Preparation and phase transformation of nanocrystalline copper sulfides (Cu9S8, Cu7S4 and CuS) at low temperature

Abstract

Nanocrystallites of non-stoichiometric copper sul®des were synthesized via the reaction between [Cu(NH 3 ) 4 ] 2z and thiourea in sealed autoclaves at the low temperature of 60 ³C for 3 h. Thiourea played a key role in the process of Cu 9 S 8 nanocrystal formation. Through adjusting the redox atmosphere, Cu 7 S 4 and CuS were obtained from the freshly formed Cu 9 S 8 nanocrystals. The products were characterized by means of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy and transmission electron microscopy (TEM) techniques. The Cu : S atomic ratios for Cu 9 S 8 and Cu 7 S 4 were 9 : 8.08 and 7 : 4.05, respectively, analyzed by inductively coupled plasma (ICP) spectroscopy. The possible mechanism of phase transformation among copper sul®des (Cu 9 S 8 , CuS, and Cu 7 S 4 ) was discussed. The optical properties of the products were also recorded by means of UV±vis absorption, and photoluminescence spectroscopy.

Synthesis of Copper Sulfide Nanowhisker via Sonochemical Way and Its Characterization.

“…In their UV-vis absorption spectra, both have a wide absorption shoulder from 600 nm to 500 nm, agreeing with the literature value 16 for Cu 9 S 8 nanoparticles that do not assemble to form whisker-like crystal. However, for whisker-like Cu 9 S 8 the other absorption appears at 250 nm, which may be attributable to low dimension of whisker-like Cu 9 S 8 .…”

Quantum Dot–Sensitized Solar Cells Featuring CuS/CoS Electrodes Provide 4.1% Efficiency

“…The CuS ( K sp = 5 × 10 − 36 ) electrode provided a broad absorption band in the region between 400 and 650 nm, supporting the formation of CuS microstructures. [ 19 ] The CuS electrode also had a characteristically broad absorption band, resulting from an electron-acceptor state lying with the bandgap ( E g ). [ 20 ] Through extrapolation of the plot of (OD × h ν ) 2 with respect to h ν , where OD is the optical density, we estimated the value of E g for the CuS electrode to be 2.46 eV, [ 21 ] which is considerably larger than that of bulk CuS (2 eV).…”

Self‐assembly of Copper Sulfide Nanoparticles to Solid, Hollow Spherical and Wire‐Shaped Structures

“…In order to compare with the obtained results, samples S1, S2 and S3 are listed in Table 1, which were cited from the reference. 22 The diffraction peaks of samples S3 and S4 match well with the standard peaks of orthorhombic phase Cu 7 The morphologies of the obtained samples were determined by SEM. The typical SEM images of the samples are shown in Figure 2.…”

“…It is notable that the copper-thiourea system has already been utilized to generate copper sulfides in various forms and compositions, 7,14 and its chemistry is clearly complicated as a result of the ready redox between them in combination with the complex copper-sulfur stoichiometry. This attracted our interest to explore the potential growth mechanism of copper sulfide crystals under the present hydrothermal reaction conditions.…”