Selective Cation Exchange in the Core Region of Cu_2–xSe/Cu_2–xS Core/Shell Nanocrystals

Abstract

We studied cation exchange (CE) in core/shell Cu2–xSe/Cu2–xS nanorods with two cations, Ag+ and Hg2+, which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature. At the initial stage of the reaction, the guest ions diffused through the Cu2–xS shell and reached the Cu2–xSe core, replacing first Cu+ ions within the latter region. These experiments prove that CE in copper chalcogenide NCs is facilitated by the high diffusivity of guest cations in the lattice, such that they can probe the whole host structure and identify the preferred regions where to initiate the exchange. For both guest ions, CE is thermodynamically driven as it aims for the formation of the chalcogen phase characterized by the lower solubility under the specific reaction conditions.

Reversible cation exchange on macroscopic CdSe/CdS and CdS nanorod based gel networks

“…Established by recent studies published in the literature for cation exchange reactions at single nanocrystals, the copper chalcogenide phase was used as an intermediate for further cation exchange reactions. 31,[39][40][41] To show the reversibility of the cation exchange, the copper chalcogenide acetogels were also exchanged back to CdSe/CdS NR and CdS NR acetogels and heated for several weeks to recover their original fluorescence properties. 39 Microscopic characterization techniques (SEM and TEM) were performed in order to analyse the morphological changes in the aerogel structures due to the cation exchange reactions.…”

“…1,3,29 In the recent past, different working groups investigated cation exchange reactions on nanocrystals with different shapes and material composition. [30][31][32][33][34][35] Due to the short diffusion path of the cations within the nanoparticle crystal, even cation exchange reactions which are unknown (or extremely slow) on the bulk scale can occur. In nanoparticle systems, the cation exchange process can take place in the millisecond regime.…”

Pd-dispersed CuS hetero-nanoplates for selective hydrogenation of phenylacetylene

“…5(c). Rather than the further cation exchange occurring to the entire CuS nanoplates, the dark-contrast region emerged on the edges of nanoplates and from which it proceeded to the remaining volume, so that both the interfacial energy and the elastic strain between the two different domains are minimized [35,36]. The major reaction steps in the formation of Pd-dispersed CuS nanoplates (Fig.…”

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

“…Crystal engineering of colloidal semiconductor nanocrystals (CSNCs) to control electronic impurities doping and the hetero-interface to metal nanoparticles are critical for their real optoelectronics and photonic applications, [1,2] such as solid-state lighting, [3] lasing, [4] photovoltaics, [5,6] photodetection, [7] and sensors. [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.…”

“…[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.…”