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Ji, Y., Fan, T. & Luo, Y. (2020). First-principles study on the mechanism of photocatalytic reduction of nitrobenzene on the rutile TiO2(110) surface. Physical Chemistry, Chemical Physics - PCCP, 22(3), 1187-1193
Open this publication in new window or tab >>First-principles study on the mechanism of photocatalytic reduction of nitrobenzene on the rutile TiO2(110) surface
2020 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 3, p. 1187-1193Article in journal (Refereed) Published
Abstract [en]

Photocatalytic synthesis of organic compounds has attracted more and more attention recently. In this work, we present a theoretical study on the molecular mechanism of the photocatalytic reduction of nitrobenzene to aniline on the rutile TiO2(110) surface. We have studied the adsorption and conversion of nitrobenzene at both the surface Ti site and the oxygen vacancy (O-v) site. The full reaction pathways at these two sites were calculated. The rate-limiting step and possible intermediates were identified. The results suggest that O-v is more active in the adsorption and conversion of nitrobenzene. Interestingly, we found that the chemistry of nitrobenzene on the rutile TiO2(110) surface, especially the breaking of the N-O bond, is closely related to the number of excess electrons available. Based on the calculation, we have proposed a full molecular mechanism which is compatible with the existing experiments. The results should be helpful for the design of more efficient photocatalysts for the conversion of nitrobenzene.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2020
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-267745 (URN)10.1039/c9cp05010h (DOI)000509371400025 ()31848529 (PubMedID)2-s2.0-85078354360 (Scopus ID)
Note

QC 20200218

Available from: 2020-02-18 Created: 2020-02-18 Last updated: 2020-02-18Bibliographically approved
Chen, T., Luo, Y. & Li, A. (2020). Fragmentation and isomerization of polycyclic aromatic hydrocarbons in the interstellar medium: Coronene as a case study. Astronomy and Astrophysics, 633, Article ID A103.
Open this publication in new window or tab >>Fragmentation and isomerization of polycyclic aromatic hydrocarbons in the interstellar medium: Coronene as a case study
2020 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 633, article id A103Article in journal (Refereed) Published
Abstract [en]

Aims. Due to the limitations of current computational technology, the fragmentation and isomerization products of vibrationally-excited polycyclic aromatic hydrocarbon (PAH) molecules and their derivatives have been poorly studied. In this work, we investigate the intermediate products of PAHs and their derivatives as well as the gas-phase reactions relevant to the interstellar medium, with coronene as a case study. Methods. Based on the semi-empirical method of PM3 as implemented in the CP2K program, molecular dynamics simulations were performed to model the major processes (e.g., vibrations, fragmentations, and isomerizations) of coronene and its derivatives (e.g., methylated coronene, hydrogenated coronene, dehydrogenated coronene, nitrogen-substituted coronene, and oxygen-substituted coronene) at temperatures of 3000 K and 4000 K. Results. We find that the anharmonic effects are crucial for the simulation of vibrational excitation. For the molecules studied here, H-2, CO, HCN, and CH2 are the major fragments. Following the dissociation of these small units, most of the molecules could maintain their ring structures, but a few molecules would completely break into carbon chains. The transformation from a hexagon to a pentagon or a heptagon may occur and the heteroatomic substitutions (e.g., N- or O-substitutions) would facilitate the transformation.

Place, publisher, year, edition, pages
EDP SCIENCES S A, 2020
Keywords
astrochemistry, molecular data, molecular processes, ISM: molecules, methods: laboratory: molecular, photon-dominated region
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-267153 (URN)10.1051/0004-6361/201936873 (DOI)000508201200001 ()
Note

QC 20200217

Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17Bibliographically approved
Ji, Y. & Luo, Y. (2019). Direct Donation of Protons from H2O to CO2 in Artificial Photosynthesis on the Anatase TiO2(101) Surface. The Journal of Physical Chemistry C, 123(5), 3019-3023
Open this publication in new window or tab >>Direct Donation of Protons from H2O to CO2 in Artificial Photosynthesis on the Anatase TiO2(101) Surface
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 5, p. 3019-3023Article in journal (Refereed) Published
Abstract [en]

Conversion of CO2 and H2O into value-added organic molecules via artificial photosynthesis is a promising solution to current energy and environment problems. In the reaction, it is generally believed that CO2 is converted into organic molecules by photogenerated electrons and protons that result from photo-oxidation of H2O. In this work, we investigate the possibility that H2O, without being oxidized, directly donates protons to CO2 and other intermediates adsorbed at the oxygen vacancy on the anatase TiO2(101) surface. We found that this can greatly lower the barriers (by about 0.3 eV) for the hydrogenation of CO2, CO, H2CO, and CH3O because less energy is required to displace these adsorbates to accept the proton (in H2O). The OH- group produced in these reactions can recombine with a surface-adsorbed proton to form a new H2O molecule, making H2O a shuttling center of the adsorbed protons, or it can take part in the oxygen evolution reaction with a lower barrier. The results suggest that H2O can play multiple roles in artificial photosynthesis and the reduction and oxidation parts of the reaction may have synergistic effects.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-245143 (URN)10.1021/acs.jpcc.8b11936 (DOI)000458348600035 ()2-s2.0-85061325805 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Chen, T. & Luo, Y. (2019). Formation of polyynes and ring-polyyne molecules following fragmentation of polycyclic aromatic hydrocarbons. Monthly notices of the Royal Astronomical Society, 486(2), 1875-1881
Open this publication in new window or tab >>Formation of polyynes and ring-polyyne molecules following fragmentation of polycyclic aromatic hydrocarbons
2019 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 486, no 2, p. 1875-1881Article in journal (Refereed) Published
Abstract [en]

In this work, we perform molecular dynamic (MD) simulations to investigate the stability and fragmentation processes of vibrationally excited linear polycyclic aromatic hydrocarbons (PAHs). The program of CP2K in combination with the semi-empirical method PM3 is utilized for the MD simulations. The simulations show that the formation of molecular hydrogens (H-2) is different than previous studies, in particular, different than compact PAHs. At high temperatures, linear PAHs tend to open aromatic rings and convert the sp(3) C-C or sp(2) C=C bonds to sp C C bonds by removing H-2; i.e. polyynes are formed in such process. Besides polyynes, PAHs attached with sp-bonded polyyne chains are commonly observed at high temperatures. We notice that due to the addition of flexible tails (polyynes), the ring-polyyne molecules do not dissociate for a long period of time at high temperatures. Such structures facilitate the molecules to survive in the harsh environment of the interstellar medium. In addition, the ring-polyyne structures induce dipole moments that could, in principle, be detected by radio astronomy.

Place, publisher, year, edition, pages
OXFORD UNIV PRESS, 2019
Keywords
astrochemistry, molecular processes, methods: laboratory: molecular, ISM: molecules, photodissociation region (PDR)
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-255492 (URN)10.1093/mnras/stz1014 (DOI)000474899400033 ()2-s2.0-85067965367 (Scopus ID)
Note

QC 20190918

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-09-18Bibliographically approved
Ma, Y., Lin, J., Song, X.-N. -., Wang, C.-K. -., Hua, W. & Luo, Y. (2019). Local structures of nitrogen doped graphdiynes determined by computational X-ray spectroscopy. Carbon, 149, 672-678
Open this publication in new window or tab >>Local structures of nitrogen doped graphdiynes determined by computational X-ray spectroscopy
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2019 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 149, p. 672-678Article in journal (Refereed) Published
Abstract [en]

Nitrogen doping is an important method to modulate electronic structure of two-dimensional carbon materials. The properties of the doped systems are heavily dependent on the local structure of nitrogen dopants involved, which are often determined by experimental X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) at the nitrogen K-edge. In the present work, the N1s XPS and NEXAFS spectra of nitrogen-doped graphdiynes have been accurately calculated at the density functional theory level. Five representative nitrogen-dopants in graphdiynes, namely [pyridinic, amino, graphitic, and two sp-hybridized N (sp-N-1 and sp-N-2) local structures], are fully examined, from which all experimental features could be correctly assigned. The calculated results can be used to determine the ratio of different nitrogen dopants in graphdiyne at different elevated temperatures reported in previous experiments. Our findings provide the basic references for structure determination of nitrogen doped graphdiyne and new understanding of the underlying structure-property relationships.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Density functional calculation, Graphdiyne, Near-edge X-ray absorption fine-structure spectroscopy, Nitrogen-doping, X-ray photoelectron spectroscopy, Computation theory, Density functional theory, Doping (additives), Electronic structure, Photoelectron spectroscopy, Photoelectrons, Photons, X ray absorption, X ray absorption near edge structure spectroscopy, X ray photoelectron spectroscopy, Elevated temperature, Local structure, Near edge x ray absorption fine structure, Structure determination, Structure property relationships, X ray photoelectron spectra, Nitrogen
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-252490 (URN)10.1016/j.carbon.2019.04.045 (DOI)000471602000075 ()2-s2.0-85065060311 (Scopus ID)
Note

QC 20190712

Available from: 2019-07-12 Created: 2019-07-12 Last updated: 2019-07-29Bibliographically approved
Xie, Z., Duan, S., Wang, C.-K. & Luo, Y. (2019). Monitoring Hydrogen/Deuterium Tautomerization in Transient Isomers of Single Porphine by Highly Localized Plasmonic Field. The Journal of Physical Chemistry C, 123(17), 11081-11093
Open this publication in new window or tab >>Monitoring Hydrogen/Deuterium Tautomerization in Transient Isomers of Single Porphine by Highly Localized Plasmonic Field
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 17, p. 11081-11093Article in journal (Refereed) Published
Abstract [en]

Inner proton transfer between two trans isomers (tautomerization) in porphyrins plays a crucial role in many biological systems as well as molecular nanotechnology. Although the stepwise mechanism of tautomerization is well accepted, the involved intermediate cis-isomer has not been directly detected owing to its short lifetime and the extremely low intensities of corresponding hydrogen vibrations. Here, taking a single porphine as the prototype, we theoretically demonstrate that Raman intensities of the hydrogen vibrations become accessible under the highly localized plasmonic field because of the symmetry breaking effect. In addition, with the ultrafast incident excitations, we find that Raman signals of cis-porphine could be distinguished from the stable trans isomer, suggesting a general protocol for the direct characterization of transient isomers. Moreover, calculated results reveal that the position of inner hydrogen/deuterium can be unambiguously visualized from Raman images of the corresponding stretching modes, providing a unique optical means for the chemical monitoring of tautomerization in porphine and its derivatives.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-252384 (URN)10.1021/acs.jpcc.9b00398 (DOI)000466988600040 ()2-s2.0-85065302261 (Scopus ID)
Note

QC 20190618

Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2019-11-07Bibliographically approved
Li, X., Duan, S., Liu, H., Chen, G., Luo, Y. & Ågren, H. (2019). On the Mechanism for the Extremely Efficient Sensitization of Yb3+ Luminescence in CsPbCl3 Nanocrystals. Journal of Physical Chemistry Letters, 10(3), 487-492
Open this publication in new window or tab >>On the Mechanism for the Extremely Efficient Sensitization of Yb3+ Luminescence in CsPbCl3 Nanocrystals
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 3, p. 487-492Article in journal (Refereed) Published
Abstract [en]

Rare earth ion (RE3+)-doped inorganic CsPbX3 (X = Cl or Cl/Br) nanocrystals have been presented as promising materials for applications in solar-energy conversion technology. An extremely efficient sensitization of Yb3+ luminescence in CsPbCl3 nanoparticles (NCs) was very recently demonstrated where quantum cutting is responsible for the performance of photoluminescence quantum yields over 100% (T. J. Milstein, et al. Nano Letters 2018, 18, 3792). In the present work, based on the cubic phase of inorganic perovskite, we seek to obtain atom-level insight into the basic mechanisms behind these observations in order to boost the further development of RE3+-doped CsPbX3 NCs for optoelectronics. In our calculations of cubic crystal structure, we do not find any energy level formed in the middle of the band gap, which disfavors a mechanism of stepwise energy transfer from the perovskite host to two Yb3+ ions. Our work indicates that the configuration with "right-angle" Yb3+-V-Pb-Yb3+ couple is most likely to form in Yb3+-doped CsPbCl3. Associated with this "right-angle" couple, the "right-angle" Pb atom with trapped excited states would localize the photogenerated electrons and act as the energy donor in a quantum cutting process, which achieves simultaneous sensitization of two neighboring Yb3+ ions.

National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-246213 (URN)10.1021/acs.jpclett.8b03406 (DOI)000458704800026 ()30642182 (PubMedID)2-s2.0-85061130625 (Scopus ID)
Note

QC 20190318

Available from: 2019-03-16 Created: 2019-03-16 Last updated: 2020-03-09Bibliographically approved
Chen, T., Luo, Y. & Li, A. (2019). The infrared bands of polycyclic aromatic hydrocarbons in the 1.6-1.7 mu m wavelength region. Astronomy and Astrophysics, 632, Article ID A71.
Open this publication in new window or tab >>The infrared bands of polycyclic aromatic hydrocarbons in the 1.6-1.7 mu m wavelength region
2019 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 632, article id A71Article in journal (Refereed) Published
Abstract [en]

Context. The 3.3 mu m aromatic C-H stretching band of polycyclic aromatic hydrocarbon (PAH) molecules seen in a wide variety of astrophysical regions is often accompanied by a series of weak satellite bands at similar to 3.4-3.6 mu m. One of these sources, IRAS 21282 +5050, a planetary nebula, also exhibits a weak band at similar to 1.68 mu m. While the satellite features at similar to 3.4-3.6 mu m are often attributed to the anharmonicities of PAHs, it is not clear whether overtones or combination bands dominate the 1.68 mu m feature. Aims. In this work, we examine the anharmonic spectra of eight PAH molecules, including anthracene, tetracene, pentacene, phenanthrene, chrysene, benz[a]anthracene, pyrene, and perylene, to explore the origin of the infrared bands in the 1.6-1.7 mu m wavelength region. Methods. Density functional theory (DFT) in combination with the vibrational second-order perturbation theory (VPT2) was used to compute the anharmonic spectra of PAHs. To simulate the vibrational excitation process of PAHs, the Wang-Landau random walk technique was employed. Results. All the dominant bands in the 1.6-1.7 mu m wavelength range and in the 3.1-3.5 mu m C-H stretching region are calculated and tabulated. It is demonstrated that combination bands dominate the 1.6-1.7 mu m region, while overtones are rare and weak in this region. We also calculate the intensity ratios of the 3.1-3.5 mu m C-H stretching features to the bands in the 1.6-1.7 mu m region, I3.1-3:5/I1.6-1.7, for both ground and vibrationally excited states. On average, we obtain < I3.1-3.5=/I1.6-1.7 > approximate to 12.6 and < I3.1-3.5=/I1.6-1.7 > approximate to 17:6 for PAHs at ground states and at vibrationally excited states, respectively.

Place, publisher, year, edition, pages
EDP Sciences, 2019
Keywords
astrochemistry, molecular data, ISM: molecules, ISM: lines and bands, infrared: general, molecular processes
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-266730 (URN)10.1051/0004-6361/201936310 (DOI)000505727500001 ()
Note

QC 20200117

Available from: 2020-01-17 Created: 2020-01-17 Last updated: 2020-01-22Bibliographically approved
Hu, W., Cao, X., Zhang, Y., Li, T., Jiang, J. & Luo, Y. (2019). Tunable Single-Photon Emission by Defective Boron-Nitride Nanotubes for High-Precision Force Detection. The Journal of Physical Chemistry C, 123(14), 9624-9628
Open this publication in new window or tab >>Tunable Single-Photon Emission by Defective Boron-Nitride Nanotubes for High-Precision Force Detection
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2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 14, p. 9624-9628Article in journal (Refereed) Published
Abstract [en]

Boron-nitride nanotubes (BNNTs) hold great potential for electronic, optical, and mechanical applications. By introducing a NBVN defect of removing one nitrogen atom while replacing one boron by nitrogen atom, we examined the use of defective NBVN@BNNTs as a novel type of single-photon emission (SPE) material. Using first-principles calculations to reveal the electronic structures of NBVN@BNNTs, we found that SPE with 1.45-2.29 eV energy can be generated in NBVN@BNNTs with size ranging from (5,0) to (10,0). It is also intriguing to find that their SPE responses are sensitive to the external forces, as indicated by the computed potential energy surfaces and dielectric tensors. Specifically, the (7,0) NBVN@BNNT can serve as an ideal force detector due to its sensitivity and linear response to external force. However, the (5,0) and (6,0) NBVN@BNNTs exhibit insensitive SPE with respect to force applied, and the detection ability of the (8,0), (9,0), and (10,0) NBVN@BNNTs are limited due to the emergence of new photon emissions when tensions become larger than 10 nN. These findings would open a new door for utilizing defective BNNTs for SPE and mechanical detection applications.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-251491 (URN)10.1021/acs.jpcc.9b01651 (DOI)000464768600129 ()2-s2.0-85064344387 (Scopus ID)
Note

QC 20190522

Available from: 2019-05-22 Created: 2019-05-22 Last updated: 2019-05-22Bibliographically approved
Li, J., Luo, Y. & Zhang, J. (2018). A theoretical study on vibronic spectra and photo conversation process of protonated naphthalenes. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, 205, 520-527
Open this publication in new window or tab >>A theoretical study on vibronic spectra and photo conversation process of protonated naphthalenes
2018 (English)In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 205, p. 520-527Article in journal (Refereed) Published
Abstract [en]

The equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of alpha-and beta-protonated naphthalenes (alpha-and beta-HN+) have been studied by time -dependent density -functional theory (TD-DFT). Within the Franck -Condon approximation, vibronic absorption spectra of alpha-HN+ and beta-HN+, together with the vibronic emission spectrum of alpha-HN+, have been calculated. The obtained good agreement between the theoretical and experimental spectra enables to correctly assign vibronic features in both absorption and emission spectra. Moreover, the non -radiative deactivation pathway from the low-lying excite states to the ground state in alpha-HN+ and beta-HN+, as well as the photo-induce proton transfer pathway, are investigated at the CASPT2/CASSCF/6-31G* level. Our study is helpful for understanding the photochemical behavior of these important polycyclic aromatic hydrocarbon molecules.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Vibronic spectra, Photo conversation, Theoretical study, Protonated naphthalenes
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-235992 (URN)10.1016/j.saa.2018.07.074 (DOI)000445713600061 ()30071500 (PubMedID)2-s2.0-85050638025 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20181015

Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-01-18Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0007-0394

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