The Structure-Controlling Solventless Synthesis and Optical Properties of Uniform Cu2S Nanodisks

Uniform Cu2S nanodisks have been synthesized from a well-characterized layered copper thiolate precursor by structure-controlling solventless thermolysis at 200-220 degrees C under a N-2 atmosphere. The development from small Cu2S nanoparticles (diameter approximate to 3 nm) to nanodisks (diameter 8.3 nm) and then to faceted nanodisks (diameter 27.5 nm, thickness 12.7 nm) is accompanied by a continuous phase transition from metastable orthorhombic to monoclinic Cu2S, the ripening of small particles by aggregation, and finally the crystallization process. The growth of the nanoproduct is constrained by the crystal structure of the precursor and the in situ-generated thiol molecules. Such controlled anisotropic growth leads to a nearly constant thickness of faceted nanodisks with different diameters, which has been confirmed by TEM observations and optical absorption measurements.