Silver-Based Metal Sulfide Heterostructures: Synthetic Approaches, Characterization, and Application Prospects

We present a simple solution-processed synthesis route to access several types of silver-based metal sulfide heterostructures. The route uses a seed-mediated strategy involving ex situ and in situ seed-mediated growth. An ex situ seed-mediated growth protocol was used to synthesize Ag 2 S/ZnS and Ag 2 S/CdS heterostructures, while the in situ seed-mediated growth provided control over the nucleation stage in the presence and absence of oleylamine, allowing for the preparation of either Ag@AIS or Ag 2 S/AIS heterostructures, respectively. The as-synthesized heterostructures could also subsequently act as a nucleation platform for the attachment of the exterior material (ZnS), yielding AgCdS/ZnS, Ag@AIS/ZnS, and AgInZnS heterostructured nanomaterials, in the same reaction vessel without intermediate seed purification. In particular, the length of Ag 2 S/ZnS nanorods was adjustable from 12 nm up to 450 nm by increasing injecting volume of the ZnS precursors. Based on the experimental results, we have also proposed a possible formation mechanism and the underlying factors that determine the morphology of silver-based metal sulfide heterostructures. In optical studies, the Ag 2 S/ZnS nanorods exhibited dual emission, including the NIR emission and blue emission attributed to the band-gap emission of Ag 2 S and ZnS, respectively. The synthesized Ag 2 S/CdS heterostructures showed an emission peak at 540 nm with a fluorescence lifetime of ∼2.5 μs, which is ∼1.5 orders of magnitude longer than that of CdS samples. Meanwhile, the potential for the Ag 2 S/CdS heterodimers as an effective sensitizer in photovoltaic devices was examined under AM 1.5G illumination.