Synthesis of copper sulfide nanoparticles: pH dependent phase stabilization

Abstract

Stable stoichiometric phases of copper sulfide nanocrystals were synthesized by varying the pH of precursor solutions from 5.5–9.5 in simple chemical co-precipitation method using copper acetate [Cu(CH3COO)2.H2O] and Sodium thiosulfate Na2S2O3.5H2O as precursors. Phase formation has been confirmed by X-ray diffraction (XRD) which revealed that particles synthesized from solution at 9.5 pH, stabilized in pure covellite phase, at lower pH mixed phases of copper sulfide were obtained. Surface morphology of the nanoparticles probed by Scanning electron microscopy (SEM) show self assembled nanostructures due to agglomeration. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy are used to confirm the phases Optical band gap of nanopowders prepared at different pH varied from 3.27 eV to 3.66 eV. PL spectra show a broad peak at a wavelength of 470 nm for excitation wavelength of 353 nm.