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Verma E, Choi MH, Kar N, Baker LA, Skrabalak SE. Bridging colloidal and electrochemical syntheses of metal nanocrystals with seeded electrodeposition for tracking single nanocrystal growth. NANOSCALE 2024; 16:8002-8012. [PMID: 38535987 DOI: 10.1039/d4nr00202d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Metal nanocrystals (NCs) produced by colloidal synthesis have a variety of structural features, such as different planes, edges, and defects. Even from the best colloidal syntheses, these characteristics are distributed differently in each NC. This inherent heterogeneity can play a significant role in the properties displayed by NCs. This manuscript reports the use of electrochemistry to synthesize Au NCs in a system evaluated to track individual NC growth trajectories as a first step toward rapid identification of NCs with different structural features. Au nanocubes were prepared colloidally and deposited onto a glassy carbon electrode using either electrospray or an airbrush, resulting in well-spaced Au nanocubes. The Au nanocubes then served as seeds as gold salt was reduced to deposit metal at constant potential. Deposition at constant potential facilitates overgrowth on the Au nanocubes to achieve new NC shapes. The effects of applied potential, deposition time, precursor concentration, and capping agents on NC shape evolution were studied. The outcomes are correlated to results from traditional colloidal syntheses, providing a bridge between the two synthetic strategies. Moreover, scanning electron microscopy was used to image the same NCs before and after deposition, linking individual seed features to differences in deposition. This ability is anticipated to enable tracking of individual growth trajectories of NCs to elucidate sources of heterogeneity in NC syntheses.
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Affiliation(s)
- Ekta Verma
- Department of Chemistry, Indiana University - Bloomington, Bloomington, Indiana, 47405, USA.
| | - Myung-Hoon Choi
- Department of Chemistry, Texas A&M University, College Station, Texas, 77843, USA
| | - Nabojit Kar
- Department of Chemistry, Indiana University - Bloomington, Bloomington, Indiana, 47405, USA.
| | - Lane A Baker
- Department of Chemistry, Texas A&M University, College Station, Texas, 77843, USA
| | - Sara E Skrabalak
- Department of Chemistry, Indiana University - Bloomington, Bloomington, Indiana, 47405, USA.
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2
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Narayanan T. Recent advances in synchrotron scattering methods for probing the structure and dynamics of colloids. Adv Colloid Interface Sci 2024; 325:103114. [PMID: 38452431 DOI: 10.1016/j.cis.2024.103114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 02/07/2024] [Accepted: 02/14/2024] [Indexed: 03/09/2024]
Abstract
Recent progress in synchrotron based X-ray scattering methods applied to colloid science is reviewed. An important figure of merit of these techniques is that they enable in situ investigations of colloidal systems under the desired thermophysical and rheological conditions. An ensemble averaged simultaneous structural and dynamical information can be derived albeit in reciprocal space. Significant improvements in X-ray source brilliance and advances in detector technology have overcome some of the limitations in the past. Notably coherent X-ray scattering techniques have become more competitive and they provide complementary information to laboratory based real space methods. For a system with sufficient scattering contrast, size ranges from nm to several μm and time scales down to μs are now amenable to X-ray scattering investigations. A wide variety of sample environments can be combined with scattering experiments further enriching the science that could be pursued by means of advanced X-ray scattering instruments. Some of these recent progresses are illustrated via representative examples. To derive quantitative information from the scattering data, rigorous data analysis or modeling is required. Development of powerful computational tools including the use of artificial intelligence have become the emerging trend.
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3
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Saenz N, Hamachi LS, Wolock A, Goodge BH, Kuntzmann A, Dubertret B, Billinge I, Kourkoutis LF, Muller DA, Crowther AC, Owen JS. Synthesis of graded CdS 1-xSe x nanoplatelet alloys and heterostructures from pairs of chalcogenoureas with tailored conversion reactivity. Chem Sci 2023; 14:12345-12354. [PMID: 37969574 PMCID: PMC10631235 DOI: 10.1039/d3sc03384h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/13/2023] [Indexed: 11/17/2023] Open
Abstract
A mixture of N,N,N'-trisubstituted thiourea and cyclic N,N,N',N'-tetrasubstituted selenourea precursors were used to synthesize three monolayer thick CdS1-xSex nanoplatelets in a single synthetic step. The microstructure of the nanoplatelets could be tuned from homogeneous alloys, to graded alloys to core/crown heterostructures depending on the relative conversion reactivity of the sulfur and selenium precursors. UV-visible absorption and photoluminescence spectroscopy and scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) images demonstrate that the elemental distribution is governed by the relative precursor conversion kinetics. Slow conversion kinetics produced nanoplatelets with larger lateral dimensions, behavior that is characteristic of precursor conversion limited growth kinetics. Across a 10-fold range of reactivity, CdS nanoplatelets have 4× smaller lateral dimensions than CdSe nanoplatelets grown under identical conversion kinetics. The difference in size is consistent with a rate of CdSe growth that is 4× greater than the rate of CdS. The influence of the relative sulfide and selenide growth rates, the duration of the nucleation phase, and the solute composition on the nanoplatelet microstructure are discussed.
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Affiliation(s)
- Natalie Saenz
- Department of Chemistry, Columbia University New York NY USA
| | | | - Anna Wolock
- Department of Chemistry, Barnard College, Columbia University New York NY USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
| | - Alexis Kuntzmann
- Ecole Supérieure de Physique et de Chimie Industrielle Paris France
| | - Benoit Dubertret
- Ecole Supérieure de Physique et de Chimie Industrielle Paris France
| | - Isabel Billinge
- Department of Chemistry, Columbia University New York NY USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University Ithaca NY 14853 USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University Ithaca NY 14853 USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University Ithaca NY 14853 USA
| | - Andrew C Crowther
- Department of Chemistry, Barnard College, Columbia University New York NY USA
| | - Jonathan S Owen
- Department of Chemistry, Columbia University New York NY USA
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4
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Jia Z, Dai Y, Shao H, Xu J, Meng Q, Qiao J. Room-Temperature, Multigram-Scale Synthesis and Conversion Mechanism of Highly Luminescent Lead Sulfide Quantum Dots. J Phys Chem Lett 2023; 14:8129-8137. [PMID: 37669406 DOI: 10.1021/acs.jpclett.3c02005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
PbS quantum dots (QDs) are attractive near-infrared (NIR) materials, but traditional synthetic methods require inert atmosphere and/or high temperature. Herein we develop a facile, room-temperature synthetic route for in situ halide passivated PbS QDs through controllable reactions between lead halide, N,N'-diphenyl thiourea, and oleyamine (OLA) in toluene. Contrast experiments and theoretical calculations reveal that the OLA plays a bifunctional role as a mild base to initiate the formation of PbS monomers and as a dynamic ligand to control the crystallization of PbS QDs and further ligand exchange. The oleic acid-capped PbS QDs exhibit high photoluminescence quantum yields up to 45%. The scaled-up synthesis on multigram scales shows great batch-to-batch consistency. We further demonstrate high-power NIR light-emitting diodes using the PbS QDs as color converters, delivering NIR optical power of 9.2 mW at 160 mA. This work provides a simple and versatile synthetic route for high-quality PbS QDs and boosts the applications of NIR materials.
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Affiliation(s)
- Zhen Jia
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Yu Dai
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Haoyun Shao
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Jingyi Xu
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Qingyu Meng
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Juan Qiao
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
- Laboratory for Flexible Electronics Technology, Tsinghua University, Beijing 100084, P. R. China
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5
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Hasham M, Green PB, Rahman S, Villanueva FY, Imperiale CJ, Kirshenbaum MJ, Wilson MWB. The smallest PbS nanocrystals pervasively show decreased brightness, linked to surface-mediated decay on the average particle. J Chem Phys 2023; 159:074704. [PMID: 37602803 DOI: 10.1063/5.0159681] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/25/2023] [Indexed: 08/22/2023] Open
Abstract
PbS semiconductor nanocrystals (NCs) have been heavily explored for infrared optoelectronics but can exhibit visible-wavelength quantum-confined optical gaps when sufficiently small (⌀ = 1.8-2.7 nm). However, small PbS NCs traditionally exhibited very broad ensemble absorption linewidths, attributed to poor size-heterogeneity. Here, harnessing recent synthetic advances, we report photophysical measurements on PbS ensembles that span this underexplored size range. We observe that the smallest PbS NCs pervasively exhibit lower brightness and anomalously accelerated photoluminescence decays-relative to the idealized photophysical models that successfully describe larger NCs. We find that effects of residual ensemble size-heterogeneity are insufficient to explain our observations, so we explore plausible processes that are intrinsic to individual nanocrystals. Notably, the anomalous decay kinetics unfold, surprisingly, over hundreds-of-nanosecond timescales. These are poorly matched to effects of direct carrier trapping or fine-structure thermalization but are consistent with non-radiative recombination linked to a dynamic surface. Thus, the progressive enhancement of anomalous decay in the smallest particles supports predictions that the surface plays an outsized role in exciton-phonon coupling. We corroborate this claim by showing that the anomalous decay is significantly remedied by the installation of a rigidifying shell. Intriguingly, our measurements show that the anomalous aspect of these kinetics is insensitive to temperature between T = 298 and 77 K, offering important experimental constraint on possible mechanisms involving structural fluctuations. Thus, our findings identify and map the anomalous photoluminescence kinetics that become pervasive in the smallest PbS NCs and call for targeted experiments and theory to disentangle their origin.
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Affiliation(s)
- Minhal Hasham
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Philippe B Green
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Samihat Rahman
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | | | | | - Maxine J Kirshenbaum
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Mark W B Wilson
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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6
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Nguyen HA, Dixon G, Dou FY, Gallagher S, Gibbs S, Ladd DM, Marino E, Ondry JC, Shanahan JP, Vasileiadou ES, Barlow S, Gamelin DR, Ginger DS, Jonas DM, Kanatzidis MG, Marder SR, Morton D, Murray CB, Owen JS, Talapin DV, Toney MF, Cossairt BM. Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution. Chem Rev 2023. [PMID: 37311205 DOI: 10.1021/acs.chemrev.3c00097] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Solution-processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements for semiconductors used in these applications is a narrow photoluminescence (PL) line width. Narrow emission line widths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review, we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including "homogeneous" broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission line width for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, including an outline of promising paths forward.
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Affiliation(s)
- Hao A Nguyen
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Grant Dixon
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Florence Y Dou
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Shaun Gallagher
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Stephen Gibbs
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Dylan M Ladd
- Department of Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Emanuele Marino
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Via Archirafi 36, 90123 Palermo, Italy
| | - Justin C Ondry
- Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - James P Shanahan
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Eugenia S Vasileiadou
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephen Barlow
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - David M Jonas
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Mercouri G Kanatzidis
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Seth R Marder
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Daniel Morton
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Christopher B Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jonathan S Owen
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dmitri V Talapin
- Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Michael F Toney
- Department of Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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7
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Horani F, Sharma K, Abu-Hariri A, Lifshitz E. Colloidal Control of Branching in Metal Chalcogenide Semiconductor Nanostructures. J Phys Chem Lett 2023; 14:3794-3804. [PMID: 37052606 DOI: 10.1021/acs.jpclett.3c00285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Colloidal syntheses of metal chalcogenides yield nanostructures of various 1D, 2D, and 3D nanocrystals (NCs), including branched nanostructures (BNSs) of nanoflowers, tetrapods, octopods, nanourchins, and more. Efforts are continuously being made to understand the branching mechanism in colloidally prepared metal chalcogenides for tailor-making them into various morphologies for dedicated applications in solar cells, light-emitting diodes, stress sensor devices, and near-infrared photodetectors. The vital role of precursors and ligands has widely been recognized in directing nanocrystal morphology during the colloidal synthesis of metal chalcogenide nanostructures. Moreover, a few basic branching mechanisms in nanocrystals have also been derived from decades-long observations of branching in NCs. This Perspective (a) accounts for the mediation of branching in In2S3, PbS, MoSe2, WSe2, and WS2; (b) analyzes the underlying mechanisms; and (c) gives a future perspective toward better controlling the BNSs' morphologies and their impact on applications.
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Affiliation(s)
- Faris Horani
- Israel Schulich Faculty of Chemistry, the Solid-State Institute, the Russell Berrie Nanotechnology Institute, and the Helen Diller Quantum Information Center, Technion, Haifa 3200003, Israel
| | - Kusha Sharma
- Israel Schulich Faculty of Chemistry, the Solid-State Institute, the Russell Berrie Nanotechnology Institute, and the Helen Diller Quantum Information Center, Technion, Haifa 3200003, Israel
| | - Azhar Abu-Hariri
- Israel Schulich Faculty of Chemistry, the Solid-State Institute, the Russell Berrie Nanotechnology Institute, and the Helen Diller Quantum Information Center, Technion, Haifa 3200003, Israel
| | - Efrat Lifshitz
- Israel Schulich Faculty of Chemistry, the Solid-State Institute, the Russell Berrie Nanotechnology Institute, and the Helen Diller Quantum Information Center, Technion, Haifa 3200003, Israel
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8
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Pokratath R, Lermusiaux L, Checchia S, Mathew JP, Cooper SR, Mathiesen JK, Landaburu G, Banerjee S, Tao S, Reichholf N, Billinge SJL, Abécassis B, Jensen KMØ, De Roo J. An Amorphous Phase Precedes Crystallization: Unraveling the Colloidal Synthesis of Zirconium Oxide Nanocrystals. ACS NANO 2023; 17:8796-8806. [PMID: 37093055 PMCID: PMC10173684 DOI: 10.1021/acsnano.3c02149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
One can nowadays readily generate monodisperse colloidal nanocrystals, but the underlying mechanism of nucleation and growth is still a matter of intense debate. Here, we combine X-ray pair distribution function (PDF) analysis, small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM) to investigate the nucleation and growth of zirconia nanocrystals from zirconium chloride and zirconium isopropoxide at 340 °C, in the presence of surfactant (tri-n-octylphosphine oxide). Through E1 elimination, precursor conversion leads to the formation of small amorphous particles (less than 2 nm in diameter). Over the course of the reaction, the total particle concentration decreases while the concentration of nanocrystals stays constant after a sudden increase (nucleation). Kinetic modeling suggests that amorphous particles nucleate into nanocrystals through a second order process and they are also the source of nanocrystal growth. There is no evidence for a soluble monomer. The nonclassical nucleation is related to a precursor decomposition rate that is an order of magnitude higher than the observed crystallization rate. Using different zirconium precursors (e.g., ZrBr4 or Zr(OtBu)4), we can tune the precursor decomposition rate and thus control the nanocrystal size. We expect these findings to help researchers in the further development of colloidal syntheses.
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Affiliation(s)
- Rohan Pokratath
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Laurent Lermusiaux
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, 69364 Lyon, France
| | - Stefano Checchia
- ESRF Synchrotron, ID15A Beamline, 71 Avenue des Martyrs, CS40220, 38043 Grenoble, France
| | | | - Susan Rudd Cooper
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Jette Katja Mathiesen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
- Department of Physics, Technical University of Denmark, Fysikvej Bldg. 312, 2800 Kgs. Lyngby, Denmark
| | - Guillaume Landaburu
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, 69364 Lyon, France
| | - Soham Banerjee
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Songsheng Tao
- Applied Physics and Applied Mathematics Department, Columbia University, New York, New York 10027, United States
| | - Nico Reichholf
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Simon J L Billinge
- Applied Physics and Applied Mathematics Department, Columbia University, New York, New York 10027, United States
| | - Benjamin Abécassis
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, 69364 Lyon, France
| | - Kirsten M Ø Jensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Jonathan De Roo
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland
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9
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Zou Z, Beyerle ER, Tsai ST, Tiwary P. Driving and characterizing nucleation of urea and glycine polymorphs in water. Proc Natl Acad Sci U S A 2023; 120:e2216099120. [PMID: 36757888 PMCID: PMC9963467 DOI: 10.1073/pnas.2216099120] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/17/2023] [Indexed: 02/10/2023] Open
Abstract
Crystal nucleation is relevant across the domains of fundamental and applied sciences. However, in many cases, its mechanism remains unclear due to a lack of temporal or spatial resolution. To gain insights into the molecular details of nucleation, some form of molecular dynamics simulations is typically performed; these simulations, in turn, are limited by their ability to run long enough to sample the nucleation event thoroughly. To overcome the timescale limits in typical molecular dynamics simulations in a manner free of prior human bias, here, we employ the machine learning-augmented molecular dynamics framework "reweighted autoencoded variational Bayes for enhanced sampling (RAVE)." We study two molecular systems-urea and glycine-in explicit all-atom water, due to their enrichment in polymorphic structures and common utility in commercial applications. From our simulations, we observe multiple back-and-forth nucleation events of different polymorphs from homogeneous solution; from these trajectories, we calculate the relative ranking of finite-sized polymorph crystals embedded in solution, in terms of the free-energy difference between the finite-sized crystal polymorph and the original solution state. We further observe that the obtained reaction coordinates and transitions are highly nonclassical.
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Affiliation(s)
- Ziyue Zou
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD20742
| | - Eric R. Beyerle
- Institute for Physical Science and Technology, University of Maryland, College Park, MD20742
| | - Sun-Ting Tsai
- Department of Physics, University of Maryland, College Park, MD20742
| | - Pratyush Tiwary
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD20742
- Institute for Physical Science and Technology, University of Maryland, College Park, MD20742
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10
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Roth AN, Chen Y, Adamson MAS, Gi E, Wagner M, Rossini AJ, Vela J. Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability. ACS NANO 2022; 16:12024-12035. [PMID: 35849721 DOI: 10.1021/acsnano.2c02116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Increasing demand for effective energy conversion materials and devices has renewed interest in semiconductors comprised of earth-abundant and biocompatible elements. Alkaline-earth sulfides doped with rare earth ions are versatile optical materials. However, relatively little is known about controlling the dimensionality, surface chemistry, and inherent optical properties of the undoped versions of alkaline-earth mono- and polychalcogenides. We describe the colloidal synthesis of alkaline-earth chalcogenide nanocrystals through the reaction of metal carboxylates with carbon disulfide or selenourea. Systematic exploration of the synthetic phase space allows us to tune particle sizes over a wide range using a mixture of commercially available carboxylate precursors. Solid-state NMR spectroscopy confirms the phase purity of the selenide compositions. Surface characterization reveals that bridging carboxylates and amines preferentially terminate the surface of the nanocrystals. While these materials are colloidally stable in the mother solution, the selenides are susceptible to oxidation over time, eventually degrading to selenium metal through polyselenide intermediates. As part of these investigations, we have developed the colloidal syntheses of barium di- and triselenides, two among few reported nanocrystalline alkaline-earth polychalcogenides. Electronic structure calculations reveal that both materials are indirect band gap semiconductors. The colloidal chemistry presented here may enable the synthesis of more complex, multinary chalcogenide materials containing alkaline-earth elements.
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Affiliation(s)
- Alison N Roth
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Yunhua Chen
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Marquix A S Adamson
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Eunbyeol Gi
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Molly Wagner
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
| | - Aaron J Rossini
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Javier Vela
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
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