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.