Identifying short surface ligands on metal phosphide quantum dots

Baquero, Edwin A.; Ojo, Wilfried-Solo; Coppel, Yannick; Chaudret, Bruno; Urbaszek, B.; Nayral, Céline; Delpech, Fabien

doi:10.1039/c6cp03564g

Cited by 21 publications

(29 citation statements)

References 55 publications

(47 reference statements)

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“…As we have recently demonstrated, this 31 PO 4 phosphate signal results from the overlap of the resonances of several phosphate species: O=P(OM) x (OH) 3-x (M=In, x=1-3). 22 For the example shown in Figure 1b, this yielded only 2% of oxidized phosphorous. This result confirms previous studies that showed that the aminophosphinebased protocol allows oxide-free InP QDs to be made, thanks to the use of water-and carboxylate-free precursors.…”

Section: Resultsmentioning

confidence: 99%

“…A more detailed description of this interface results from a 1 H Forth and Back Cross Polarization (FBCP) MAS NMR experiment. 22 Such a measurement relies on the transfer of polarization from H atoms that are part of the stabilizing ligand to the P atoms at the QD and back to the closest H atom. In this way, we can detect P-OH species that are usually invisible with the classical 1 H MAS NMR techniques.…”

Section: Resultsmentioning

confidence: 99%

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Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

et al. 2018

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Indium phosphide colloidal quantum dots (QDs) are emerging as an efficient cadmium-free alternative for optoelectronic applications. Recently, syntheses based on easy-to-implement aminophosphine precursors have been developed. We show by solid-state nuclear magnetic resonance spectroscopy that this new approach allows oxide-free indium phosphide core or core/shell quantum dots to be made. Importantly, the oxide-free core/shell interface does not help in achieving higher luminescence efficiencies. We demonstrate that in the case of InP/ZnS and InP/ZnSe QDs, a more pronounced oxidation concurs with a higher photoluminescence efficiency. This study suggests that a II–VI shell on a III–V core generates an interface prone to defects. The most efficient InP/ZnS or InP/ZnSe QDs are therefore made with an oxide buffer layer between the core and the shell: it passivates these interface defects but also results in a somewhat broader emission line width.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

et al. 2018

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“…Although HETCOR is powerful, the experiment is also time‐consuming. Recently, Delpech and co‐workers proposed the use of a Forth and Back CP experiment (FBCP), in which polarization is transferred from the hydrogen to the phosphorus atoms of an NC and back to the hydrogen atoms . Thus, it was possible to probe the hydrogen atoms selectively, on and close to the phosphorus atom at the NC surface.…”

Section: Resultsmentioning

confidence: 99%

“…Recently,D elpech and co-workersp roposed the use of aF orth and Back CP experiment (FBCP), in which polarization is transferred from the hydrogen to the phosphorus atoms of an NC and back to the hydrogen atoms. [29] Thus,i tw as possible to probe the hydrogen atoms selectively,o na nd close to the phosphorus atom at the NC surface. In our case of HfO 2 NCs, the inorganic core does not contain any abundant NMR-sensitive nucleus, hampering the technique.…”

Section: Generalization To Hfo 2 Ncsmentioning

confidence: 99%

Insights into the Ligand Shell, Coordination Mode, and Reactivity of Carboxylic Acid Capped Metal Oxide Nanocrystals

et al. 2016

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A detailed knowledge of surface chemistry is necessary to bridge the gap between nanocrystal synthesis and applications. Although it has been proposed that carboxylic acids bind to metal oxides in a dissociative NC(X)2 binding motif, this surface chemistry was inferred from indirect evidence on HfO2 nanocrystals (NCs). Here, a more detailed picture of the coordination mode of carboxylate ligands on HfO2 and ZrO2 NC surfaces is shown by direct observation through solid‐state NMR techniques. Surface‐adsorbed protons are clearly distinguished and two coordination modes of the carboxylic acid are noted: chelating and bridging. It is also found that secondary ligands penetrate the ligand shell and have the same orientation with respect to the surface as the primary ligands, indicating that the ionic or hydrogen‐bonding interactions with the surface are more important than the van der Waals interactions with neighboring ligands. During ligand exchange with amines, the chelating carboxylate is removed preferentially. Finally, it is shown that the HfO2 and ZrO2 NCs catalyze imine formation from acetone and oleylamine. Together with the previously reported catalytic activity of HfO2, these results put colloidal metal oxide nanocrystals squarely in the focus of catalysis research.

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“…Other types of ligands have also been studied on nanoparticles . Gullion and co‐workers used 13 C– 15 N REDOR to determine the adsorption configuration of L ‐cysteine on gold nanoparticles.…”

Section: Interfaces In Nanocrystals and Quantum Dotsmentioning

confidence: 99%

Understanding Surface and Interfacial Chemistry in Functional Nanomaterials via Solid‐State NMR

et al. 2017

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Surface and interfacial chemistry is of fundamental importance in functional nanomaterials applied in catalysis, energy storage and conversion, medicine, and other nanotechnologies. It has been a perpetual challenge for the scientific community to get an accurate and comprehensive picture of the structures, dynamics, and interactions at interfaces. Here, some recent examples in the major disciplines of nanomaterials are selected (e.g., nanoporous materials, battery materials, nanocrystals and quantum dots, supramolecular assemblies, drug-delivery systems, ionomers, and graphite oxides) and it is shown how interfacial chemistry can be addressed through the perspective of solid-state NMR characterization techniques.

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Identifying short surface ligands on metal phosphide quantum dots

Abstract: The control and understanding of the chemical and physical properties of quantum dots (QDs) demands detailed surface characterization.

Cited by 21 publications

References 55 publications

Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

Insights into the Ligand Shell, Coordination Mode, and Reactivity of Carboxylic Acid Capped Metal Oxide Nanocrystals

Understanding Surface and Interfacial Chemistry in Functional Nanomaterials via Solid‐State NMR

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