Effects of Copper Precursor Reactivity on the Shape and Phase of Copper Sulfide Nanocrystals

Abstract

Controlling the crystal structure and shape and/or faceting of colloidal nanocrystals during growth through easily variable reaction parameters is highly desirable. The choice of precursors is one such parameter that can significantly impact achievable shapes and phases. Here, we examine how different Cu precursors in the synthesis of colloidal copper sulfide nanocrystals affect the resulting shape and crystal phase. An observed decreasing aspect ratio in one-dimensional nanorods (eventually transitioning to two-dimensional nanodisks) is consistent with the expected effects of decreasing Cu precursor reactivity. Nanorods are predominantly chalcocite at the early stages of growth, but a phase transition to djurleite occurs and is accompanied by a change in tip faceting upon further growth. In contrast, nanodisks appear in the djurleite phase early on and remain so upon continued growth. Localized surface plasmon resonance in various shapes of nanocrystals achieved is enhanced with chemical oxidation, and the near-field enhancement is also simulated.

Sulfur Precursor Reactivity Affecting the Crystal Phase and Morphology of Cu2−xS Nanoparticles

“…Shim et al. reported the preparation of Cu 2− x S NPs with different morphologies including sharp‐tipped/flat‐end NRs, hexagonal prisms/NDs by variation of copper precursor reactivity [69] . Our previous report showed that by tuning the amount of sulfur precursor and reaction temperature, roxbyite Cu 1.8 S triangular nanoplates were synthesized [70] .…”

“…Shim et al reported the preparation of Cu 2Àx SN Ps with differentm orphologies including sharp-tipped/flat-end NRs, hexagonal prisms/NDs by variation of copper precursor reactivity. [69] Our previous report showed that by tuning the amount of sulfur precursor and reaction temperature, roxbyiteC u 1.8 St riangularn anoplates were synthesized. [70] Moreover,C u 2 ZnSnS 4 ,C uInS 2 ,a nd Cu 2Àx SN Rs were obtained by introductiono fb ranched t-DDT as the sulfur source.E asy thermal decompositiona nd preferentialg rowth of NP along as pecial direction endow t-DDT with the capability of NR formation.…”

Plasmonic Cu2−xS nanoparticles: a brief introduction of optical properties and applications

“…Furthermore, not only the NRs, but also the hexagonal NDs as well as prisms does not show any morphology related plasmon oscillation mode. 77 As aforementioned, according to eqn (2) and ( 4)-( 7) in Section 2.3, the hole density for the singular LSPR peak in the ND can be determined. In the case of Cu 2Àx S NR with semi-axis a 4 b = c, the determination of hole density is similar with that of Cu 2Àx S ND.…”

Metal Cation Valency Dependence in Morphology Evolution of Cu2−xS Nanodisk Seeds and Their Pseudomorphic Cation Exchanges

“…For instance, by tuning of reaction temperature, reaction time, or the amount of reactant, CuTe nanotubes, nanoplates, and nanorods were prepared [36] . Another approach is a variation of copper and sulfur precursor reactivity, that is, Cu 2− x S nanorods, sharp‐tipped/flat‐end hexagonal prisms as well as nanodisks were prepared by selective utilization of copper and sulfur sources [37, 38] . More recently, it has been found that foreign metal cations, such as Al 3+ and Cd 2+ /Zn 2+ , can direct the morphology evolution of the Cu 2− x E NPs [39, 40] .…”