Publications
ResearcherID : C-5956-2008 (TY, h-index: 24) , AAZ-8749-2021 (RK, h-index: 11)
Google Scholar : TY (h-index: 34), RK (h-index: 11)
2020
Takashi Yatsui, Yuki Nakamura, Yosuke Suzuki, Tatsuki Morimoto, Yuma Kato, Muneaki Yamamoto, Tomoko Yoshida, Wataru Kurashige, Nobuyuki Shimizu, Yuichi Negishi, Kenji Iida, Katsuyuki Nobusada
Increase in CO2 reduction rate via optical near-field effect Journal Article
In: Journal of Nanophotonics, vol. 14, no. 4, pp. 046011, 2020.
Abstract | Links | BibTeX | Tags: CO2 reduction, Near-field effect
@article{CO2reduction,
title = {Increase in CO2 reduction rate via optical near-field effect},
author = {Takashi Yatsui and Yuki Nakamura and Yosuke Suzuki and Tatsuki Morimoto and Yuma Kato and Muneaki Yamamoto and Tomoko Yoshida and Wataru Kurashige and Nobuyuki Shimizu and Yuichi Negishi and Kenji Iida and Katsuyuki Nobusada},
doi = {10.1117/1.JNP.14.046011},
year = {2020},
date = {2020-11-27},
journal = {Journal of Nanophotonics},
volume = {14},
number = {4},
pages = {046011},
abstract = {To reduce the effects of global warming, visible and near-infrared light must be used more efficiently. Deep ultraviolet light (8 eV) is required for the direct dissociation of CO2 by light; however, the introduction of a metal complex has made it possible to realize CO2 reduction with visible light. We demonstrate that the optical near field (ONF) can increase the CO2 reduction rate. For this, we used gold clusters, because they can be a suitable source for ONFs, as their size and density can be controlled by the number of gold atoms. By attaching a metal complex near gold clusters with diameters of 1.0 to 1.3 nm, we confirm that the reduction rate of CO2 to CO increased by 1.5 to 2.1 times. The gold clusters were sufficiently small; therefore, there was no plasmonic resonant peak or heat generation. Because the near-field effect is based on a photochemical reaction, it can be applied to other metal complexes used in CO2 reduction, and it has other applications such as water splitting and water purification.},
keywords = {CO2 reduction, Near-field effect},
pubstate = {published},
tppubtype = {article}
}
To reduce the effects of global warming, visible and near-infrared light must be used more efficiently. Deep ultraviolet light (8 eV) is required for the direct dissociation of CO2 by light; however, the introduction of a metal complex has made it possible to realize CO2 reduction with visible light. We demonstrate that the optical near field (ONF) can increase the CO2 reduction rate. For this, we used gold clusters, because they can be a suitable source for ONFs, as their size and density can be controlled by the number of gold atoms. By attaching a metal complex near gold clusters with diameters of 1.0 to 1.3 nm, we confirm that the reduction rate of CO2 to CO increased by 1.5 to 2.1 times. The gold clusters were sufficiently small; therefore, there was no plasmonic resonant peak or heat generation. Because the near-field effect is based on a photochemical reaction, it can be applied to other metal complexes used in CO2 reduction, and it has other applications such as water splitting and water purification.
2019
Takashi Yatsui, Yusuke Nakahira, Yuki Nakamura, Tatsuki Morimoto, Yuma Kato, Muneaki Yamamoto, Tomoko Yoshida, Kenji Iida, Katsuyuki Nobusada
Realization of red shift of absorption spectra using optical near-field effect Journal Article
In: Nanotechnology, vol. 30, no. 34, pp. 34LT02, 2019.
Abstract | Links | BibTeX | Tags: CO2 reduction, First, Near-field effect
@article{Yatsui_2019,
title = {Realization of red shift of absorption spectra using optical near-field effect},
author = {Takashi Yatsui and Yusuke Nakahira and Yuki Nakamura and Tatsuki Morimoto and Yuma Kato and Muneaki Yamamoto and Tomoko Yoshida and Kenji Iida and Katsuyuki Nobusada},
doi = {10.1088/1361-6528/ab2092},
year = {2019},
date = {2019-06-01},
journal = {Nanotechnology},
volume = {30},
number = {34},
pages = {34LT02},
publisher = {IOP Publishing},
abstract = {In many applications such as CO2 reduction and water splitting, high-energy photons in the ultraviolet region are required to complete the chemical reactions. However, to realize sustainable development, the photon energies utilized must be lower than the absorption edge of the materials including the metal complex for CO2 reduction, the electrodes for water splitting, because of the huge amount of lower energy than the visible region received from the sun. In the previous works, we had demonstrated that optical near-fields (ONFs) could realize chemical reactions, by utilizing photon energies much lower than the absorption edge because of the spatial non-uniformity of the electric field. In this paper, we demonstrate that an ONF can realize the red shift of the absorption spectra of the metal-complex material for photocatalytic reduction. By attaching the metal complex to ZnO nano-crystalline aggregates with nano-scale protrusions, the absorption spectra by using diffuse reflection of the metal complex can be shifted to a longer wavelength by 10.6 nm. The results of computational studies based on a first-principles computational program including the ONF effect provide proof of the increase in the absorption of the metal complex at lower photon energies. Since the near-field assisted field increase improves the carrier excitation in the metal-complex materials, this effect may be universal and it could applicable to CO2 reduction using the other metal-complex materials, as well as to the other photo excitation process including water splitting.},
keywords = {CO2 reduction, First, Near-field effect},
pubstate = {published},
tppubtype = {article}
}
In many applications such as CO2 reduction and water splitting, high-energy photons in the ultraviolet region are required to complete the chemical reactions. However, to realize sustainable development, the photon energies utilized must be lower than the absorption edge of the materials including the metal complex for CO2 reduction, the electrodes for water splitting, because of the huge amount of lower energy than the visible region received from the sun. In the previous works, we had demonstrated that optical near-fields (ONFs) could realize chemical reactions, by utilizing photon energies much lower than the absorption edge because of the spatial non-uniformity of the electric field. In this paper, we demonstrate that an ONF can realize the red shift of the absorption spectra of the metal-complex material for photocatalytic reduction. By attaching the metal complex to ZnO nano-crystalline aggregates with nano-scale protrusions, the absorption spectra by using diffuse reflection of the metal complex can be shifted to a longer wavelength by 10.6 nm. The results of computational studies based on a first-principles computational program including the ONF effect provide proof of the increase in the absorption of the metal complex at lower photon energies. Since the near-field assisted field increase improves the carrier excitation in the metal-complex materials, this effect may be universal and it could applicable to CO2 reduction using the other metal-complex materials, as well as to the other photo excitation process including water splitting.
2013
Nabila Tanjeem, Tadashi Kawazoe, Takashi Yatsui
CO2 phonon mode renormalization using phonon-assisted energy up-conversion Journal Article
In: Scientific Reports, vol. 3, pp. 3341, 2013.
Abstract | Links | BibTeX | Tags: CO2 reduction, Non-uniform optical near field
@article{2013nabilaSR,
title = {CO2 phonon mode renormalization using phonon-assisted energy up-conversion},
author = {Nabila Tanjeem and Tadashi Kawazoe and Takashi Yatsui},
doi = {10.1038/srep03341},
year = {2013},
date = {2013-11-01},
journal = {Scientific Reports},
volume = {3},
pages = {3341},
publisher = {Springer Nature},
abstract = {Molecular dissociation under incident light whose energy is lower than the bond dissociation energy has been achieved through multi step excitation using a coupled state of a photon, electron and multimode-coherent phonon as known as the dressed photon phonon (DPP). Here, we have investigated the effects of the DPP on CO2, a very stable molecule with high absorption and dissociation energies, by introducing ZnO nanorods to generate the DPP. Then, the changes in CO2 absorption bands were evaluated using light with a wavelength longer than the absorption wavelength, which confirmed the DPP-assisted energy up-conversion. To evaluate the specific CO2 modes related to this process, we measured the CO2 vibration-rotation spectra in the near-infrared region. Detailed analysis of the 3ν3 vibrational band when a DPP source is present showed that DPP causes a significant increase in the intensity of certain absorption bands, especially those that require higher energies to activate.},
keywords = {CO2 reduction, Non-uniform optical near field},
pubstate = {published},
tppubtype = {article}
}
Molecular dissociation under incident light whose energy is lower than the bond dissociation energy has been achieved through multi step excitation using a coupled state of a photon, electron and multimode-coherent phonon as known as the dressed photon phonon (DPP). Here, we have investigated the effects of the DPP on CO2, a very stable molecule with high absorption and dissociation energies, by introducing ZnO nanorods to generate the DPP. Then, the changes in CO2 absorption bands were evaluated using light with a wavelength longer than the absorption wavelength, which confirmed the DPP-assisted energy up-conversion. To evaluate the specific CO2 modes related to this process, we measured the CO2 vibration-rotation spectra in the near-infrared region. Detailed analysis of the 3ν3 vibrational band when a DPP source is present showed that DPP causes a significant increase in the intensity of certain absorption bands, especially those that require higher energies to activate.