Browse
Submit Data
Databases
API
Help

Dataset Information

26 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions.

ABSTRACT: We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sulfide (Cu2-xSeyS1-y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2-xSeyS1-y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV-vis-NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

SUBMITTER: Lesnyak V

PROVIDER: S-EPMC4147956 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals.

Project description:We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn(2+) and Cd(2+)) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu(2-x)Se) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core-shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu(+) ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu(2-x)Se samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature.

| S-EPMC4521286 | biostudies-literature

Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

Project description:Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum.

| S-EPMC5736242 | biostudies-literature

Sn cation valency dependence in cation exchange reactions involving Cu(2-x)Se nanocrystals.

Project description:We studied cation exchange reactions in colloidal Cu(2-x)Se nanocrystals (NCs) involving the replacement of Cu(+) cations with either Sn(2+) or Sn(4+) cations. This is a model system in several aspects: first, the +2 and +4 oxidation states for tin are relatively stable; in addition, the phase of the Cu(2-x)Se NCs remains cubic regardless of the degree of copper deficiency (that is, "x") in the NC lattice. Also, Sn(4+) ions are comparable in size to the Cu(+) ions, while Sn(2+) ones are much larger. We show here that the valency of the entering Sn ions dictates the structure and composition not only of the final products but also of the intermediate steps of the exchange. When Sn(4+) cations are used, alloyed Cu(2-4y)Sn(y)Se NCs (with y ≤ 0.33) are formed as intermediates, with almost no distortion of the anion framework, apart from a small contraction. In this exchange reaction the final stoichiometry of the NCs cannot go beyond Cu0.66Sn0.33Se (that is Cu2SnSe3), as any further replacement of Cu(+) cations with Sn(4+) cations would require a drastic reorganization of the anion framework, which is not possible at the reaction conditions of the experiments. When instead Sn(2+) cations are employed, SnSe NCs are formed, mostly in the orthorhombic phase, with significant, albeit not drastic, distortion of the anion framework. Intermediate steps in this exchange reaction are represented by Janus-type Cu(2-x)Se/SnSe heterostructures, with no Cu-Sn-Se alloys.

| S-EPMC4244862 | biostudies-literature

Bright and compact alloyed quantum dots with broadly tunable near-infrared absorption and fluorescence spectra through mercury cation exchange.

Project description:We report a new strategy based on mercury cation exchange in nonpolar solvents to prepare bright and compact alloyed quantum dots (QDs) (Hg(x)Cd(1-x)E, where E = Te, Se, or S) with equalized particle size and broadly tunable absorption and fluorescence emission in the near-infrared. The main rationale is that cubic CdE and HgE have nearly identical lattice constants but very different band gap energies and electron/hole masses. Thus, replacement of Cd(2+) by Hg(2+) in CdTe nanocrystals does not change the particle size, but it greatly alters the band gap energy. After capping with a multilayer shell and solubilization with a multidentate ligand, this class of cation-exchanged QDs are compact (6.5 nm nanocrystal size and 10 nm hydrodynamic diameter) and very bright (60-80% quantum yield), with narrow and symmetric fluorescence spectra tunable across the wavelength range from 700 to 1150 nm.

| S-EPMC3102112 | biostudies-literature

Tuning infrared plasmon resonances in doped metal-oxide nanocrystals through cation-exchange reactions.

Project description:Metal-oxide nanocrystals doped with aliovalent atoms can exhibit tunable infrared localized surface plasmon resonances (LSPRs). Yet, the range of dopant types and concentrations remains limited for many metal-oxide hosts, largely because of the difficulty in establishing reaction kinetics that favors dopant incorporation by using the co-thermolysis method. Here we develop cation-exchange reactions to introduce p-type dopants (Cu+, Ag+, etc.) into n-type metal-oxide nanocrystals, producing programmable LSPR redshifts due to dopant compensation. We further demonstrate that enhanced n-type doping can be realized via sequential cation-exchange reactions mediated by the Cu+ ions. Cation-exchange transformations add a new dimension to the design of plasmonic nanocrystals, allowing preformed nanocrystals to be used as templates to create compositionally diverse nanocrystals with well-defined LSPR characteristics. The ability to tailor the doping profile postsynthetically opens the door to a multitude of opportunities to deepen our understanding of the relationship between local structure and LSPR properties.

| S-EPMC6437201 | biostudies-literature

Copper Chalcogenide-Copper Tetrahedrite Composites-A New Concept for Stable Thermoelectric Materials Based on the Chalcogenide System.

Project description:For the first time, an alternative way of improving the stability of Cu-based thermoelectric materials is proposed, with the investigation of two different copper chalcogenide-copper tetrahedrite composites, rich in sulfur and selenium anions, respectively. Based on the preliminary DFT results, which indicate the instability of Sb-doped copper chalcogenide, the Cu1.97S-Cu12Sb4S13 and Cu2-xSe-Cu3SbSe3 composites are obtained using melt-solidification techniques, with the tetrahedrite phase concentration varying from 1 to 10 wt.%. Room temperature structural analysis (XRD, SEM) indicates the two-phase structure of the materials, with ternary phase precipitates embed within the copper chalcogenide matrix. The proposed solution allows for successful blocking of excessive Cu migration, with stable electrical conductivity and Seebeck coefficient values over subsequent thermal cycles. The materials exhibit a p-type, semimetallic character with high stability, represented by a near-constant power factor (PF)-temperature dependences between individual cycles. Finally, the thermoelectric figure-of-merit ZT parameter reaches about 0.26 (623 K) for the Cu1.97S-Cu12Sb4S13 system, in which case increasing content of tetrahedrite is a beneficial effect, and about 0.44 (623 K) for the Cu2-xSe-Cu3SbSe3 system, where increasing the content of Cu3SbSe3 negatively influences the thermoelectric performance.

| S-EPMC8157852 | biostudies-literature

Mechanistic insight into copper cation exchange in cadmium selenide semiconductor nanocrystals using X-ray absorption spectroscopy.

Project description:In terms of producing new advances in sustainable nanomaterials, cation exchange (CE) of post-processed colloidal nanocrystals (NCs) has opened new avenues towards producing non-toxic energy materials via simple chemical techniques. The main processes governing CE can be explained by considering hard/soft acid/base theory, but the detailed mechanism of CE, however, has been debated and has been attributed to both diffusion and vacancy processes. In this work, we have performed in situ x-ray absorption spectroscopy to further understand the mechanism of the CE of copper in solution phase CdSe NCs. The x-ray data indicates clear isosbestic points, suggestive of cooperative behavior as previously observed via optical spectroscopy. Examination of the extended x-ray absorption fine structure data points to the observation of interstitial impurities during the initial stages of CE, suggesting the diffusion process is the fundamental mechanism of CE in this system.

| S-EPMC7815718 | biostudies-literature

Role of the Crystal Structure in Cation Exchange Reactions Involving Colloidal Cu<sub>2</sub>Se Nanocrystals.

Project description:Stoichiometric Cu2Se nanocrystals were synthesized in either cubic or hexagonal (metastable) crystal structures and used as the host material in cation exchange reactions with Pb2+ ions. Even if the final product of the exchange, in both cases, was rock-salt PbSe nanocrystals, we show here that the crystal structure of the starting nanocrystals has a strong influence on the exchange pathway. The exposure of cubic Cu2Se nanocrystals to Pb2+ cations led to the initial formation of PbSe unselectively on the overall surface of the host nanocrystals, generating Cu2Se@PbSe core@shell nanoheterostructures. The formation of such intermediates was attributed to the low diffusivity of Pb2+ ions inside the host lattice and to the absence of preferred entry points in cubic Cu2Se. On the other hand, in hexagonal Cu2Se nanocrystals, the entrance of Pb2+ ions generated PbSe stripes "sandwiched" in between hexagonal Cu2Se domains. These peculiar heterostructures formed as a consequence of the preferential diffusion of Pb2+ ions through specific (a, b) planes of the hexagonal Cu2Se structure, which are characterized by almost empty octahedral sites. Our findings suggest that the morphology of the nanoheterostructures, formed upon partial cation exchange reactions, is intimately connected not only to the NC host material, but also to its crystal structure.

| S-EPMC6105078 | biostudies-literature

Microsomal palmitoyl coenzyme A synthetase from rat liver. Partial and exchange reactions.

Project description:The partial and exchange reactions of long-chain fatty acid activation were determined by using purified microsomal long-chain fatty acyl-CoA synthetase (EC 6.2.1.3). No significant ATP formation from palmitoyl-AMP and PP(i), nor palmitoyl-AMP-dependent CoA disappearance could be demonstrated. Similarly, no palmitate-dependent [(32)P(2)]PP(i)-ATP exchange was catalysed by the pure enzyme. The above partial and exchange reactions were, however, catalysed by the parent microsomal fraction at a rate similar to that of the overall reaction. The implications of these results are discussed.

| S-EPMC1174268 | biostudies-other

Metastable CdTe@HgTe Core@Shell Nanostructures Obtained by Partial Cation Exchange Evolve into Sintered CdTe Films Upon Annealing.

Project description:Partial Hg2+ → Cd2+ cation exchange (CE) reactions were exploited to transform colloidal CdTe nanocrystals (NCs, 4-6 nm in size) into CdTe@HgTe core@shell nanostructures. This was achieved by working under a slow CE rate, which limited the exchange to the surface of the CdTe NCs. In such nanostructures, when annealed at mild temperatures (as low as 200 °C), the HgTe shell sublimated or melted and the NCs sintered together, with the concomitant desorption of their surface ligands. At the end of this process, the annealed samples consisted of ligand-free CdTe sintered films containing an amount of Hg2+ that was much lower than that of the starting CdTe@HgTe NCs. For example, the CdTe@HgTe NCs that initially contained 10% of Hg2+, after being annealed at 200 °C were transformed to CdTe sintered films containing only traces of Hg2+ (less than 1%). This procedure was then used to fabricate a proof-of-concept CdTe-based photodetector exhibiting a photoresponse of up to 0.5 A/W and a detectivity of ca. 9 × 104 Jones under blue light illumination. Our strategy suggests that CE protocols might be exploited to lower the overall costs of production of CdTe thin films employed in photovoltaic technology, which are currently fabricated at high temperatures (above 350 °C), using post-process ligand-stripping steps.

| S-EPMC8016170 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data