Structure based optical properties and catalytic activities of hydrothermally prepared CuS nanostructures.

The nano-sized copper sulfides (CuS) with different morphologies were prepared by hydrothermal method without any surfactant or template. The morphology and structure of CuS were characterized by powder x-ray diffraction (XRD), Fourier transform infrared spectroscopy, x-ray photoelectron spectra (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) and ultraviolet-visible (UV-vis) absorption spectroscopy. FESEM results show that four morphologies of CuS (flower-like nanospheres, cross-linked nanodisks, cross-linked nanoplates and nanosheets) were prepared simply by changing the hydrothermal solvent. According to the XPS, XRD and HRTEM results the synthesized nano-sized structures are highly crystallized pure hexagonal covellite CuS. UV-vis spectra results show intense absorption peaks in the visible region, confirming that the resultant CuS has potential application in the field of solar cells. The catalytic activities of resultant CuS on model pollutant methylene blue (MB) in the dark were also investigated in detail. The small and flat crystallites show rapid degradation rate on MB, which is attributed to the numerous active sites on their large specific surface area. The as-synthesized CuS nanosheets took the shortest time (only 15 min) to degrade MB completely compared with the other nanostructural CuS in this work as well as previously reported ones. Total organic carbon removal of the samples approved mineralization of the MB pollutant. Thus, CuS is an excellent catalyst for degrading organic pollutants, which does not require light energy for its catalytic activities.