Transformation from Cu_2–xS Nanodisks to Cu_2–xS@CuInS₂ Heteronanodisks via Cation Exchange

Abstract

Cationic-exchange methods allow for the fabrication of metastable phases or shapes, which are impossible to obtain with conventional synthetic colloidal methods. Here, we present the systematic fabrication of heteronanostructured (HNS) Cu 2−x S@CuInS 2 nanodisks via a cationic-exchange reaction between Cu and In atoms. The indium−trioctylphosphine complex favorably attacks the lateral (16 0 0) plane of the roxbyite Cu 2−x S hexagon. We explain the phenomena by estimating the formation energy of vacancies and the heat of reaction required to exchange three Cu atoms with an In atom via density functional theory calculations. In an experiment, a decrease in the amount of trioctylphosphine surfactant slows the reaction rate and allows for the formation of a lateral heterojunction structure of nanoplatelets. We analyze the exact structures of these materials using scanning transmission electron microscopy−energy dispersive X-ray spectroscopy and high-resolution transmission electron microscopy. Moreover, we demonstrate that our heteronanodisk can be an intermediate for different HNS materials; for example, adding gold precursors to a Cu 2−x S@CuInS 2 nanodisk results in a AuS@CuInS 2 nanodisk via an additional cationic reaction between Cu ions and Au ions.

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

“…This then leads to the formation of heteronanostructured Cu 2−x S/CuInS 2 nanodisks, with topology of chemical composition as shown in Figure 33e. [355] In a different approach, CuInSe 2 nanoparticles were synthesized by a redox induced phase transformation of the copper selenide nanoparticle template upon addition of elemental indium. [351] The elegance of this strategy stands on the use of a sacrificial template of copper diselenide CuSe 2 that has a chemical and structural similarity to that of CuInSe 2 .…”

“…Each color spot represents an element of blue -copper, green -indium, red -sulfur. Adapted with permission from ref[355] Copyright 2016 American Chemical Society.…”

Semiconductor Nanocrystal Engineering by Applying Thiol‐ and Solvent‐Coordinated Cation Exchange Kinetics

“…[8] Despite the progress made with regards to composition and crystallinity control, [9] efficient aliovalent doping and highly curved heterostructuring to metal in the nanoscale are critical and still remain abig challenge.Cation exchange conversion of CSNCs has been exploited as ap otential crystal engineering strategy for precisely controlling the morphology,c omposition and crystallinity. [1][2][3][4] The groups of Alivisatos,M anna, Schaak, Zhang,K im, and Pradhan [7,8,[10][11][12][13][14][15][16] have taken such advantages to synthesize CSNCs.Wehave reported that tertiary phosphines (R 3 P) with different Rg roups could initialize cation exchange reactions to precisely tune the targeted CdX (X = S, Se etc. )N Cs crystallization, dopant concentration, and hetero-interface to Au NCs.…”

“…)N Cs crystallization, dopant concentration, and hetero-interface to Au NCs. [5,9a, 17] While cation exchange by utilizing phosphine ligands has gone through astonishing developments, [5,[10][11][12][13][14][15][16] it is anticipated that the chemistry of ligand-coordinated cation exchange reactions will enable new nanocrystal engineering.I np articular, so far, efficient doping and heterointerface control in the environmentally friendly CSNCs,s uch as ZnS with intrinsic defects,h as not been achieved. [5,9a, 17] While cation exchange by utilizing phosphine ligands has gone through astonishing developments, [5,[10][11][12][13][14][15][16] it is anticipated that the chemistry of ligand-coordinated cation exchange reactions will enable new nanocrystal engineering.I np articular, so far, efficient doping and heterointerface control in the environmentally friendly CSNCs,s uch as ZnS with intrinsic defects,h as not been achieved.…”

“…[5,17] In particular,t he stable deep-position Ag + or Cu + doping in CdX CSNCs has been achieved by reverse cation exchange between Ag 2 X, Cu 2 X, and phosphine-coordinated Cd 2+ ions,thus leading to the unprecedented discovery of an excitonic pathway to photoinduced magnetism in our Ag-doped CdSe NCs. [5,9a, 17] While cation exchange by utilizing phosphine ligands has gone through astonishing developments, [5,[10][11][12][13][14][15][16] it is anticipated that the chemistry of ligand-coordinated cation exchange reactions will enable new nanocrystal engineering.I np articular, so far, efficient doping and heterointerface control in the environmentally friendly CSNCs,s uch as ZnS with intrinsic defects,h as not been achieved. Furthermore,t he understanding of the fundamental chemistry of cation exchange is expected to create more general and constructive approaches towards versatile nanoscale building blocks and the desired multi-functionality.…”