Formation of Cu2−xSe(en)2 in a solvothermal process and conversion to nanocrystalline Cu2−xSe

A precursor to prepare nanocrystalline Cu2−xSe was obtained in the solvothermal reaction of CuCl2·2H2O with elemental selenium at 140°C for 10 h in ethylenediamine (en). Powder X-ray diffraction (XRD), infrared (IR) spectroscopy, thermal analyses (TGA-DTA), and inductively coupled plasma (ICP) analyses showed that the precursor could be a complex with the form Cu2−xSe(en)2, which released the ligand ethylenediamine to obtain Cu2−xSe crystals by pyrolysis or protonation. XRD, transition electron spectroscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to investigate the phase, size, morphology, and composition, respectively, of the final product. The analyses indicated that it was a pure nanocrystalline Cu2−xSe with cubic structure.