Electrochemical synthesis and optical characterization of copper selenide nanowire arrays within the alumina pores

By choosing an appropriate aqueous solution containing CuSO4, H2SeO3, MgSO4, and H2SO4 the suitable composition for two- or one-phase copper selenide deposition within the alumina pores under alternating current (AC) electrolysis conditions was created. X-ray diffraction spectra recorded within 15–55° 2Θ range revealed fabrication of Cu3Se2+Cu2−xSe or almost pure Cu2−xSe crystalline material. The compositional and morphological studies using XRD, EDX, SEM, and TEM techniques show fabrication of nearly pure Cu2−xSe with some deficiency of copper, say, Cu1.75Se, nanowires in length up to several microns when the selenious acid to copper–ion ratio is close to 1:2 and pH of the bath is <1.25. The fundamental absorption spectrum for this nanostructured material was shown to be formed by allowed direct and indirect interband transitions with the evaluated energy band gaps 2.3 and 1.1 eV, respectively.