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Hernandez F, Yang M, Nagelj N, Lee AY, Noh H, Hur KP, Fu X, Savoie CJ, Schwartzberg AM, Olshansky JH. The role of surface functionalization in quantum dot-based photocatalytic CO 2 reduction: balancing efficiency and stability. NANOSCALE 2024. [PMID: 38414382 DOI: 10.1039/d3nr06177a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Photocatalytic CO2 reduction offers a promising strategy to produce hydrocarbons without reliance on fossil fuels. Visible light-absorbing colloidal nanomaterials composed of earth-abundant metals suspended in aqueous media are particularly attractive owing to their low-cost, ease of separation, and highly modifiable surfaces. The current study explores such a system by employing water-soluble ZnSe quantum dots and a Co-based molecular catalyst. Water solubilization of the quantum dots is achieved with either carboxylate (3-mercaptopropionic acid) or ammonium (2-aminoethanethiol) functionalized ligands to produce nanoparticles with either negatively or positively-charged surfaces. Photocatalysis experiments are performed to compare the effectiveness of these two surface functionalization strategies on CO2 reduction and ultrafast spectroscopy is used to reveal the underlying photoexcited charge dynamics. We find that the positively-charged quantum dots can support sub-picosecond electron transfer to the carboxylate-based molecular catalyst and also produce >30% selectivity for CO and >170 mmolCO gZnSe-1. However, aggregation reduces activity in approximately one day. In contrast, the negatively-charged quantum dots exhibit >10 ps electron transfer and substantially lower CO selectivity, but they are colloidally stable for days. These results highlight the importance of the quantum dot-catalyst interaction for CO2 reduction. Furthermore, multi-dentate catalyst molecules create a trade-off between photocatalytic efficiency from strong interactions and deleterious aggregation of quantum dot-catalyst assemblies.
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Affiliation(s)
- Frida Hernandez
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Maggie Yang
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Nejc Nagelj
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Autumn Y Lee
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Hasun Noh
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Kyle P Hur
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Xinyu Fu
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Caleb J Savoie
- Department of Chemistry, Amherst College, Amherst, MA 01002, USA.
| | - Adam M Schwartzberg
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Khan ZU, Khan LU, Brito HF, Gidlund M, Malta OL, Di Mascio P. Colloidal Quantum Dots as an Emerging Vast Platform and Versatile Sensitizer for Singlet Molecular Oxygen Generation. ACS OMEGA 2023; 8:34328-34353. [PMID: 37779941 PMCID: PMC10536110 DOI: 10.1021/acsomega.3c03962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/15/2023] [Indexed: 10/03/2023]
Abstract
Singlet molecular oxygen (1O2) has been reported in wide arrays of applications ranging from optoelectronic to photooxygenation reactions and therapy in biomedical proposals. It is also considered a major determinant of photodynamic therapy (PDT) efficacy. Since the direct excitation from the triplet ground state (3O2) of oxygen to the singlet excited state 1O2 is spin forbidden; therefore, a rational design and development of heterogeneous sensitizers is remarkably important for the efficient production of 1O2. For this purpose, quantum dots (QDs) have emerged as versatile candidates either by acting individually as sensitizers for 1O2 generation or by working in conjunction with other inorganic materials or organic sensitizers by providing them a vast platform. Thus, conjoining the photophysical properties of QDs with other materials, e.g., coupling/combining with other inorganic materials, doping with the transition metal ions or lanthanide ions, and conjugation with a molecular sensitizer provide the opportunity to achieve high-efficiency quantum yields of 1O2 which is not possible with either component separately. Hence, the current review has been focused on the recent advances made in the semiconductor QDs, perovskite QDs, and transition metal dichalcogenide QD-sensitized 1O2 generation in the context of ongoing and previously published research work (over the past eight years, from 2015 to 2023).
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Affiliation(s)
- Zahid U. Khan
- Institute
of Chemistry, University of Sao Paulo (USP), 05508-000 São
Paulo-SP, Brazil
| | - Latif U. Khan
- Institute
of Chemistry, University of Sao Paulo (USP), 05508-000 São
Paulo-SP, Brazil
- Synchrotron-light
for Experimental Science and Applications in the Middle East (SESAME), P.O. Box 7, Allan 19252, Jordan
| | - Hermi F. Brito
- Institute
of Chemistry, University of Sao Paulo (USP), 05508-000 São
Paulo-SP, Brazil
| | - Magnus Gidlund
- Institute
of Biomedical Sciences-IV, University of
Sao Paulo (USP), 05508-000 São Paulo-SP, Brazil
| | - Oscar L. Malta
- Departamento
de Química Fundamental, Universidade
Federal de Pernambuco, Recife, PE 50740-560, Brazil
| | - Paolo Di Mascio
- Institute
of Chemistry, University of Sao Paulo (USP), 05508-000 São
Paulo-SP, Brazil
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Dou FY, Harvey SM, Mason KG, Homer MK, Gamelin DR, Cossairt BM. Effect of a redox-mediating ligand shell on photocatalysis by CdS quantum dots. J Chem Phys 2023; 158:2889496. [PMID: 37158330 DOI: 10.1063/5.0144896] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/19/2023] [Indexed: 05/10/2023] Open
Abstract
Semiconductor quantum dots (QDs) are efficient organic photoredox catalysts due to their high extinction coefficients and easily tunable band edge potentials. Despite the majority of the surface being covered by ligands, our understanding of the effect of the ligand shell on organic photocatalysis is limited to steric effects. We hypothesize that we can increase the activity of QD photocatalysts by designing a ligand shell with targeted electronic properties, namely, redox-mediating ligands. Herein, we functionalize our QDs with hole-mediating ferrocene (Fc) derivative ligands and perform a reaction where the slow step is hole transfer from QD to substrate. Surprisingly, we find that a hole-shuttling Fc inhibits catalysis, but confers much greater stability to the catalyst by preventing a build-up of destructive holes. We also find that dynamically bound Fc ligands can promote catalysis by surface exchange and creation of a more permeable ligand shell. Finally, we find that trapping the electron on a ligand dramatically increases the rate of reaction. These results have major implications for understanding the rate-limiting processes for charge transfer from QDs and the role of the ligand shell in modulating it.
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Affiliation(s)
- Florence Y Dou
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Samantha M Harvey
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Konstantina G Mason
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Micaela K Homer
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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Homer MK, Kuo DY, Dou FY, Cossairt BM. Photoinduced Charge Transfer from Quantum Dots Measured by Cyclic Voltammetry. J Am Chem Soc 2022; 144:14226-14234. [PMID: 35897128 DOI: 10.1021/jacs.2c04991] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Measuring and modulating charge-transfer processes at quantum dot interfaces are crucial steps in developing quantum dots as photocatalysts. In this work, cyclic voltammetry under illumination is demonstrated to measure the rate of photoinduced charge transfer from CdS quantum dots by directly probing the changing oxidation states of a library of molecular charge acceptors, including both hole and electron acceptors. The voltammetry data demonstrate the presence of long-lived charge donor states generated by native photodoping of the quantum dots as well as a positive correlation between driving force and rate of charge transfer. Changes to the voltammograms under illumination follow mechanistic predictions from the ErCi' zone diagram, and electrochemical modeling allows for measurement of the rate of productive electron transfer. Observed rates for photoinduced charge transfer are on the order of 0.1 s-1, which are distinct from the picosecond dynamics measured by conventional transient optical spectroscopy methods and are more closely connected to the quantum yield of light-mediated chemical transformations.
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Affiliation(s)
- Micaela K Homer
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Ding-Yuan Kuo
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Florence Y Dou
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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