Phase controlled synthesis of copper sulfide nanoparticles by colloidal and non-colloidal methods

Abstract

Bis(O-alkylxanthato)copper(II) (alkyl = Et (1), Hex (2) and Oct (3)) complexes were synthesized and used as single source precursors for the synthesis of copper sulfide nanoparticles by thermolyses in oleylamine, solid state deposition and doctor’s blade method at different temperatures and reaction times. The p-XRD pattern of the copper sulfide nanoparticles obtained from complex (1) by colloidal thermolysis in oleylamine show pure Digenite phase (Cu9S5) under all reaction conditions. TEM images show significant changes in size and shape of crystallites by variation of the growth temperature or time. Thermolysis of complex (2) in oleylamine gave pure phase Digenite (Cu9S5) at higher temperature (250 °C) with disks and rectangular cuboidal morphologies whereas at lower temperature (200 °C) traces of Covellite (CuS) were also observed. The p-XRD analysis of the nanoparticles produced from the thermolysis of complex (3) in oleylamine show Digenite (Cu9S5) as the predominant phase with some impurity of Djurleite (Cu31S16) phase. The melt method produced Digenite and Covellite phases from complex (1) and pure Digenite phase from complex (2). Complex (3) gave the Digenite and Chalcocite phases. Nanoparticles from all three complexes by the melt method show spherical and cuboid morphology. p-XRD of thin films by the doctor blade method show Digenite as the major phase and Djurleite as the minor phase. These results showed that the phase of copper sulfide were directly dependent on the type of precursor (alkyl chain length), growth temperature and the method used.