Facile one-pot synthesis of polytypic CuGaS2 nanoplates

Abstract

CuGaS2 (CGS) nanoplates were successfully synthesized by one-pot thermolysis of a mixture solution of CuCl, GaCl3, and 1-dodecanethiol in noncoordinating solvent 1-octadecene. Their morphology, crystalline phase, and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. Crystalline structure analysis showed that the as-prepared CGS nanoplates were polytypic, in which the wurtzite phase was interfaced with zincblende domains. The growth process of CGS nanoplates was investigated. It was found that copper sulfide nanoplates were firstly formed and then the as-formed copper sulfide nanoplates gradually transformed to CGS nanoplates with proceeding of the reaction. The optical absorption of the as-synthesized CGS nanoplates was also measured and the direct optical bandgap was determined to be 2.24 eV.

Occurrence of Polytypism in Compound Colloidal Metal Chalcogenide Nanocrystals, Opportunities, and Challenges

“…The first example of polytypism in these multinary systems was randomly discovered by Korgel et al during CuInS 2 nanodisks synthesis, where the WZ phase interfaces with significant chalcopyrite (CH) domains across (002) WZ /(112) CH stacking faults. Later, different researchers found that during the colloidal synthesis, at lower temperatures, the metastable wurtzite form of CuInS 2 occurs as nanoplates, but as the number of metal cations decrease with further progression of the reaction, WZ–ZB polytypism occurs in the system. , Furthermore, partial or complete substitution of Ga or Fe in the crystal lattice of CuInS 2 to form CuInGaS 2 (CIGS), CuGaS 2 , or CuInFeS 2 also results into the occurrence of WZ–ZB or WZ–CH polytypism. − However, formation of branched morphologies or 1-D linear structures were not reported in Cu–In–Ga–S/Se systems.…”

Synthesis and Characterization of N-Type CuGaS2 Nanoparticles and Films for Purpose of Photoelectrocatalytic Water Splitting

“…Figure 5c is a typical highresolution spectrum of Ga 2p 3/2 and Ga 2p 1/2 levels that shows peaks centred at 1118.1 eV and 1144.9 eV, respectively, with a peak separation of 26.8 eV indicative of trivalent gallium. 50,51 Deconvolution of the XPS high-resolution spectrum of the S 2p level (Fig. 5d) reveals two peaks centred at binding energies of 161.1 eV and 162.3 eV, corresponding respectively to the S 2p 3/2 and S 2p 1/2 levels with a peak separation of 1.2 eV that is consistent with metal sulfide material showing a sulphur (−II) oxidation state.…”

“…48 The high-resolution spectrum of Cu 2p reveals two peaks centred at binding energies of 931.7 eV and 951.6 eV that can be assigned to Cu 2p 3/2 and Cu 2p 1/2 levels, respectively, consistent with the standard separation of 19.9 eV for chalcopyrite Cu (I) species. [49][50][51] In addition, the Cu 2p satellite peak assigned to Cu (II) species, which is usually centred at ∼942 eV, 52,53 does not appear in the spectrum. Figure 5c is a typical highresolution spectrum of Ga 2p 3/2 and Ga 2p 1/2 levels that shows peaks centred at 1118.1 eV and 1144.9 eV, respectively, with a peak separation of 26.8 eV indicative of trivalent gallium.…”

Mechanism of morphology variations in colloidal CuGaS2 nanorods

“…For example, restricting to CuGaS 2 , there are reports of at least 8 different variations on the common dot, platelet, and rod shapes, starting from Cu 2-X S seeds. [21][22][23][24][25][26] This combination of compositional and morphological diversity suggests that the Cu 2-X S system may be ideal for tailoring Figure 1. Transmission Electron Microscopy (TEM) images of CuGaS 2 NR growth from aliquots taken at 0 s, 30 s, 1 min, 2 min, and 5 min.…”