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Selective cation exchange in the core region of Cu2-xSe/Cu2-xS core/shell nanocrystals.

Miszta K, Gariano G, Brescia R, Marras S, De Donato F, Ghosh S, De Trizio L, Manna L - J. Am. Chem. Soc. (2015)

Bottom Line: We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT) , via Morego, 30, 16163 Genova, Italy.

ABSTRACT
We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), 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.

No MeSH data available.


CE in a mixed populationof Cu2–xS and Cu2–xSe NCs with Ag+ and Hg2+ ions.HAADF-STEM images of groups ofcopper sulfide and copper selenide NCs exposed to (a) Ag+ or (b) Hg2+ ions with the corresponding STEM-EDS elementalmaps. The scale bar in each image is 20 nm.
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fig5: CE in a mixed populationof Cu2–xS and Cu2–xSe NCs with Ag+ and Hg2+ ions.HAADF-STEM images of groups ofcopper sulfide and copper selenide NCs exposed to (a) Ag+ or (b) Hg2+ ions with the corresponding STEM-EDS elementalmaps. The scale bar in each image is 20 nm.

Mentions: In yet another control experiment,a mixture of Cu2–xS and Cu2–xSeNCs, prepared by standard direct synthesis protocols and not via CE(see SI for details), was exposed eitherto Ag+ or to Hg2+ ions. Here too, the experimentswere run with Ag/Cu or Hg/Cu feed ratios that were insufficient toachieve a complete replacement of the copper ions, in order to triggercompetition between the two different types of NCs toward CE (see SI for experimental details). In analogy withthe experiments discussed above, CE selectively affected the Cu2–xSe NCs rather than the Cu2–xS ones (see Figure 5). These experiments rule out any potential influenceof the preparatory history of the copper chalcogenide NCs (i.e., whetherthey were synthesized directly or they were prepared instead by CE)on their reactivity toward the guest cations.


Selective cation exchange in the core region of Cu2-xSe/Cu2-xS core/shell nanocrystals.

Miszta K, Gariano G, Brescia R, Marras S, De Donato F, Ghosh S, De Trizio L, Manna L - J. Am. Chem. Soc. (2015)

CE in a mixed populationof Cu2–xS and Cu2–xSe NCs with Ag+ and Hg2+ ions.HAADF-STEM images of groups ofcopper sulfide and copper selenide NCs exposed to (a) Ag+ or (b) Hg2+ ions with the corresponding STEM-EDS elementalmaps. The scale bar in each image is 20 nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591528&req=5

fig5: CE in a mixed populationof Cu2–xS and Cu2–xSe NCs with Ag+ and Hg2+ ions.HAADF-STEM images of groups ofcopper sulfide and copper selenide NCs exposed to (a) Ag+ or (b) Hg2+ ions with the corresponding STEM-EDS elementalmaps. The scale bar in each image is 20 nm.
Mentions: In yet another control experiment,a mixture of Cu2–xS and Cu2–xSeNCs, prepared by standard direct synthesis protocols and not via CE(see SI for details), was exposed eitherto Ag+ or to Hg2+ ions. Here too, the experimentswere run with Ag/Cu or Hg/Cu feed ratios that were insufficient toachieve a complete replacement of the copper ions, in order to triggercompetition between the two different types of NCs toward CE (see SI for experimental details). In analogy withthe experiments discussed above, CE selectively affected the Cu2–xSe NCs rather than the Cu2–xS ones (see Figure 5). These experiments rule out any potential influenceof the preparatory history of the copper chalcogenide NCs (i.e., whetherthey were synthesized directly or they were prepared instead by CE)on their reactivity toward the guest cations.

Bottom Line: We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT) , via Morego, 30, 16163 Genova, Italy.

ABSTRACT
We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), 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.

No MeSH data available.