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| 2. |
- Huang, Jing, et al.
(författare)
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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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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:31, s. 10775-10783
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Liu, Aijie, et al.
(författare)
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In Situ Preparation and Immobilization of Semiconducting Polymer Dots on Microbeads for Efficient and Stable Photocatalytic Hydrogen Evolution
- 2021
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:5, s. 4308-4312
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Tidskriftsartikel (refereegranskat)abstract
- Organic semiconducting polymers dots (Pdots) have recently shown efficient photocatalytic activity for hydrogen evolution in an aqueous phase. However, colloidal Pdots face problems of aggregation and precipitation during the photocatalytic reaction due to unavoidable collisions between particles, thus resulting in a short catalytic lifetime. In this work, in situ preparation of PFBT Pdots on the surface of microbeads is reported. Results indicate that, with this facile method and support of a template, the photocatalytic properties of PFBT Pdots can be highly enhanced.
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| 4. |
- Pati, Palas Baran, et al.
(författare)
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An experimental and theoretical study of an efficient polymer nano-photocatalyst for hydrogen evolution
- 2017
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 10:6, s. 1372-1376
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Tidskriftsartikel (refereegranskat)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, et al.
(författare)
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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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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 10:11, s. 2480-2495
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Tian, Haining, 1983-, et al.
(författare)
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Hydrogen evolution by a photoelectrochemical cell based on a Cu2O-ZnO-[FeFe] hydrogenase electrode
- 2018
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Ingår i: Journal of Photochemistry and Photobiology A. - : Elsevier BV. - 1010-6030 .- 1873-2666. ; 366, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- A Cu2O-ZnO-hydrogenase photocathode possessed enzyme/semiconductor junction has been constructed by immobilizing a biological protein catalyst, hydrogenase-CrHydA1 enzyme on the ZnO protected Cu2O electrode. With light illumination, a photocurrent of 0.8 mA/cm2 at 0.15 V vs. RHE was obtained and hydrogen was successfully detected from the photocathode in photoelectrochemical measurements with Faradaic efficiency of ca. 1%. The construction as well as the stability of the system are also reported. The result shows that this biohybrid photocathode is capable of photocatalytic proton reduction under mild conditions.
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| 7. |
- Tian, Lei, 1987-
(författare)
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Exploring Dye-Sensitized Mesoporous NiO Photocathodes : from Mechanism to Applications
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increasing attention has been paid on solar energy conversion since the abundant solar energy possesses the potential to solve the problems on energy crisis and climate change. Dye-sensitized mesoporous NiO film was developed as one of the attractive photocathodes to fabricate p-type dye-sensitized solar cells (p-DSCs) and dye-sensitized photoelectrosynthetic cells (p-DSPECs) for electricity and chemical fuels generation, respectively. In this thesis, we designed a well-structured NiO-dye-TiO2 configuration by an atomic layer deposition (ALD) technique, with an organic dye PB6 as the photosensitizer. From kinetic studies of charge separation, ultrafast hole injection (< 200 fs) was observed from the excited state of PB6 dye into the valence band of NiO; dye regeneration (electron injection) was in t1/2 ≤ 500 fs, which is the fastest reported in any DSCs. On the basis of NiO-dye-TiO2 configuration, we successfully fabricated solid-state p-type DSCs (p-ssDSCs). Insertion of an Al2O3 layer was adopted to reduce charge recombination, i.e. NiO-dye-Al2O3-TiO2. Theoretically, such a configuration is possible to maintain efficient charge separation and depressed charge recombination. Based on NiO-dye-Al2O3-TiO2 configuration, the open-circuit voltage was improved to 0.48 V. Replacing electron conductor TiO2 with ZnO, short-circuit current density was increased to 680 μA·cm-2. The photocatalytic current density for H2 evolution was improve to 100 μA·cm-2 with a near unity of Faraday efficiency in p-DSPECs.However, to further improve the performance of p-DSCs is very challenging. In p-ssDSCs, the limitation was confirmed from the poor electronically connection of the electron conductor (TiO2 or ZnO) inside the NiO-dye films. We further investigated the electronic property of surface states on mesoporous NiO film. We found that the surface sates, not the bulk, on NiO determined the conductivity of the mesoporous NiO films. The dye regeneration in liquid p-DSCs with I-/I3- as redox couples was significantly affected by surface states. A more complete mechanism is suggested to understand a particular hole transport behavior reported in p-DSCs, where hole transport time is independent on light intensity. The independence of charge transport is ascribed to the percolation effect in the hole hopping on the surface states.
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| 8. |
- Tian, Lei, et al.
(författare)
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Mechanistic Insights into Solid-State p-Type Dye-Sensitized Solar Cells
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:43, s. 26151-26160
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Tidskriftsartikel (refereegranskat)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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| 9. |
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| 10. |
- Tian, Lei, et al.
(författare)
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Solid state p-type dye sensitized NiO-dye-TiO2 core-shell solar cells
- 2018
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 54:30, s. 3739-3742
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Tidskriftsartikel (refereegranskat)abstract
- Solid state p-type dye sensitized NiO-dye-TiO2 core-shell solar cells with an organic dye PB6 were successfully fabricated for the first time. With Al2O3 as an inner barrier layer, the recombination process between injected holes in NiO and injected electrons in TiO2 was significantly suppressed and the charge transport time was also improved.
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