| 1. |
- Ghosh, Sirina, et al.
(author)
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Effect of the change of heteroatom on phenyl capped benzazole : Photophysical and electrochemical properties from the structural viewpoint
- 2018
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In: Journal of Luminescence. - : ELSEVIER SCIENCE BV. - 0022-2313 .- 1872-7883. ; 194, s. 164-169
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Journal article (peer-reviewed)abstract
- Donor-acceptor-donor type phenyl capped benzazoles were synthesized and their photophysical properties were studied. By changing the heteroatom (N, O, S and Se) of central acceptor benzazole unit, the emission color was varied from blue to green. Phenyl capped benzotriazole (1) and benzooxadiazole (2) were characterized by single crystal X-ray crystallography. The absolute solid state fluorescence quantum yields of these compounds were obtained in the range of 0.05-0.93 by a calibrated integrating sphere method. High solid state quantum yield can be attributed to the non-planarity and absence of strong intermolecular interactions in the solid state. Except phenyl capped benzotriazole (1), all compounds showed reversible reduction peak in cyclic voltammetry experiments which reflects the considerable n-type nature.
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| 2. |
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| 3. |
- Huang, Jing, et al.
(author)
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Covalently linking CuInS2 quantum dots with a Re catalyst by click reaction for photocatalytic CO2 reduction
- 2018
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:31, s. 10775-10783
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Journal article (peer-reviewed)abstract
- Covalently linking photosensitizers and catalysts in an inorganic-organic hybrid photocatalytic system is beneficial for efficient electron transfer between these components. However, general and straightforward methods to covalently attach molecular catalysts on the surface of inorganic semiconductors are rare. In this work, a classic rhenium bipyridine complex (Re catalyst) has been successfully covalently linked to the low toxicity CuInS2 quantum dots (QDs) by click reaction for photocatalytic CO2 reduction. Covalent bonding between the CuInS2 QDs and the Re catalyst in the QD-Re hybrid system is confirmed by UV-visible absorption spectroscopy, Fourier-transform infrared spectroscopy and energy-dispersive X-ray measurements. Time-correlated single photon counting and ultrafast time-resolved infrared spectroscopy provide evidence for rapid photo-induced electron transfer from the QDs to the Re catalyst. Upon photo-excitation of the QDs, the singly reduced Re catalyst is formed within 300 fs. Notably, the amount of reduced Re in the linked hybrid system is more than that in a sample where the QDs and the Re catalyst are simply mixed, suggesting that the covalent linkage between the CuInS2 QDs and the Re catalyst indeed facilitates electron transfer from the QDs to the Re catalyst. Such an ultrafast electron transfer in the covalently linked CuInS2 QD-Re hybrid system leads to enhanced photocatalytic activity for CO2 reduction, as compared to the conventional mixture of the QDs and the Re catalyst.
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| 4. |
- Pati, Palas Baran, et al.
(author)
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An experimental and theoretical study of an efficient polymer nano-photocatalyst for hydrogen evolution
- 2017
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In: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 10:6, s. 1372-1376
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Journal article (peer-reviewed)abstract
- In this work, we report a highly efficient organic polymer nano-photocatalyst for light driven proton reduction. The system renders an initial rate of hydrogen evolution up to 50 +/- 0.5 mmol g(-1) h(-1), which is the fastest rate among all other reported organic photocatalysts. We also experimentally and theoretically prove that the nitrogen centre of the benzothiadiazole unit plays a crucial role in the photocatalysis and that the Pdots structure holds a close to ideal geometry to enhance the photocatalysis.
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| 5. |
- Pati, Palas Baran
(author)
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Benzazole (B, N, O, S, Se and Te) based D-A-D type oligomers : Switch from electropolymerization to structural aspect
- 2016
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In: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 38, s. 97-106
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Research review (peer-reviewed)abstract
- Conjugated polymers are gaining interest because of their potential application in organic electronic devices such as organic solar cells (OSCs), organic field effect transistors (OFETs) and organic light emitting diods (OLEDs). In order to introduce high perform polymers, planarity for high conjugation and absorption in the full solar spectrum are essential criteria. To tune the optical and elecctrochemical properties of polymer, one of the potential approach is introduction of donor-acceptor (D-A) approach where electron rich moieties (Donor) and electron-withdrawing units (Acceptor) are alternatively arranged. Organic heterols such as pyrrole, furan, thiophene, selenophene are extensively used as donor and benzotriazole, benzooxadiazole, benzothiadiazole and benzoselenadiazole are used as conventional acceptor. In the first section of this review the discussion will be coincised into the donor-acceptor-donor (D-A-D) type oligomers and their electropolymerization to develop D-A polymers. The later part of review deals with the advancement in the study, with only D-A-D type oligomers through their structural and interaction property to understand the packing pattern in solid state. Further reports on the application of these oligomers in molecular devices such as FET and sensors are also discussed. (C) 2016 Elsevier B.V. All rights reserved.
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| 6. |
- Pati, Palas Baran, et al.
(author)
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Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices
- 2017
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 10:11, s. 2480-2495
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Journal article (peer-reviewed)abstract
- A covalently-linked organic dye-cobaloxime catalyst system is developed by facile click reaction for mechanistic studies and application in a dye sensitized solar fuel device based on mesoporous NiO. This system has been systematically investigated by photophysical measurements, density functional theory, time resolved fluorescence, transient absorption spectroscopy as well as photoelectron spectroscopy. The results show that irradiation of the dye-catalyst on NiO leads to ultrafast hole injection into NiO from the excited dye, followed by a fast electron transfer to reduce the catalyst unit. Moreover, they suggest that the dye undergoes structural changes in the excited state and that excitation energy transfer occurs between neighboring molecules. The photoelectrochemical experiments also show the hydrogen production by this system-based NiO photocathode. The axial chloride ligands of the catalyst are released during photocatalysis to create the active sites for proton reduction. A working mechanism of the dye-catalyst on photocathode is eventually proposed on the basis of this study.
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| 7. |
- Pati, Palas Baran, et al.
(author)
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Molecular Triad Containing a TEMPO Catalyst Grafted on Mesoporous Indium Tin Oxide as a Photoelectrocatalytic Anode for Visible Light-Driven Alcohol Oxidation
- 2021
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In: ChemSusChem. - : John Wiley & Sons. - 1864-5631 .- 1864-564X. ; 14:14, s. 2902-2913
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Journal article (peer-reviewed)abstract
- Photoelectrochemical cells based on semiconductors are among the most studied methods of artificial photosynthesis. This study concerns the immobilization, on a mesoporous conducting indium tin oxide electrode (nano-ITO), of a molecular triad (NDADI-P-Ru-TEMPO) composed of a ruthenium tris-bipyridine complex (Ru) as photosensitizer, connected at one end to 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) as alcohol oxidation catalyst and at the other end to the electron acceptor naphthalenedicarboxyanhydride dicarboximide (NDADI). Light irradiation of NDADI-P-Ru-TEMPO grafted to nano-ITO in a pH 10 carbonate buffer effects selective oxidation of para-methoxybenzyl alcohol (MeO-BA) to para-methoxybenzaldehyde with a TON of approximately 150 after 1 h of photolysis at a bias of 0.4 V vs. SCE. The faradaic efficiency is found to be of 80 +/- 5 %. The photophysical study indicates that photoinduced electron transfer from the Ru complex to NDADI is a slow process and must compete with direct electron injection into ITO to have a better performing system. This work sheds light on some of the important ways to design more efficient molecular systems for the preparation of photoelectrocatalytic cells based on catalyst-dye-acceptor arrays immobilized on conducting electrodes.
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| 8. |
- Pati, Palas Baran, et al.
(author)
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New dyes for DSSC containing triphenylamine based extended donor : Synthesis, photophysical properties and device performance
- 2017
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In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 1873-3557. ; 178, s. 106-113
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Journal article (peer-reviewed)abstract
- Three new triphenylamine based dyes with Donor-Donor-Spacer-Acceptor (D-D-n-A) arrangement were designed and synthesized by convenient synthetic pathway. Unsymmetrical extended donor part may help to reduce the aggregation of dyes on the semiconductor surface. Wide range of absorption in the visible spectrum, electrochemical studies and theoretical optimization suggest that these dyes can be good members for DSSC. Further to check the performance of these dyes in device the solar cells were developed using iodine free Co-based electrolyte. Electronic characterisation concludes that devices based on 136 have the highest power conversion efficiency (4.7%) mostly due to an improved electron lifetime, which therefore improves both the Voc and Jac of the devices.
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| 9. |
- Pati, Palas Baran
(author)
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Organic chemodosimeter for cyanide : A nucleophilic approach
- 2016
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In: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 222, s. 374-390
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Journal article (peer-reviewed)abstract
- Out of the all anions cyanide is one of the most threaten for environmental and social system and abundance of cyanide in environment generate not only from industrial waste but also from the biological process of fungal and algae. It has very much toxic effect, after a certain limit it may cause to death. The interest for qualitative and quantitative detection of cyanide is growing on. Detection rely on the change in absorption and emission properties of probe upon binding with cyanide is important because of its simple analysis technique. Cyanide is a good nucleophile and this property can be very much useful to develop organic probes to detect its presence. Here this review deals with the organic chemodosimetric probes for cyanide, more specifically the detection mechanism is driven by the nucleophilic attack of cyanide ion to the probe. Discussed organic probes are divided into some classes according to their structural features and functional group present in the probe.
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| 10. |
- Tian, Lei, et al.
(author)
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Mechanistic Insights into Solid-State p-Type Dye-Sensitized Solar Cells
- 2019
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:43, s. 26151-26160
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Journal article (peer-reviewed)abstract
- The study of p-type dye sensitized solar cells (p-DSCs) is appealing but challenging. Although the devices have been studied for 20 years, the light conversion efficiency lags far behind those of n-DSCs. Very recently, on the basis of a core-shell structure, a novel solid-state p-DSC (p-ssDSCs) has been fabricated, which showed great enhancement in open-circuit voltage and dye regeneration rate. To further improve the performance of such devices, charge diffusion, recombination process, and the main limiting factors have to be understood. In the present paper, core-shell p-ssDSCs with ZnO as an electron conductor were fabricated by atomic layer deposition. The charge transport time was determined to be ca. 0.1 ms, which is about 2 orders of magnitude faster than those of typical liquid devices with I-/I-3(-) as a redox mediator. As a consequence, the devices exhibit the highest reported charge diffusion coefficient (D-d)' among p-DSCs. It is ascribed to an electron-limiting diffusion process by the ambipolar diffusion model, suggesting a different charge-transport-determining mechanism in contrast to liquid p-DSCs. The charge recombination rate is 1-2 orders of magnitude slower than its charge transport time, mandating that the estimated charge collection efficiency is near unity. Detailed analysis of the incident photon-to-electron conversion efficiency suggests that the energy conversion efficiency in these p-ssDSCs is currently limited by a large fraction of dyes that is not fully electrically connected in the device.
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