Low temperature growth of CuS nanoparticles by reflux condensation method

We report a facile, low-temperature soft solution route to synthesize copper sulfide (CuS) nanomaterials with different morphologies by reflux condensation method. CuS nanomaterials were synthesized without the assistance of additional surfactant or templates, and the influence of key synthetic parameters namely solvent medium and sulfur source on the final structure of CuS was comprehensively investigated. XRD pattern of the synthesized products revealed the formation of hexagonal structure of covellite CuS. SEM analysis showed that the CuS products synthesized in water were ball-like microspheres and the products prepared in ethanol were spherical shaped CuS nanocrystals, but those synthesized in ethylenediamine were flower-like CuS hierarchical network consisting of self-assembled nanoflakes as primary building units. DRS exhibited the characteristics broadband absorption of CuS in near-IR region. The optical band gap of the CuS nanocrystals was in the range between 2.35 eV and 2.81 eV, exhibiting considerable blue shift due to quantum size effects. Electrical resistivity measurements confirmed the semiconducting nature of CuS. On the basis of experimental results, the plausible formation mechanism of different CuS nanostructures was put forward and discussed briefly.