Browsing by Author "Chang, Chin-Hao"

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A Ruthenium-Based Biomimetic Hydrogen Cluster for Efficient Photocatalytic Hydrogen Generation from Formic Acid
(2015-04-20)
Chang, Chin-Hao
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Chen, Mei-Hua
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Du, Wan-Shan
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Gliniak, Jacek
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Lin, Jia-Hoa
A ruthenium-based biomimetic hydrogen cluster, [Ru-2(CO)(6)(-SCH2CH2CH2S)] (1), has been synthesized and, in the presence of the P ligand tri(o-tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500h(-1) and turnover numbers (TONs) over 24700 were obtained with less than 50ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 degrees C.
BIOT 373-Artificial myoglobin system design for electron transfer mechanism study and BioSolar cell applications
(2006-09-10)
Chang, Chin-Hao
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Wu, Tung-Kung
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Diau, Eric Wei Guang
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Luo, Li-Yang
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生物科技學系
Enhanced hydrogen generation from formic acid by a biomimetic ruthenium complex with a covalently bonded phosphine ligand
(2017-04-13)
Chen, Mei-Hua
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Lin, Jia-Hoa
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Li, Chuen-Ru
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Gliniak, Jacek
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Chang, Chin-Hao
A series of [Ru-2(CO)(5)(mu-SCH2CH2CH2S)PXS] complexes (Ru-2-S-2-PXS, X = phosphine ligands, S = 1-8) have been synthesized and evaluated for their photocatalytic H-2 generation efficiencies from formic acid decomposition. The [Ru-2(CO)(5)(mu-SCH2CH2CH2S)P(o-C6H4CH3)(3)] (Ru-2-S-2-PX4) catalyst + P(CH3)(3) ligand exhibited a high turnover frequency of 15,840h(-1) and turnover number of 24,536. A mechanistic investigation of the Ru-2-S-2-PX4 + FA/TEA catalyzed photocatalytic H-2 generation reaction using ATR-IR, EI-MS, and NMR techniques suggested that when Ru2-S2-PX4 was photoirradiated, the P(o-C6H4CH3)(3) was dissociated from the complex to form a new species, [Ru-2(CO)(5)(mu-SCH2CH2CH2S)]* (I). The free P(o-C6H4CH3)(3) then attacks a second molecule of Ru-2-S-2-PX4 to form Ru-2-S-2-(PX4)(2) and release of free CO, which is then combined with species I to form Ru-2-S-2. Subsequent attachment of formate ion to species Ru-2-S-2-PX4, Ru-2-S-2, and Ru-2-S-2-(PX4)(2) to form [Ru-2(CO)(5)(mu-SCH(2)CH(2)CH(2)SA]-HC00(-) (II), Ru-2-S-2-HCOO- (II') and Ru-2-S-2-PX4-HCOO- (II"), respectively. Rearrangement of complex II (or II' or II") and evolution of CO2 generate a transient complex [Ru-2(CO)(5)(mu-SCH2CH2CH2S)H (III), which then undergoes a protonation process to yield complex [Ru-2(CO)(5)(mu-SCH2CH2CH2S)H-2] (IV). Release of H-2 and re-incorporation of the formate anion as well as evolution of CO2 regenerates the active complex III and the cycle begins again. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Fabrication and Photovoltaic Characterization of Bio-Sensitized Solar Cells Using Myoglobin-Based Sensitizers
(2009-03-01)
Chang, Chih-Wei
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Chang, Chin-Hao
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Lu, Hsueh-Pei
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Wu, Tung-Kung
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Diau, Eric Wei-Guang
Myoglobin (Mb), reconstituted zinc protoporphyrin-apornyoglobin (ZnMb), and eosin-modified ZnMb (EoZnMb) were used as photosensitizers to functionalize TiO(2) nanocrystalline films for biosensitized solar-cell (BSSC) applications. For the Mb-sensitized SC, the poor cell performance was due to a reduction Fe(III) -> Fe(II) that produces a photocurrent density of the device smaller than its unsensitized counterpart. The efficiencies of power conversion of both ZnMb and EoZnMb-sensitized SC were enhanced about ten times due to superior charge separation between TiO(2) and the protein, and due to smaller current leakage between TiO(2) and the electrolyte. The cell performances of the BSSC devices are discussed in terms of an equivalent-circuit model.
High-Rate Hydrogen Generation by Direct Sunlight Irradiation with a Triruthenium Complex
(2019-02-04)
Wu, Tung-Kung
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Chen, Yi-Ting
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Peng, Chun-Sheng
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Lin, Jia-Hoa
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Gliniak, Jacek
Herein we report a biomimetic triruthenium catalyst that, when under direct sunlight irradiation, facilitates high-rate H-2 production from formic acid (FA) dehydrogenation. The system consists of 2 mu mol of catalyst and 6 mu mol of tri-o-tolylphosphine in 1 mL of dimethylformamide (DMF) and 4 mL of FA/triethylamine (TEA; 5:2). With 0.4 mM catalyst loaded, a high turnover frequency of 1.15 X 10(6) h(-1) was detected when under direct sunlight irradiation. In an experiment with 0.2 mM catalyst loaded, more than 140 L of H-2 (280 L of H-2 + CO2) was produced, and a turnover number of approximately 2.78 X 10(6) was obtained within 5 h without decline in H-2 generation activity, making it suitable for high-rate H-2 production.
Photo-induced chemical reduction of NADP plus by reconstituted metalloporphyrin myoglobin: An artificial photosynthesis model for photosystem I
(2009-08-16)
Chang, Chin-Hao
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Wu, Tung-Kung
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生物科技學系
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Department of Biological Science and Technology
Photoactivation Studies of Zinc Porphyrin-Myoglobin System and Its Application for Light-Chemical Energy Conversion
(2011)
Chang, Chin-Hao
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Hu, Yi-Ting
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Lo, Chen-Fu
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Luo, Liyang
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Lin, Hung-Ming
An artificial zinc porphyrin-myoglobin- based photo-chemical energy conversion system, consisting of ZnPP-Mb or ZnPE1-Mb as a photosensitizer, NADP(+) as an electron acceptor, and triethanolamine as an electron donor, has been constructed to mimic photosystem I. The photoirradiated product is able to reduce a single-electron acceptor protein cytochrome c, but cannot catalyze the two-electron reduction of acetaldehyde by alcohol dehydrogenase, thus demonstrating a single electron transfer mechanism. Furthermore, the artificial system can bifunctionally promote oxidoredox reactions, depending on the presence or absence of a sacrificial electron donor, thus suggesting its potential application in electrochemical regeneration steps involved in chemical transformation and/or energy conversion.
Sulfur-Doped Graphene Oxide Quantum Dots as Photocatalysts for Hydrogen Generation in the Aqueous Phase
(2017-08-24)
Gliniak, Jacek
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Lin, Jia-Hoa
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Chen, Yi-Ting
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Li, Chuen-Ru
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Jokar, Efat
Sulfur-doped graphene oxide quantum dots (S-GOQDs) were synthesized and investigated for efficient photocatalytic hydrogen generation application. The UV/Vis, FTIR, and photoluminescence spectra of the synthesized S-GOQDs exhibit three absorption bands at 333, 395, and 524 nm, characteristic of C=S and C=S stretching vibration signals at 1075 and 690 cm(-1), and two excitation-wavelength-independent emission signals with maxima at 451 and 520 nm, respectively, confirming the successful doping of S atom into the GOQDs. Electronic structural analysis suggested that the S-GOQDs exhibit conduction band minimum (CBM) and valence band maximum (VBM) levels suitable for water splitting. Under direct sunlight irradiation, an initial rate of 18166 mu molh(-1) g(-1) in pure water and 30519 mu molh(-1) g(-1) in 80% ethanol aqueous solution were obtained. Therefore, metal-free and inexpensive S-GOQDs hold great potential in the development of sustainable and environmentally friendly photocatalysts for efficient hydrogen generation from water splitting.
Ultrafast relaxation of zinc protoporphyrin encapsulated within apomyoglobin in buffer solutions
(2007-07-05)
Luo, Liyang
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Chang, Chin-Hao
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Chen, Yue-Ching
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Wu, Tung-Kung
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Diau, Eric Wei-Guang
The relaxation dynamics of a zinc protoporphyrin (ZnPP) in THF, KPi buffer, and encapsulated within apomyoglobin (apoMb) was investigated in its excited state using femtosecond fluorescence up-conversion spectroscopy with S-2 excitation (lambda(ex) = 430 nm). The S-2 -> S-1 internal conversion of ZnPP is ultrafast (tau < 100 fs), and the hot S-1 ZnPP species are produced promptly after excitation. The relaxation dynamics of ZnPP in THF solution showed a dominant offset component (tau = 2.0 ns), but it disappeared completely when ZnPP formed aggregates in KPi buffer solution. When ZnPP was reconstituted into the heme pocket of apoMb to form a complex in KPi buffer solution, the fluorescence transients exhibited a biphasic decay feature with the signal approaching an asymptotic offset: at lambda(em) = 600 nm, the rapid component decayed in 710 fs and the slow one in 27 ps; at lambda(em) = 680 nm, the two time constants were 950 fs and 40 ps. We conclude that (1) the fast-decay component pertains to an efficient transfer of energy from the hot S-1 ZnPP species to apoMb through a dative bond between zinc and proximal histidine of the protein; (2) the slow-decay component arises from the water-induced vibrational relaxation of the hot S-1 ZnPP species; and (3) the offset component is due to S-1 -> T-1 intersystem crossing of the surviving cold S-1 ZnPP species. The transfer of energy through bonds might lead the dative bond to break, which explains our observation of the degradation of ZnPP-Mb samples in UV-vis and CD spectra upon protracted excitation.