Phase-Selective Synthesis of Copper Phosphosulfide Nanocrystals

Abstract Copper phosphosulfides, including Cu7PS6 and Cu3PS4, are important materials for their ionic, electronic, and thermal conductivity properties. However, nanocrystals of these copper phosphosulfides are surprisingly rare. Here, we show that both Cu7PS6 and Cu3PS4 nanocrystals can be synthesized by reacting CuCl, P2S5, 1-dodecanethiol, and oleylamine at 250 °C for 1 h, with all reagents playing key roles in the synthesis. Phase selectivity is achieved by controlling reagent concentration, which is related to the reaction chemistry that is implicated in the formation of the nanocrystal products. Cu7PS6 forms tetrahedron-shaped nanocrystals while Cu3PS4 forms tetrapods, which can be rationalized by crystal structure relationships. The successful formation of Cu7PS6 and Cu3PS4 represents an important addition to the library of synthetically accessible nanocrystals with well-defined morphologies.