Two Dimension C3N4/MoS2 Nanocomposites with Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation

Abstract

MoS2-decorated C3N4 (C3N4/MoS2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension (2D) C3N4 and MoS2 nanosheets. The effects of MoS2 content on the light absorption, charge transfer and photocatalytic activity of the hybrid samples were investigated. Characterization results show that MoS2 nanosheets are well anchored on the face of C3N4 nanosheets and the composites have well dispersed layered morphology. After loading with MoS2, the light absorption of composites was much improved, especially in visible-light region. The photocatalytic activities of C3N4/MoS2 samples were evaluated based on the H2 evolution under visible light irradiation (λ > 400 nm). When the loading amount of MoS2 was increased to 5 wt%, the highest H2 evolution rate (274 μmol·g-1·h-1) was obtained. Compared with samples obtained from direct impregnation method, sonication pretreatment is favorable for the formation of 2D layered heterojuctions and thus improve the photocatalytic activity. Slightly deactivation of C3N4/MoS2 composites could be observed when recycled due to the mild photocorrosion of MoS2. Based on the band alignments of C3N4 and MoS2, a possible photocatalytic mechanism was discussed, where MoS2 could efficiently promote the separation of the photogenerated carriers of C3N4.