Single-crystal snowflake of Cu7S4: Low temperature, large scale synthesis and growth mechanism

Non-stoichiometric copper sulfides (Cu7S4), with uniform hexapetalous snowflake-like morphology in high yield have been synthesized successfully by a simple and facile one-step solvothermal route with a low temperature (150 °C). Copper chloride and thiourea were chosen as the reactants in an ethylenediamine solution. The role of ethylenediamine as a structure-directing coordination molecular template responsible for the morphologies of the copper sulfides and its role as a reducing agent for the non-stoichiometric have been discussed. In addition, temporal growth of the dendrites can be readily followed in this preparation via time-resolved microscopic analysis. The formation mechanism based on the experiments has been proposed.