Transformation of Nanostructures CuO to CuSe through Different Routes and the Effect on Photocatalytic Properties.

In this work, copper selenide (CuSe umangite phase) was synthesized by two routes, using a chemical reaction and the hydrothermal method to obtain CuSe-A and CuSe-H, respectively. The synthesis of CuSe consisted of a three-step process: in the first step, copper(I) oxide hexapods (CuO) were obtained as the copper reservoir; in the second step, selenium ions were obtained from the reduction of selenium powder; and in the third step involves mixing two precursors following the two synthesis routes mentioned before. Analysis of X-ray diffraction and X-ray photoelectron spectroscopy showed the formation of the CuSe phase by both synthesis routes. On the other hand, using the scanning electron microscopy (SEM) technique, it is observed that the CuSe sample (CuSe-A) is obtained by exchanging in solution with agitation and that the copper selenium phase grows only on the surface of the hexapods. Meanwhile, the hydrothermal route promotes a total conversion of copper(I) oxide hexapods to the copper selenide phase (CuSe-H). The resulting materials were tested as photocatalytic materials to remove methylene blue dye in water under sunlight irradiation. CuSe (CuSe-H) obtained by the hydrothermal route exhibited a higher efficiency of photodegradation of dye, reaching a removal percentage of 92% after 4 h under sunlight.