the stability of the composite catalyst. This work offers feasible ways for ternary heterogeneous photocatalyst construction.