Structural evolution induced by Au atom diffusion in Ag2S

Atom diffusion processes govern the structure and composition of core–shell nanomaterial, which play a crucial role in determining their properties. By using aberration-corrected high-resolution transmission electron microscopy and X-ray absorption near-edge structure spectroscopy in combination with in situ X-ray diffraction, we confirm that single-atom diffusion of Au to Ag2S occurs, and that the transition from the Au@Ag2S core–shell nanostructure to AuAgS–AuAgx or Ag3AuS2–AuAgx heterostructures was observed. Moreover, the phase of the ternary sulfide induced by Au single-atom diffusion in Ag2S is determined by the ratio of Au and Ag, thus exhibiting a significant difference in the photocatalytic activity performance.