Controlled synthesis and characterization of covellite (CuS) nanoflakes

Trigonal and hexagonal CuS (covellite) nanoflakes with controlled size (10–200 nm, and thickness of 3.6–5 nm) were synthesized through the reaction between copper acetylacetonate and sulfur in oleylamine. Size and shape of the products could be tuned by reaction parameters and reactant concentration. The as-prepared flakes have smooth surfaces and self-assemble face-to-face each other. High-resolution transmission electron microscopy and electron diffraction show that the nanoscale flakes were single-crystal hexagonal covellite. Formation mechanism of the nanoflakes is discussed. UV–vis spectra reveal that the samples have blue-shift absorbance onsets owning to the quantum size effects.