Enhanced visible light photochemical activity and stability of MoS2/Cu2O nanocomposites by tunable heterojunction

Here we report the hydrothermal synthesis of MoS2/Cu2O nanocomposites with tunable heterojunction for enhancing visible light photochemical activity and stability. The conduction and valence band positions of few-layers MoS2 have been tuned to optimize photo-induced charge separation efficiency by regulating the layer thickness of MoS2. The photochemical activity and stability of MoS2/Cu2O nanoparticles are demonstrated by visible light assisted degradation of methyl orange. Among all of the samples, the MoS2/Cu2O nanocomposite assembled with 6000 rpm centrifuged MoS2 has the highest degradation efficiency of 95.8 % after 3 h of visible light illumination, due to the high visible light absorption and optimized electron-hole separation by the tunable heterojunction design. The influence of MoS2 mass ratio was further investigated. At last, for better understanding of the enhanced photochemical activity, a novel charge separation mechanism is proposed based on the band alignment and build-in electric field between Cu2O and MoS2.