Simple Synthesis of Copper and Silver Sulfides under Hydrothermal Condition

Pure copper (II) sulfide, CuS, was successfully prepared by a simple reaction of copper and sulfur powder in water at low temperatures (less than 60 °C), though the solid state reaction of the elements requires higher temperatures to complete the reaction. Pure Copper (I) sulfide (Cu2S) and silver (I) sulfide (Ag2S) were also prepared by similar reactions between the elements above 150 °C and 90 °C, respectively. Two phases (chalcocite-Q and chalcocite-low) were observed in the yielded Cu2S. Observation with the scanning electron microscope revealed that the CuS was composed of the particles of polyhedral frameworks with dimensions of 2 - 3 micro m. Whereas the particle sizes of the as-prepared Cu2S were similar to those of CuS, the particles had indefinite frameworks. For Ag2S, the as-prepared particles at 90 oC were like sharp thin blades and became duller with the increasing reaction temperature.