Shape Control of Ternary Sulfide Nanocrystals

Abstract

Synthesis of semiconductor nanocrystals with a definite shape is the foundation of their anisotropy properties investigation; however, it is more challenging in ternary metal sulfides than that of noble metal and binary sulfides. In this paper, we report a solvent polarity control strategy to prepare a family of ternary sulfide (Ag 3 SbS 3 ) semiconductor nanocrystals with tunable polyhedral shapes. The crystal growth speed along different directions was confined by the capping effect of the polarity of solvents that was defined by reaction temperature. Crystal shape of Ag 3 SbS 3 nanocrystals could be tailored as a sphere, hexagonal plate, and prism. A shape-controllable growth mechanism was analyzed based on the Bravais−Friedel− Donnay−Harker theory by taking crystal structure characteristics and the polarity of solvents into consideration. The semiconductor nanocrystals show a near value of the band gaps for different shaped samples and facetdependent photocatalytic water-splitting activities, which may result from the discrimination of the terminal surface structure and binding energy of Sb and S for the three different shaped nanocrystals. Thus, we provide a new crystal shape tunable strategy for ternary sulfide nanocrystal synthesis, which is important for optimizing properties and applications of sulfide semiconductor nanocrystals.

Near‐Infrared Luminescent Ternary Ag3SbS3 Quantum Dots by in situ Conversion of Ag Nanocrystals with Sb(C9H19COOS)3

“…The peaks centered at 161.4 and 162.5 eV implied that S is in anionic form, which agrees well with literature . These observed binding energies are in agreement with reported data in Ag 3 SbS 3 nanostructures…”

“…XPS spectra are used to determine the surface chemical composition of the as‐prepared sample. As shown in Figure , Ag, Sb, S, and O are detected and the presence of O (532 eV) is attributed to the oxygen adsorption . The high‐resolution Ag 3d spectrum (Figure , left) shows two symmetric peaks due to spin‐orbit splitting with binding energies of 373.8 and 367.8 eV for the d 3/2 and d 5/2 lines, indicating that Ag presents only in the Ag + state .…”

“…All of the peaks match those of hexagonal Ag 3 SbS 3 (pyrargyrite type, space group R 3 c (No. 161)), and the calculated lattice constants were a=b=11.047Å, and c=8.719 Å (JCPDS 21–1173) . As shown in inset of Figure B, each Sb atom is bonded to three S atoms, forming a pyramidal SbS 3 unit, the Ag atoms are located in pyramids .…”

“…Such in situ conversion could achieve controllable composition and morphological retention. As an important ternary narrow band gap semiconductor, pyrargyrite, Ag 3 SbS 3 , is a layered semiconductor with a direct (experimental) band gap between 1.5 and 1.7 eV and high absorption coefficient . Ag 3 SbS 3 with hexagonal crystal phase, showed potential applications as a thermoelectric, a nonlinear optical material, and a photocatalyst .…”

“…Ag 3 SbS 3 with hexagonal crystal phase, showed potential applications as a thermoelectric, a nonlinear optical material, and a photocatalyst . Ag 3 SbS 3 thin films, along with different shapes of Ag 3 SbS 3 NCs, as sphere, hexagonal plate, prism and nanorod, have been realized through both thermally‐evaporated methods or hydrothermal methods. These existing methods exposed some major drawbacks, such as toxic ligands and high temperature.…”