Shape Control of Colloidal Cu_2–xS Polyhedral Nanocrystals by Tuning the Nucleation Rates

Abstract

Synthesis protocols for colloidal nanocrystals (NCs) with narrow size and shape distributions are of particular interest for the successful implementation of these nanocrystals into devices. Moreover, the preparation of NCs with well-defined crystal phases is of key importance. In this work, we show that Sn(IV)-thiolate complexes formed in situ strongly influence the nucleation and growth rates of colloidal Cu2–xS polyhedral NCs, thereby dictating their final size, shape, and crystal structure. This allowed us to successfully synthesize hexagonal bifrustums and hexagonal bipyramid NCs with low-chalcocite crystal structure, and hexagonal nanoplatelets with various thicknesses and aspect ratios with the djurleite crystal structure, by solely varying the concentration of Sn(IV)-additives (namely, SnBr4) in the reaction medium. Solution and solid-state 119Sn NMR measurements show that SnBr4 is converted in situ to Sn(IV)–thiolate complexes, which increase the Cu2–xS nucleation barrier without affecting the precursor conversion rates. This influences both the nucleation and growth rates in a concentration-dependent fashion and leads to a better separation between nucleation and growth. Our approach of tuning the nucleation and growth rates with in situ-generated Sn–thiolate complexes might have a more general impact due to the availability of various metal–thiolate complexes, possibly resulting in polyhedral NCs of a wide variety of metal–sulfide compositions.

Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives

“…[148,181] However, the presence of cations can also influence the shape of the NC. [182] For example Chen et al [183] demonstrated a morphological evolution of the Cu 31 S 16 nanodisks to tetradecahedra due to the Sn 4+ -directed modification of the vertical crystal planes of the copper sulfide disk seeds. This leads to the preferential deposition of the copper and sulfur source on the vertical crystal planes, favoring the formation of the tetradecahedra.…”

Enhancement of Hydrogen Productions by Accelerating Electron-Transfers of Sulfur Defects in the CuS@CuGaS2 Heterojunction Photocatalysts

“…Copper sulfide (Cu 2−x S, 0< x < 1), a non-toxic and conductive chalcogen compound, has been continuously noted for its excellent photoelectric behavior, potential thermal/electrical properties, and unique biomedical properties for decades, and much extensive research on Cu 2−x S micro/nano structures is still being actively conducted. In particular, micro/nanostructured Cu 2−x S with well-controlled shapes, sizes, structures and compositions have already been applied as photocatalytic materials [1], energy conversion materials [2], biosensing materials [3], and bioimaging materials [4] and have shown reasonable results. However, comprehensive reviews of the Cu 2−x S structure in-depth in applications are still lacking.…”

Switching between Plasmonic and Fluorescent Copper Sulfide Nanocrystals

“…The easily tunable crystal structure of Cu 2– x S nanocrystals results in a wide variety of sizes and shapes attainable for Cu 2– x S nanocrystals by a proper choice of reaction conditions during colloidal synthesis. 12 , 13 Furthermore, depending on the size and shape of the Cu 2– x S nanocrystals and the Cu to S ratio, Cu 2– x S nanocrystals possess highly tunable localized surface plasmon resonances (LSPR) in the near-infrared (NIR) spectral region. 6 , 14 − 16 The LSPR in copper chalcogenide nanomaterials originates from excess holes in the top of the valence band, 6 , 15 , 17 which are compensated by Cu + deficiencies in the lattice.…”