Engineering of tunable Au-Ag2S heterostructures: A study of morphology-induced visible-light photocatalytic performance by SERS

Efficient visible-light photocatalysts are essential for energy and environmental sustainability. Many efforts have been devoted to designing diverse heterostructures in the pursuit of high-performance photocatalysts. However, the effect of morphology of the heterostructures on the photocatalytic performance still needs to be further explored. Here, tunable Au-Ag2S heterostructures were synthesized to investigate the morphology-induced photocatalytic performance by surface-enhanced Raman scattering (SERS) spectroscopy. All the Au-Ag2S heterostructures possess remarkable visible-light photocatalytic and SERS activity compared with Au or Ag2S. Moreover, with increasing exposure of the Au component, the Janus heterostructures display better photocatalytic performance than the heterostructures with other morphologies. The possible mechanism is that the axially separated structure enhances the plasmon-induced electron-hole separation and facilitates interfacial charge transfer in the anisotropic heterostructures, owing to a stronger plasmon-enhanced near field. The photocatalytic degradation efficiency of methylene blue by the Au-Ag2S Janus heterostructures reached 93.9% within only 60 s. The photocatalytic degradation rate is 2.38, 1.53 and 1.48 times higher than that of the core–shell, eccentric core–shell-I and eccentric core–shell-II heterostructures. Our work demonstrates that the morphology of the Au-Ag2S heterostructures exhibits a significant effect on the visible-light photocatalytic performance, which opens a new pathway toward the design of heterostructures for high-performance photocatalysis.