Controlled Synthesis, Formation Mechanism, and Applications of Colloidal Ag8SnS6 Nanoparticles and Ag8SnS6/Ag2S Heterostructured Nanocrystals

Semiconductor nanocrystals (SC NCs) have attracted scientists' attention because of their size- and shape-dependent optical properties. Now, many scientists' research is focused on the synthesis of the earth-abundant and environmentally compatible SC NCs and their applications for solar energy conversion. Herein, colloidal silver-based I-IV-VI SC NCs, Ag8SnS6 nanoparticles (NPs) were synthesized. Ag8SnS6 NPs showed a strong quantum size confinement effect from optical measurement. The photocurrent response measurement showed a typical n-type property for Ag8SnS6 NPs. It is very interesting that colloidal Ag8SnS6/Ag2S heterostructured nanocrystals (HSNCs), containing drop-shaped and little bowtie-shaped HSNCs, can also be synthesized via changing the adding process of precursors in the beginning of the experiment. The first formation of Ag NPs is very important to form Ag8SnS6/Ag2S HSNCs. A seeded growth mechanism was proposed to explain the formation of Ag8SnS6/Ag2S HSNCs. The polycrystalline structure in the Ag2S NP seed played an important role to synthesize drop-shaped HSNCs. The synthetic method for Ag8SnS6/Ag2S HSNCs can provide an approach to synthesize branched HSNCs with polycrystalline seeds. Moreover, Ag8SnS6 NPs showed potential for solar energy conversion.