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Homer MK, Larson HC, Dixon GJ, Miura-Stempel E, Armstrong NR, Cossairt BM. Extremely Long-Lived Charge Donor States Formed by Visible Irradiation of Quantum Dots. ACS NANO 2024; 18:24591-24602. [PMID: 39161977 DOI: 10.1021/acsnano.4c10526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
Using cyclic voltammetry under illumination, we recently demonstrated that CdS quantum dots (QDs) form charge donor states that live for at least several minutes after illumination ends, ∼12 orders of magnitude longer than expected for free carriers. This time scale suggests that the conventionally accepted mechanism of charge transfer, wherein charges directly transfer to an acceptor following exciton dissociation, cannot be complete. Because of these long time scales, this unconventional pathway is not readily observed using time-resolved spectroscopy to probe charge transfer dynamics. Here, we investigated the chemical nature of these charge donor states using cyclic voltammetry under illumination coupled with NMR spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and optical spectroscopy. Our data reveal that charges are stored locally rather than as free carriers, and the number of charges stored is dependent on the QD surface ligation and stoichiometry. Altogether, our results confirm that electrons are stored at ligated surface Cd, these sites are competent charge donors, and this storage is charge balanced by X-type ligand desorption. We found that charge storage occurs in every QD system studied, including CdS, CdSe, and InP capped with carboxylate and phosphonate ligands.
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Affiliation(s)
- Micaela K Homer
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Helen C Larson
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Grant J Dixon
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Emily Miura-Stempel
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Neal R Armstrong
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arkansas 85721, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Chen LX, Yano J. Deciphering Photoinduced Catalytic Reaction Mechanisms in Natural and Artificial Photosynthetic Systems on Multiple Temporal and Spatial Scales Using X-ray Probes. Chem Rev 2024; 124:5421-5469. [PMID: 38663009 DOI: 10.1021/acs.chemrev.3c00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
Utilization of renewable energies for catalytically generating value-added chemicals is highly desirable in this era of rising energy demands and climate change impacts. Artificial photosynthetic systems or photocatalysts utilize light to convert abundant CO2, H2O, and O2 to fuels, such as carbohydrates and hydrogen, thus converting light energy to storable chemical resources. The emergence of intense X-ray pulses from synchrotrons, ultrafast X-ray pulses from X-ray free electron lasers, and table-top laser-driven sources over the past decades opens new frontiers in deciphering photoinduced catalytic reaction mechanisms on the multiple temporal and spatial scales. Operando X-ray spectroscopic methods offer a new set of electronic transitions in probing the oxidation states, coordinating geometry, and spin states of the metal catalytic center and photosensitizers with unprecedented energy and time resolution. Operando X-ray scattering methods enable previously elusive reaction steps to be characterized on different length scales and time scales. The methodological progress and their application examples collected in this review will offer a glimpse into the accomplishments and current state in deciphering reaction mechanisms for both natural and synthetic systems. Looking forward, there are still many challenges and opportunities at the frontier of catalytic research that will require further advancement of the characterization techniques.
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Affiliation(s)
- Lin X Chen
- Chemical Science and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Junko Yano
- Molecular Biophysics & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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3
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Li Q, Wu K, Zhu H, Yang Y, He S, Lian T. Charge Transfer from Quantum-Confined 0D, 1D, and 2D Nanocrystals. Chem Rev 2024; 124:5695-5763. [PMID: 38629390 PMCID: PMC11082908 DOI: 10.1021/acs.chemrev.3c00742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 03/29/2024] [Accepted: 04/02/2024] [Indexed: 05/09/2024]
Abstract
The properties of colloidal quantum-confined semiconductor nanocrystals (NCs), including zero-dimensional (0D) quantum dots, 1D nanorods, 2D nanoplatelets, and their heterostructures, can be tuned through their size, dimensionality, and material composition. In their photovoltaic and photocatalytic applications, a key step is to generate spatially separated and long-lived electrons and holes by interfacial charge transfer. These charge transfer properties have been extensively studied recently, which is the subject of this Review. The Review starts with a summary of the electronic structure and optical properties of 0D-2D nanocrystals, followed by the advances in wave function engineering, a novel way to control the spatial distribution of electrons and holes, through their size, dimension, and composition. It discusses the dependence of NC charge transfer on various parameters and the development of the Auger-assisted charge transfer model. Recent advances in understanding multiple exciton generation, decay, and dissociation are also discussed, with an emphasis on multiple carrier transfer. Finally, the applications of nanocrystal-based systems for photocatalysis are reviewed, focusing on the photodriven charge separation and recombination processes that dictate the function and performance of these materials. The Review ends with a summary and outlook of key remaining challenges and promising future directions in the field.
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Affiliation(s)
- Qiuyang Li
- Department
of Physics, University of Michigan, 450 Church St, Ann Arbor, Michigan 48109, United States
| | - Kaifeng Wu
- State
Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation
Center of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiming Zhu
- Department
of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Ye Yang
- The
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM
(Collaborative Innovation Center of Chemistry for Energy Materials),
College of Chemistry & Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Sheng He
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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4
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Shulenberger KE, Jilek MR, Sherman SJ, Hohman BT, Dukovic G. Electronic Structure and Excited State Dynamics of Cadmium Chalcogenide Nanorods. Chem Rev 2023; 123:3852-3903. [PMID: 36881852 DOI: 10.1021/acs.chemrev.2c00676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The cylindrical quasi-one-dimensional shape of colloidal semiconductor nanorods (NRs) gives them unique electronic structure and optical properties. In addition to the band gap tunability common to nanocrystals, NRs have polarized light absorption and emission and high molar absorptivities. NR-shaped heterostructures feature control of electron and hole locations as well as light emission energy and efficiency. We comprehensively review the electronic structure and optical properties of Cd-chalcogenide NRs and NR heterostructures (e.g., CdSe/CdS dot-in-rods, CdSe/ZnS rod-in-rods), which have been widely investigated over the last two decades due in part to promising optoelectronic applications. We start by describing methods for synthesizing these colloidal NRs. We then detail the electronic structure of single-component and heterostructure NRs and follow with a discussion of light absorption and emission in these materials. Next, we describe the excited state dynamics of these NRs, including carrier cooling, carrier and exciton migration, radiative and nonradiative recombination, multiexciton generation and dynamics, and processes that involve trapped carriers. Finally, we describe charge transfer from photoexcited NRs and connect the dynamics of these processes with light-driven chemistry. We end with an outlook that highlights some of the outstanding questions about the excited state properties of Cd-chalcogenide NRs.
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Affiliation(s)
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Benjamin T Hohman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States.,Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
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5
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A Fluorescent Detection for Paraquat Based on β-CDs-Enhanced Fluorescent Gold Nanoclusters. Foods 2021; 10:foods10061178. [PMID: 34073830 PMCID: PMC8225061 DOI: 10.3390/foods10061178] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/06/2021] [Accepted: 05/11/2021] [Indexed: 12/13/2022] Open
Abstract
In this report, a fluorescent sensing method for paraquat based on gold nanoclusters (AuNCs) is proposed. It was found that paraquat could quench both glutathione-capped AuNCs (GSH-AuNCs) and β-cyclodextrin-modified GSH-AuNCs (GSH/β-CDs-AuNCs). The modification of β-CDs on the surface of GSH-AuNCs obviously enhanced the fluorescence intensity of GSH-AuNCs and improved the sensitivity of paraquat sensing more than 4-fold. This sensibilization was ascribed to the obvious fluorescence intensity enhancement of GSH-AuNCs by β-CDs and the “host–guest” interaction between paraquat and β-CDs. The fluorescence quenching was mainly due to the photoinduced energy transfer (PET) between GSH/β-CDs-AuNCs and paraquat. With the optimized β-CDs modification of the GSH-AuNC surfaces and under buffer conditions, the fluorescent detection for paraquat demonstrated a linear response in the range of 5.0–350 ng/mL with a detection limit of 1.2 ng/mL. The fluorescent method also showed high selectivity toward common pesticides. The interference from metal ions could be easily masked by ethylene diamine tetraacetic acid (EDTA). This method was applied to the measurement of paraquat-spiked water samples and good recoveries (93.6–103.8%) were obtained. The above results indicate that host molecule modification of fluorescent metal NC surfaces has high potential in the development of robust fluorescent sensors.
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6
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Cherepanov DA, Gostev FE, Shelaev IV, Denisov NN, Nadtochenko VA. Monitoring the electric field in CdSe quantum dots under ultrafast interfacial electron transfer via coherent phonon dynamics. NANOSCALE 2018; 10:22409-22419. [PMID: 30475371 DOI: 10.1039/c8nr07644h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Coherent phonon dynamics in CdSe quantum dots (QD) under an ultrafast electron transfer (ET) reaction of the (1Se-1S3/2) exciton quenched by methyl viologen (MV2+) adsorbed onto the QD surface was studied by ultrafast pump-probe spectroscopy. Frequency and amplitude modulations (FM, AM) of the transient absorption ΔA(ωprobe,t) in the pure CdSe and coupled CdSe/MV2+ QDs were identified in the bleach band dynamics of the red-edge exciton. The fast Fourier transform (FFT) and continuous wavelet transform analysis of the FM and AM oscillations revealed peaks at 0.51-0.58 THz (17-19 cm-1) and 6.06-6.27 THz (202-209 cm-1) attributed to the longitudinal acoustic (LA) and longitudinal optical (LO) phonons, respectively. The electron transfer to MV2+ proceeded non-exponentially with effective time constants of 164 fs (∼30%) and 540 fs (∼70%). The quantum yield of MV˙+ radical formation was 40 ± 5%. It implies a fast route for the electron-hole pair [h+…MV˙+] recombination that can be rationalized in accordance with the adiabatic ET mechanism at the semiconductor surface. In the coupled CdSe/MV2+ QDs, the amplitude of the FM oscillations rose considerably with time despite the natural attenuation of the phonon amplitude due to decoherence processes. A kinetic model explaining the increase of FM oscillations is proposed. The surprising growth of FM oscillations is elucidated by the kinetic model taking into account the relatively slow damping of LO phonon oscillations (∼1.5 ps), the ultrafast ET to MV2+, and the quantum yield of charge separation [h+…MV˙+] (∼40%). The fast formation of the charge-separated pair [h+…MV˙+] suggests the appearance of an electric field F with a strength of ∼3 × 106 V cm-1. The MV2+ reduction substantially increased the magnitude of LA phonon oscillations. Since the ET time is shorter than the period of LA phonon oscillations (∼1.8 ps), the MV2+ reduction substantially increased the magnitude of LA phonon oscillations due to the inverse piezoelectric effect. The CdSe nanocrystals exposed to the electric field F exhibit the quantum-confined Stark and Franz-Keldysh electro-absorption effects. The proposed kinetic model gives consideration to the dynamic Stark shift of the red-edge exciton and to the increased amplitude of LO phonon oscillations in the bleach band dynamics.
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Affiliation(s)
- Dmitry A Cherepanov
- N.Semenov Institute of Chemical Physics Russian Academy of Sciences, Kosigin str.4, Moscow, 119991, Russia.
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7
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Sekhar MC, Paul S, De A, Samanta A. An Ultrafast Transient Absorption Study of Charge Separation and Recombination Dynamics in CdSe QDs and Methyl Viologen: Dependence on Surface Stoichiometry. ChemistrySelect 2018. [DOI: 10.1002/slct.201800313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- M. Chandra Sekhar
- School of Chemistry; University of Hyderabad; Hyderabad 500046 India
| | - Sneha Paul
- School of Chemistry; University of Hyderabad; Hyderabad 500046 India
| | - Apurba De
- School of Chemistry; University of Hyderabad; Hyderabad 500046 India
| | - Anunay Samanta
- School of Chemistry; University of Hyderabad; Hyderabad 500046 India
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8
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Werwie M, Dworak L, Bottin A, Mayer L, Basché T, Wachtveitl J, Paulsen H. Light-harvesting chlorophyll protein (LHCII) drives electron transfer in semiconductor nanocrystals. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2018; 1859:174-181. [PMID: 29247606 DOI: 10.1016/j.bbabio.2017.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/29/2017] [Accepted: 12/12/2017] [Indexed: 11/23/2022]
Abstract
Type-II quantum dots (QDs) are capable of light-driven charge separation between their core and the shell structures; however, their light absorption is limited in the longer-wavelength range. Biological light-harvesting complex II (LHCII) efficiently absorbs in the blue and red spectral domains. Therefore, hybrid complexes of these two structures may be promising candidates for photovoltaic applications. Previous measurements had shown that LHCII bound to QD can transfer its excitation energy to the latter, as indicated by the fluorescence emissions of LHCII and QD being quenched and sensitized, respectively. In the presence of methyl viologen (MV), both fluorescence emissions are quenched, indicating an additional electron transfer process from QDs to MV. Transient absorption spectroscopy confirmed this notion and showed that electron transfer from QDs to MV is much faster than fluorescence energy transfer between LHCII and QD. The action spectrum of MV reduction by LHCII-QD complexes reflected the LHCII absorption spectrum, showing that light absorbed by LHCII and transferred to QDs increased the efficiency of MV reduction by QDs. Under continuous illumination, at least 28 turnovers were observed for the MV reduction. Presumably, the holes in QD cores were filled by a reducing agent in the reaction solution or by the dihydrolipoic-acid coating of the QDs. The LHCII-QD construct can be viewed as a simple model of a photosystem with the QD component acting as reaction center.
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Affiliation(s)
- Mara Werwie
- Institut für Molekulare Physiologie, Johannes-Gutenberg-Universität Mainz, Johannes-von-Müller-Weg 6, 55099 Mainz, Germany
| | - Lars Dworak
- Institut für Physikalische und Theoretische Chemie, Max-von-Laue-Straße 7, Gebäude N120/224, 60438 Frankfurt am Main, Germany
| | - Anne Bottin
- Institut für Physikalische Chemie, Johannes-Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Lisa Mayer
- Institut für Molekulare Physiologie, Johannes-Gutenberg-Universität Mainz, Johannes-von-Müller-Weg 6, 55099 Mainz, Germany
| | - Thomas Basché
- Institut für Physikalische Chemie, Johannes-Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Josef Wachtveitl
- Institut für Physikalische und Theoretische Chemie, Max-von-Laue-Straße 7, Gebäude N120/224, 60438 Frankfurt am Main, Germany
| | - Harald Paulsen
- Institut für Molekulare Physiologie, Johannes-Gutenberg-Universität Mainz, Johannes-von-Müller-Weg 6, 55099 Mainz, Germany.
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9
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Dworak L, Roth S, Scheffer MP, Frangakis AS, Wachtveitl J. A thin CdSe shell boosts the electron transfer from CdTe quantum dots to methylene blue. NANOSCALE 2018; 10:2162-2169. [PMID: 29327031 DOI: 10.1039/c7nr08287h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
CdTe core and CdTe/CdSe core/shell quantum dots (QD) are investigated with steady state and time-resolved spectroscopic methods. The coating of the CdTe core with a 0.7 nm thick CdSe shell shifts the lowest exciton absorption band to the red by more than 70 nm making the CdTe/CdSe QD an interesting candidate for application in solar energy conversion. Femtosecond transient absorption measurements are applied to study the photoinduced electron transfer (ET) to the molecular acceptor methylene blue (MB). ET times after single excitation of the QD are determined for different MB : QD ratios. The ET reaction is significantly faster in the case of the MB-CdTe/CdSe QD complexes, indicative of an altered charge distribution in the photoexcited heterostructure with a higher electron density in the CdSe shell. As a result of the efficient absorption of incoming light and the faster ET reaction, the amount of reduced MB in the time resolved experiments is higher for CdTe/CdSe QD compared to CdTe QD.
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Affiliation(s)
- L Dworak
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
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10
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Harris RD, Bettis Homan S, Kodaimati M, He C, Nepomnyashchii AB, Swenson NK, Lian S, Calzada R, Weiss EA. Electronic Processes within Quantum Dot-Molecule Complexes. Chem Rev 2016; 116:12865-12919. [PMID: 27499491 DOI: 10.1021/acs.chemrev.6b00102] [Citation(s) in RCA: 171] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The subject of this review is the colloidal quantum dot (QD) and specifically the interaction of the QD with proximate molecules. It covers various functions of these molecules, including (i) ligands for the QDs, coupled electronically or vibrationally to localized surface states or to the delocalized states of the QD core, (ii) energy or electron donors or acceptors for the QDs, and (iii) structural components of QD assemblies that dictate QD-QD or QD-molecule interactions. Research on interactions of ligands with colloidal QDs has revealed that ligands determine not only the excited state dynamics of the QD but also, in some cases, its ground state electronic structure. Specifically, the article discusses (i) measurement of the electronic structure of colloidal QDs and the influence of their surface chemistry, in particular, dipolar ligands and exciton-delocalizing ligands, on their electronic energies; (ii) the role of molecules in interfacial electron and energy transfer processes involving QDs, including electron-to-vibrational energy transfer and the use of the ligand shell of a QD as a semipermeable membrane that gates its redox activity; and (iii) a particular application of colloidal QDs, photoredox catalysis, which exploits the combination of the electronic structure of the QD core and the chemistry at its surface to use the energy of the QD excited state to drive chemical reactions.
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Affiliation(s)
- Rachel D Harris
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Stephanie Bettis Homan
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Mohamad Kodaimati
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Chen He
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | | | - Nathaniel K Swenson
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Shichen Lian
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Raul Calzada
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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11
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Li H, Liu J, Yang X. Facile Synthesis of Glutathione-capped CdS Quantum Dots as a Fluorescence Sensor for Rapid Detection and Quantification of Paraquat. ANAL SCI 2016; 31:1011-7. [PMID: 26460365 DOI: 10.2116/analsci.31.1011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This paper describes a convenient and rapid fluorescence sensor for determination of paraquat (PA) based on glutathione-capped CdS quantum dots (QDs). The methodology enabled the use of a simple synthesis procedure for water solubilization of CdS QDs via a fast route using glutathione as a capping agent within 15 min. The resulting water-soluble QDs exhibit a strong fluorescence emission at 536 nm with high and reproducible photostability. PA is an important class of electron acceptors for QDs. Thus, the fluorescence intensity of the glutathione-capped CdS QDs probe could be dramatically quenched by PA due to the electron transfer mechanism. The fluorescence intensity of the CdS QDs system was proportional to PA concentration in the range of 0.025 to 1.5 μg mL(-1), with a detection limit of 0.01 μg mL(-1). The time of analysis sample, including preparation of QDs and fluorescent measurement for PA, was only 20 min. Most of the potentially coexisting substances did not interfere with the PA-induced quenching effect except diquat. Furthermore, the analytical applicability of the proposed method was demonstrated by analyzing PA in water, rice and cabbage samples, and the recoveries were between 86 and 105% which satisfied the requirement of detection for PA. These results showed that the proposed method was simple in design and fast in operation, and could be used as a sensitive tool for detecting PA in environmental and agricultural samples.
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12
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Young RM, Jensen SC, Edme K, Wu Y, Krzyaniak MD, Vermeulen NA, Dale EJ, Stoddart JF, Weiss EA, Wasielewski MR, Co DT. Ultrafast Two-Electron Transfer in a CdS Quantum Dot-Extended-Viologen Cyclophane Complex. J Am Chem Soc 2016; 138:6163-70. [PMID: 27111529 DOI: 10.1021/jacs.5b13386] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Time-resolved optical spectroscopies reveal multielectron transfer from the biexcitonic state of a CdS quantum dot to an adsorbed tetracationic compound cyclobis(4,4'-(1,4-phenylene) bipyridin-1-ium-1,4-phenylene-bis(methylene)) (ExBox(4+)) to form both the ExBox(3+•) and the doubly reduced ExBox(2(+•)) states from a single laser pulse. Electron transfer in the single-exciton regime occurs in 1 ps. At higher excitation powers the second electron transfer takes ∼5 ps, which leads to a mixture of redox states of the acceptor ligand. The doubly reduced ExBox(2(+•)) state has a lifetime of ∼10 ns, while CdS(+•):ExBox(3+•) recombines with multiple time constants, the longest of which is ∼300 μs. The long-lived charge separation and ability to accumulate multiple charges on ExBox(4+) demonstrate the potential of the CdS:ExBox(4+) complex to serve as a platform for two-electron photocatalysis.
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Affiliation(s)
- Ryan M Young
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Stephen C Jensen
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Kedy Edme
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Yilei Wu
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Matthew D Krzyaniak
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Nicolaas A Vermeulen
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Edward J Dale
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - J Fraser Stoddart
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Dick T Co
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
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13
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Abstract
Understanding photoinduced charge transfer from nanomaterials is essential to the many applications of these materials. This review summarizes recent progress in understanding charge transfer from quantum dots (QDs), an ideal model system for investigating fundamental charge transfer properties of low-dimensional quantum-confined nanomaterials. We first discuss charge transfer from QDs to weakly coupled acceptors within the framework of Marcus nonadiabatic electron transfer (ET) theory, focusing on the dependence of ET rates on reorganization energy, electronic coupling, and driving force. Because of the strong electron-hole interaction, we show that ET from QDs should be described by the Auger-assisted ET model, which is significantly different from ET between molecules or from bulk semiconductor electrodes. For strongly quantum-confined QDs on semiconductor surfaces, the coupling can fall within the strong coupling limit, in which case the donor-acceptor interaction and ET properties can be described by the Newns-Anderson model of chemisorption. We also briefly discuss recent progress in controlling charge transfer properties in quantum-confined nanoheterostructures through wavefunction engineering and multiple exciton dissociation. Finally, we identify a few key areas for further research.
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Affiliation(s)
- Haiming Zhu
- Department of Chemistry, Emory University, Atlanta, Georgia 30322;
| | - Ye Yang
- Department of Chemistry, Emory University, Atlanta, Georgia 30322;
| | - Kaifeng Wu
- Department of Chemistry, Emory University, Atlanta, Georgia 30322;
| | - Tianquan Lian
- Department of Chemistry, Emory University, Atlanta, Georgia 30322;
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14
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Brown KA, Song Q, Mulder DW, King PW. Diameter dependent electron transfer kinetics in semiconductor-enzyme complexes. ACS NANO 2014; 8:10790-8. [PMID: 25244026 DOI: 10.1021/nn504561v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Excited state electron transfer (ET) is a fundamental step for the catalytic conversion of solar energy into chemical energy. To understand the properties controlling ET between photoexcited nanoparticles and catalysts, the ET kinetics were measured for solution-phase complexes of CdTe quantum dots and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) using time-resolved photoluminescence spectroscopy. Over a 2.0-3.5 nm diameter range of CdTe nanoparticles, the observed ET rate (kET) was sensitive to CaI concentration. To account for diameter effects on CaI binding, a Langmuir isotherm and two geometric binding models were created to estimate maximal CaI affinities and coverages at saturating concentrations. Normalizing the ET kinetics to CaI surface coverage for each CdTe diameter led to k(ET) values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (ΔGET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe-CaI complexes was measured at several molar ratios. Normalization for diameter-dependent changes in CaI coverage showed an increase in TOF with diameter. These results suggest that k(ET) and H2 production for CdTe-CaI complexes are not strictly controlled by ΔG(ET) and that other factors must be considered.
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Affiliation(s)
- Katherine A Brown
- Biosciences Center, National Renewable Energy Laboratory , Golden, Colorado 80401, United States
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15
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Romanova J, Liégeois V, Champagne B. Resonant Raman spectra of molecules with diradical character: multiconfigurational wavefunction investigation of neutral viologens. Phys Chem Chem Phys 2014; 16:21721-31. [DOI: 10.1039/c4cp02977a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In search for a relationship between the diradical character and resonance Raman signatures of neutral viologens by multiconfigurational methods.
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Affiliation(s)
- Julia Romanova
- Laboratoire de Chimie Théorique
- Unité de Chimie Physique Théorique et Structurale (UCPTS)
- University of Namur
- 5000 Namur, Belgium
| | - Vincent Liégeois
- Laboratoire de Chimie Théorique
- Unité de Chimie Physique Théorique et Structurale (UCPTS)
- University of Namur
- 5000 Namur, Belgium
| | - Benoît Champagne
- Laboratoire de Chimie Théorique
- Unité de Chimie Physique Théorique et Structurale (UCPTS)
- University of Namur
- 5000 Namur, Belgium
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16
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Durán GM, Contento AM, Ríos Á. Use of Cdse/ZnS quantum dots for sensitive detection and quantification of paraquat in water samples. Anal Chim Acta 2013; 801:84-90. [DOI: 10.1016/j.aca.2013.09.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/31/2013] [Accepted: 09/03/2013] [Indexed: 01/31/2023]
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17
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Zhao J, Holmes MA, Osterloh FE. Quantum confinement controls photocatalysis: a free energy analysis for photocatalytic proton reduction at CdSe nanocrystals. ACS NANO 2013; 7:4316-25. [PMID: 23590186 DOI: 10.1021/nn400826h] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The ability to adjust the mechanical, optical, magnetic, electric, and chemical properties of materials via the quantum confinement effect is well-understood. Here, we provide the first quantitative analysis of quantum-size-controlled photocatalytic H2 evolution at the semiconductor-solution interface. Specifically, it is found that the hydrogen evolution rate from illuminated suspended CdSe quantum dots in aqueous sodium sulfite solution depends on nanocrystal size. Photoelectrochemical measurements on CdSe nanocrystal films reveal that the observed reactivity is controlled by the free energy change of the system, as determined by the proton reduction potential and the quasi-Fermi energy of the dots. The corresponding free energy change can be fitted to the photocatalytic activity using a modified Butler-Volmer equation for reaction kinetics. These findings establish a quantitative experimental basis for quantum-confinement-controlled proton reduction with semiconductor nanocrystals. Electrochemical data further indicate that proton reduction occurs at cadmium sites on the dots, and that charge separation in these nanocrystals is controlled by surface effects, not by space charge layers.
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Affiliation(s)
- Jing Zhao
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
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18
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Wu K, Song N, Liu Z, Zhu H, Rodríguez-Córdoba W, Lian T. Interfacial charge separation and recombination in InP and quasi-type II InP/CdS core/shell quantum dot-molecular acceptor complexes. J Phys Chem A 2013; 117:7561-70. [PMID: 23639000 DOI: 10.1021/jp402425w] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Recent studies of group II-VI colloidal semiconductor heterostuctures, such as CdSe/CdS core/shell quantum dots (QDs) or dot-in-rod nanorods, show that type II and quasi-type II band alignment can facilitate electron transfer and slow down charge recombination in QD-molecular electron acceptor complexes. To explore the general applicability of this wave function engineering approach for controlling charge transfer properties, we investigate exciton relaxation and dissociation dynamics in InP (a group III-V semiconductor) and InP/CdS core/shell (a heterostructure beween group III-V and II-VI semiconductors) QDs by transient absorption spectroscopy. We show that InP/CdS QDs exhibit a quasi-type II band alignment with the 1S electron delocalized throughout the core and shell and the 1S hole confined in the InP core. In InP-methylviologen (MV(2+)) complexes, excitons in the QD can be dissociated by ultrafast electron transfer to MV(2+) from the 1S electron level (with an average time constant of 11.4 ps) as well as 1P and higher electron levels (with a time constant of 0.39 ps), which is followed by charge recombination to regenerate the complex in its ground state (with an average time constant of 47.1 ns). In comparison, InP/CdS-MV(2+) complexes show similar ultrafast charge separation and 5-fold slower charge recombination rates, consistent with the quasi-type II band alignment in these heterostructures. This result demonstrates that wave function engineering in nanoheterostructures of group III-V and II-VI semiconductors provides a promising approach for optimizing their light harvesting and charge separation for solar energy conversion applications.
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Affiliation(s)
- Kaifeng Wu
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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19
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Petryayeva E, Algar WR, Medintz IL. Quantum dots in bioanalysis: a review of applications across various platforms for fluorescence spectroscopy and imaging. APPLIED SPECTROSCOPY 2013; 67:215-52. [PMID: 23452487 DOI: 10.1366/12-06948] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Semiconductor quantum dots (QDs) are brightly luminescent nanoparticles that have found numerous applications in bioanalysis and bioimaging. In this review, we highlight recent developments in these areas in the context of specific methods for fluorescence spectroscopy and imaging. Following a primer on the structure, properties, and biofunctionalization of QDs, we describe select examples of how QDs have been used in combination with steady-state or time-resolved spectroscopic techniques to develop a variety of assays, bioprobes, and biosensors that function via changes in QD photoluminescence intensity, polarization, or lifetime. Some special attention is paid to the use of Förster resonance energy transfer-type methods in bioanalysis, including those based on bioluminescence and chemiluminescence. Direct chemiluminescence, electrochemiluminescence, and charge transfer quenching are similarly discussed. We further describe the combination of QDs and flow cytometry, including traditional cellular analyses and spectrally encoded barcode-based assay technologies, before turning our attention to enhanced fluorescence techniques based on photonic crystals or plasmon coupling. Finally, we survey the use of QDs across different platforms for biological fluorescence imaging, including epifluorescence, confocal, and two-photon excitation microscopy; single particle tracking and fluorescence correlation spectroscopy; super-resolution imaging; near-field scanning optical microscopy; and fluorescence lifetime imaging microscopy. In each of the above-mentioned platforms, QDs provide the brightness needed for highly sensitive detection, the photostability needed for tracking dynamic processes, or the multiplexing capacity needed to elucidate complex systems. There is a clear synergy between advances in QD materials and spectroscopy and imaging techniques, as both must be applied in concert to achieve their full potential.
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Affiliation(s)
- Eleonora Petryayeva
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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Wilker MB, Schnitzenbaumer KJ, Dukovic G. Recent Progress in Photocatalysis Mediated by Colloidal II-VI Nanocrystals. Isr J Chem 2012; 52:1002-1015. [PMID: 24115781 PMCID: PMC3791552 DOI: 10.1002/ijch.201200073] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/29/2012] [Indexed: 12/14/2022]
Abstract
The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H2 generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal-semiconductor nano-heterostructures.
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Affiliation(s)
- Molly B Wilker
- Department of Chemistry and Biochemistry, University of Colorado BoulderBoulder, CO 80309, USA
| | - Kyle J Schnitzenbaumer
- Department of Chemistry and Biochemistry, University of Colorado BoulderBoulder, CO 80309, USA
| | - Gordana Dukovic
- Department of Chemistry and Biochemistry, University of Colorado BoulderBoulder, CO 80309, USA
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21
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Stewart MH, Huston AL, Scott AM, Efros AL, Melinger JS, Gemmill KB, Trammell SA, Blanco-Canosa JB, Dawson PE, Medintz IL. Complex Förster energy transfer interactions between semiconductor quantum dots and a redox-active osmium assembly. ACS NANO 2012; 6:5330-5347. [PMID: 22671940 DOI: 10.1021/nn301177h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The ability of luminescent semiconductor quantum dots (QDs) to engage in diverse energy transfer processes with organic dyes, light-harvesting proteins, metal complexes, and redox-active labels continues to stimulate interest in developing them for biosensing and light-harvesting applications. Within biosensing configurations, changes in the rate of energy transfer between the QD and the proximal donor, or acceptor, based upon some external (biological) event form the principle basis for signal transduction. However, designing QD sensors to function optimally is predicated on a full understanding of all relevant energy transfer mechanisms. In this report, we examine energy transfer between a range of CdSe-ZnS core-shell QDs and a redox-active osmium(II) polypyridyl complex. To facilitate this, the Os complex was synthesized as a reactive isothiocyanate and used to label a hexahistidine-terminated peptide. The Os-labeled peptide was ratiometrically self-assembled to the QDs via metal affinity coordination, bringing the Os complex into close proximity of the nanocrystal surface. QDs displaying different emission maxima were assembled with increasing ratios of Os-peptide complex and subjected to detailed steady-state, ultrafast transient absorption, and luminescence lifetime decay analyses. Although the possibility exists for charge transfer quenching interactions, we find that the QD donors engage in relatively efficient Förster resonance energy transfer with the Os complex acceptor despite relatively low overall spectral overlap. These results are in contrast to other similar QD donor-redox-active acceptor systems with similar separation distances, but displaying far higher spectral overlap, where charge transfer processes were reported to be the dominant QD quenching mechanism.
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Affiliation(s)
- Michael H Stewart
- Optical Sciences Division, Code 5611, U.S. Naval Research Laboratory, Washington, DC 20375, USA.
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