Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots
Abstract CuAlS2/ZnS Quantum dots (QDs) are known to directly convert aqueous solutions of bicarbonate ions to oxygen and organic molecules such as formate with a remarkable efficiency even under sunlight. In cases, fairly complicated organic reaction products such as acetate and methanol have been o...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley-VCH
2021-05-01
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| Series: | Nano Select |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/nano.202000219 |
| _version_ | 1818620281970753536 |
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| author | Arpita Mukherjee Pranab Dutta Biswajit Bhattacharyya Guru Pratheep Rajasekar Amit Kumar Simlandy Anshu Pandey |
| author_facet | Arpita Mukherjee Pranab Dutta Biswajit Bhattacharyya Guru Pratheep Rajasekar Amit Kumar Simlandy Anshu Pandey |
| author_sort | Arpita Mukherjee |
| collection | DOAJ |
| description | Abstract CuAlS2/ZnS Quantum dots (QDs) are known to directly convert aqueous solutions of bicarbonate ions to oxygen and organic molecules such as formate with a remarkable efficiency even under sunlight. In cases, fairly complicated organic reaction products such as acetate and methanol have been observed when reactions are allowed to continue for longer periods of time. Here, we investigate the electron dynamics that occurs within CuAlS2/ZnS QDs and show that it is essentially dominated by ultrafast electron transfer (560 fs for 0.4 excitons per dot) to the surface. The electron dwell time in the conduction band increases exponentially (for example 872 fs for 1.4 excitons per dot) with the excitation fluence. This is reverse of the auger limited response of conventional QDs and is hypothesized to exhibit strong charge separation that lies at the root of the remarkable photocatalytic activity. We further investigate this system through multi‐pump experiments. We find that the system response to prior excitation changes over the period of nanoseconds, consistent with the charge reorganization in the system, well after the initial electron transfer. The results of these experiments are summarized in terms of a coulomb‐well interpretation. |
| first_indexed | 2024-12-16T17:50:54Z |
| format | Article |
| id | doaj.art-f13f57e0fe1c4b50b94838c18c926b71 |
| institution | Directory Open Access Journal |
| issn | 2688-4011 |
| language | English |
| last_indexed | 2024-12-16T17:50:54Z |
| publishDate | 2021-05-01 |
| publisher | Wiley-VCH |
| record_format | Article |
| series | Nano Select |
| spelling | doaj.art-f13f57e0fe1c4b50b94838c18c926b712022-12-21T22:22:19ZengWiley-VCHNano Select2688-40112021-05-012595896610.1002/nano.202000219Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dotsArpita Mukherjee0Pranab Dutta1Biswajit Bhattacharyya2Guru Pratheep Rajasekar3Amit Kumar Simlandy4Anshu Pandey5Indian Institute of Science Solid State and Structural Chemistry Unit Bangalore 560012 IndiaIndian Institute of Science Solid State and Structural Chemistry Unit Bangalore 560012 IndiaIndian Institute of Science Solid State and Structural Chemistry Unit Bangalore 560012 IndiaIndian Institute of Science Solid State and Structural Chemistry Unit Bangalore 560012 IndiaDepartment of Organic Chemistry Indian Institute of Science Bangalore 560012 IndiaIndian Institute of Science Solid State and Structural Chemistry Unit Bangalore 560012 IndiaAbstract CuAlS2/ZnS Quantum dots (QDs) are known to directly convert aqueous solutions of bicarbonate ions to oxygen and organic molecules such as formate with a remarkable efficiency even under sunlight. In cases, fairly complicated organic reaction products such as acetate and methanol have been observed when reactions are allowed to continue for longer periods of time. Here, we investigate the electron dynamics that occurs within CuAlS2/ZnS QDs and show that it is essentially dominated by ultrafast electron transfer (560 fs for 0.4 excitons per dot) to the surface. The electron dwell time in the conduction band increases exponentially (for example 872 fs for 1.4 excitons per dot) with the excitation fluence. This is reverse of the auger limited response of conventional QDs and is hypothesized to exhibit strong charge separation that lies at the root of the remarkable photocatalytic activity. We further investigate this system through multi‐pump experiments. We find that the system response to prior excitation changes over the period of nanoseconds, consistent with the charge reorganization in the system, well after the initial electron transfer. The results of these experiments are summarized in terms of a coulomb‐well interpretation.https://doi.org/10.1002/nano.202000219charge separationCuAlS2photocatalysisultrafast electron transfer |
| spellingShingle | Arpita Mukherjee Pranab Dutta Biswajit Bhattacharyya Guru Pratheep Rajasekar Amit Kumar Simlandy Anshu Pandey Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots Nano Select charge separation CuAlS2 photocatalysis ultrafast electron transfer |
| title | Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots |
| title_full | Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots |
| title_fullStr | Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots |
| title_full_unstemmed | Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots |
| title_short | Ultrafast spectroscopic investigation of the artificial photosynthetic activity of CuAlS2/ZnS quantum dots |
| title_sort | ultrafast spectroscopic investigation of the artificial photosynthetic activity of cuals2 zns quantum dots |
| topic | charge separation CuAlS2 photocatalysis ultrafast electron transfer |
| url | https://doi.org/10.1002/nano.202000219 |
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