Coupling of MoS2 nanosheets into Ag2CO3 micro-blocks to strengthen their photocatalytic performance in degradation of phenol and dyes

Abstract

In order to solve the photocatalytic corrosion problem of Ag₂CO₃ nanocrystals, MoS₂ nanosheets were prepared by a hydrothermal method, and subsequently the produced MoS₂ nanosheets were coupled with Ag₂CO₃ micro-blocks by a precipitation method. The SEM images show that the morphology of the MoS₂/Ag₂CO₃ composite samples is similar to that of Ag₂CO₃. From the high resolution TEM image, a close contact interface between MoS₂ and Ag₂CO₃ was observed over the MoS₂/Ag₂CO₃ composite. The photocatalytic performance test for removal of phenol and acid orange II under visible light (λ > 420 nm) illumination showed that the coupling of MoS₂ significantly improved the stability and activity of Ag₂CO₃. With the optimal content of MoS₂ (15 wt%), the degradation rates of phenol and acid orange II over MoS₂/Ag₂CO₃ reached 93 and 95% after 100 min of light irradiation, which were more than 1.5 and 0.5 times higher than those of Ag₂CO₃ and MoS₂, respectively. The UV-vis diffuse reflectance and electrochemical tests indicated that the light absorption range of MoS₂/Ag₂CO₃ is enlarged, and the excited electrons on the conduction band of MoS₂ are easily transferred to the conduction band of Ag₂CO₃ and the holes on the valence band of Ag₂CO₃ are transferred to the valence band of MoS₂. The enhanced separation of photogenerated electrons (e⁻) and holes (h⁺) contributed to more ˙O²⁻ and ˙OH radicals over 15% MoS₂/Ag₂CO₃ to degrade organic pollutants, and the photo-corrosion of Ag₂CO₃ was also suppressed at the same time.