共查询到20条相似文献,搜索用时 31 毫秒
1.
Yao-Hsuan Tseng Der-Shan Sun Wen-Shiang Wu Hao Chan Ming-Syuan Syue Han-Chen Ho Hsin-Hou Chang 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2–Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized.Methods
Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet–visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated.Results
The apparent quantum efficiency for visible light illuminated TiO2–Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2–Pt successfully ameliorated the subcutaneous infection in mice.Conclusions
This is the first demonstration of in vivo antibacterial use of TiO2–Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2–Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo.General significance
These findings suggest that the TiO2–Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings. 相似文献2.
Mona Saif 《Inorganica chimica acta》2007,360(9):2863-2874
Mesoporous Ln(III)-TiO2 (Ln = Tb, Eu, Sm) nanomaterials composites have been successfully synthesized by using sol-gel technique.XRD pattern, FT-IR, Raman spectra, and SEM were used to characterize the Ln(III)-TiO2 nanomaterials. The prepared lanthanide doped TiO2 nanomaterials have anatase phase and exhibit Ti-O-Ln bond. The absorption spectra of all prepared samples reflect the increasing photoresponse of doped samples to visible light over pure TiO2. Surface area is remarkably increased due to lanthanide ion-doping.Two newly prepared Ln(III)-TiO2 (Ln = Eu, Sm) luminescent nanomaterials exhibit enhanced pure red or orange light emission due to energy transfer from host TiO2 to guest Eu(III) or Sm(III), respectively.In addition, the commercially available textile dye Remazol Red RB-133 degradation was used as a probe reaction to determine the efficiency of the Ln(III)-TiO2 photocatalysts. The Ln(III) doping brought about remarkable improvement in the photoactivity over pure TiO2. 相似文献
3.
Donna L. Jacob Joshua D. Borchardt Leelaruban Navaratnam Marinus L. Otte Achintya N. Bezbaruah 《International journal of phytoremediation》2013,15(2):142-153
Bioavailability of engineered metal nanoparticles affects uptake in plants, impacts on ecosystems, and phytoremediation. We studied uptake and translocation of Ti in plants when the main source of this metal was TiO2 nanoparticles. Two crops (Phaseolus vulgaris (bean) and Triticum aestivum (wheat)), a wetland species (Rumex crispus, curly dock), and the floating aquatic plant (Elodea canadensis, Canadian waterweed), were grown in nutrient solutions with TiO2 nanoparticles (0, 6, 18 mmol Ti L?1 for P. vulgaris, T. aestivum, and R. crispus; and 0 and 12 mmol Ti L?1 for E. canadensis). Also examined in E. canadensis was the influence of TiO2 nanoparticles upon the uptake of Fe, Mn, and Mg, and the influence of P on Ti uptake. For the rooted plants, exposure to TiO2 nanoparticles did not affect biomass production, but significantly increased root Ti sorption and uptake. R. crispus showed translocation of Ti into the shoots. E. canadensis also showed significant uptake of Ti, P in the nutrient solution significantly decreased Ti uptake, and the uptake patterns of Mn and Mg were altered. Ti from nano-Ti was bioavailable to plants, thus showing the potential for cycling in ecosystems and for phytoremediation, particularly where water is the main carrier. 相似文献
4.
Yang F Liu C Gao F Su M Wu X Zheng L Hong F Yang P 《Biological trace element research》2007,119(1):77-88
The improvement of spinach growth is proved to relate to N2 fixation by nano-anatase TiO2 in this study. The results show that all spinach leaves kept green by nano-anatase TiO2 treatment and all old leaves of control turned yellow white under culture with N-deficient solution. And the fresh weight,
dry weight, and contents of total nitrogen, , chlorophyll, and protein of spinach by nano-anatase TiO2 treatment presented obvious enhancement compared with control. Whereas the improvements of yield of spinach were not as good
as nano-anatase TiO2 treatment under N-deficient condition, confirming that nano-anatase TiO2 on exposure to sunlight could chemisorb N2 directly or reduce N2 to NH3 in the spinach leaves, transforming into organic nitrogen and improving the growth of spinach. Bulk TiO2 effect, however, was not as significant as nano-anatase TiO2. A possible metabolism of the function of nano-anatase TiO2 reducing N2 to NH3 was discussed. 相似文献
5.
Chia-Liang Cheng Der-Shan Sun Wen-Chen Chu Yao-Hsuan Tseng Han-Chen Ho Jia-Bin Wang Pei-Hua Chung Jiann-Hwa Chen Pei-Jane Tsai Nien-Tsung Lin Mei-Shiuan Yu Hsin-Hou Chang 《Journal of biomedical science》2009,16(1):7
Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2. 相似文献
6.
Background Purpose
Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading.Methods
Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV–vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations.Results
DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV–vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2.Conclusion
Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV–vis light. 相似文献7.
Glucose biosensor based on the room-temperature phosphorescence of TiO2/SiO2 nanocomposite 总被引:1,自引:0,他引:1
The direct immobilization of glucose oxidase (GOD) on TiO2/SiO2 nanocomposite and its application as glucose biosensor were investigated. The room-temperature phosphorescence of TiO2/SiO2 nanocomposite can be quenched by hydrogen peroxide (H2O2). The detection of glucose may be accomplished by monitoring the formation of hydrogen peroxide which generated in the oxidation process of glucose with the catalysis of GOD. To our surprise, by using a 96-hole polyporous plate accessory of fluorescence spectrophotometer, the biosensor exhibits excellent linear response to glucose concentrations ranging from 1.0 × 10−9 to 1.0 × 10−2 M with a detection limit of 1.2 × 10−10 M. The TiO2/SiO2 nanocomposite can be used as both supporting material and signal transducer. The phosphorescence intensity and color of the biosensor change obviously and even could be observed with naked eyes by continuous addition of glucose. Based on the room-temperature phosphorescence of TiO2/SiO2 nanocomposite, a new method of solid substrate-room-temperature phosphorimetry (SS-RTP) for glucose determination is proposed. A glucose biosensor was fabricated with wide determination concentration range, low detection limit, high sensitivity, and fast response time. And the biosensor has been successfully applied to the determination of glucose in human blood serum. The coacervation of GOD enzyme and its interaction with TiO2/SiO2 nanocomposite enlarge the surface area and enhance the chemical stability of GOD. The nice biocompatibility, large surface area, good chemical stability and nontoxicity of the TiO2/SiO2 nanocomposite have made this material suitable for functioning as biosensor. 相似文献
8.
Mifen Cui Shuai Pan Zhe Tang Xian Chen Xu Qiao 《Chemical Speciation and Bioavailability》2017,29(1):60-69
The composite TiO2/Mo-TiO2 were prepared by a modified sol-gel method. The prepared catalysts were characterized by X-ray diffraction, BET analysis, SEM, X-ray photoelectron spectroscopy, and UV–vis diffused reflectance spectroscopy techniques. The structural characterization results demonstrated that Mo was successfully doped into the TiO2 lattice and caused slight changes in the physiochemical properties. The UV–vis DRS showed a red shift of the adsorption edge to the visible region. The photocatalytic decomposition efficiencies of the catalysts were examined with toluene as a typical VOC in a continuous flow reactor. The photocatalytic activity of the n-n heterogeneous TiO2/Mo-TiO2 was greater than that of pure TiO2 and Mo-TiO2, and the catalyst containing a Mo/Ti mole ratio of 2.5% exhibited optimum photocatalytic properties. In general, a relative humidity of 35%, a higher oxygen content, a lower initial toluene concentration, and a higher UV intensity were beneficial for toluene decomposition. 相似文献
9.
Hanieh Mohajjel Shoja Laleh Ahmadi Maryam Kolahi Elham Mohajel Kazemi 《Physiology and Molecular Biology of Plants》2021,27(9):2071
Rapid commercialization, industrialization and the use of nanotechnology has led to an increase in the distribution of nanoparticles (NPs) in the environment. The most common metal oxide NPs which is present within products is Titanium dioxide (TiO2). TiO2 NPs have photocatalytic nature and can affect plant growth. The current study investigated the morphological, anatomical and biochemical features of Baby sun rose (Aptenia cordifolia) after exposure to different concentrations of TiO2 nanoparticles (0, 1, 5, 10 and 20 mg L−1). Treatment with TiO2 NPs showed changes in the morphological features and increased photosynthetic pigmentation within the plant. An increase in the level of phenolics (12%) and flavonoid compounds (13%) was observed when plants were treated with moderate levels of TiO2 NPs. A reduction in the diameter of the vascular bundles and increased thickening of the transverse wall were observed in several samples. The number of scattered vascular bundles in the stems increased. The morphological, biochemical, and anatomical responses of Baby sun rose indicates that plants can adapt to environments contaminated with up to 20 mg L−1 TiO2 NPs. The cultivation of Baby sun rose plants in environments polluted with TiO2 NPs is recommended. This study enhances the knowledge of the effect of TiO2 NPs on the growth of Baby sun rose which is an ornamental plant, widely cultivated in different regions of Iran. The results of this study suggest that contaminated environments up to 20 mg L−1 TiO2 NPs can be managed by phytoremediation. Further studies are needed to investigate this plant''s tolerance strategies against stress caused by TiO2 NPs and bulk TiO2 as well as the effect of other nanoparticles on plant. 相似文献
10.
Was improvement of spinach growth by nano-TiO2 treatment related to the changes of Rubisco activase? 总被引:1,自引:0,他引:1
Fengqing Gao Chao Liu Chunxiang Qu Lei Zheng Fan Yang Mingyu Su Fashui Hong 《Biometals》2008,21(2):211-217
Characterized by a photo—catalysis property, nano-anatase TiO2 is closely related to photosynthesis of spinach. It could not only improve light absorbance, transformation from light energy
to electron energy and active chemical energy, but also promote the activity of Rubiso activase of spinach. However, the relation
between the activity of Rubiso activase and the growth of spinach promoted by nano-anatase TiO2 treatment remains largely unclear. In this study, we find that the amount and the activity of Rubiso activase are obviously
increased by nano-anatase TiO2 treatment, which led to the great promotion of Rubsico carboxylation and the high rate of photosynthesis, thus improving of
spinach growth. The significant enhancement of Rubiso activase activity of nano-anatase TiO2 treated spinach is also accompanied by conformational changes as determined by spectroscopic analysis. But bulk TiO2 effect is not as significant as nano-anatase TiO2, as the grain size of nano-anatase TiO2 (5 nm) is much smaller than that of bulk TiO2, which entered spinach cell more easily. 相似文献
11.
Yanmei Duan Huiting Liu Jinfang Zhao Chao Liu Zhongrui Li Jinying Yan Linglan Ma Jie Liu Yaning Xie Jie Ruan Fashui Hong 《Biological trace element research》2009,130(2):162-171
Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO2 was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which TiO2 exerts its toxicity has not been completely understood. In this report, we investigated the mechanisms of nano-anatase TiO2 (5 nm) on LDH activity in vitro. Our results showed that LDH activity was greatly increased by low concentration of nano-anatase TiO2, while it was decreased by high concentration of nano-anatase TiO2. The spectroscopic assays revealed that the nano-anatase TiO2 particles were directly bound to LDH with mole ratio of [nano-anatase TiO2] to [LDH] was 0.12, indicating that each Ti atom was coordinated with five oxygen/nitrogen atoms and a sulfur atoms of amino acid residues with the Ti–O(N) and Ti–S bond lengths of 1.79 and 2.41 Å. We postulated that the bound nano-anatase TiO2 altered the secondary structure of LDH, created a new metal ion-active site for LDH, and thereby enhanced LDH activity. 相似文献
12.
Background
Titania dioxide (TiO2) photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved.Methodology/Principal Findings
Using thermal reduction method, here we synthesized silver-nanostructures coated TiO2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO2, carbon-doped TiO2 [TiO2 (C)] and nitrogen-doped TiO2 [TiO2 (N)], TiO2 (N) showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO2 (N) substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials.Conclusion/Significance
Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property. 相似文献13.
近年来,二氧化钛纳米颗粒(TiO2NPs)环境释放量不断增加,并通过多种途径进入湿地生态系统,不可避免地影响到湿地生态系统环境和功能。然而,关于TiO2NPs对沼泽土壤反硝化作用和氧化亚氮(N2O)排放的影响机及制尚不明确。选择典型沼泽土壤,通过室内培养实验研究土壤理化性质、反硝化酶活性、反硝化速率(DNR)和N2O排放对不同剂量TiO2NPs 0 mg/kg (CK)、10 mg/kg (A10)、100 mg/kg (A100)、1000 mg/kg (A1000)输入的响应,探讨TiO2NPs输入对沼泽土壤反硝化作用和N2O排放影响的内在机制。结果表明:不同剂量TiO2NPs处理显著降低了土壤pH (P<0.05),A10处理显著降低土壤总有机碳(TOC)含量(P<0.01),A1000处理显著降低硝态氮(NO3--N)和亚硝态氮(NO2--N)含量(P<0.05)。TiO2NPs处理抑制硝酸盐还原酶(NAR)活性,促进一氧化氮还原酶(NOR)和氧化亚氮还原酶(NOS)活性(P<0.01),A1000处理先促进后抑制了亚硝酸盐还原酶(NIR)活性(P<0.05)。不同剂量TiO2NPs处理抑制了土壤DNR,促进了N2O排放,TiO2NPs处理通过抑制NIR活性,降低土壤DNR,同时通过促进NOR活性,提高N2O排放。综上,TiO2NPs输入通过影响反硝化还原酶活性改变沼泽土壤反硝化过程,导致沼泽土壤N2O排放增加,改变湿地氮的源、汇功能,影响全球气候变化。为TiO2NPs输入的湿地环境风险评估研究提供理论基础。 相似文献
14.
15.
Titanium dioxide (TiO2)reflects ultraviolet light, and so could beexpected to protect the occlusion bodies (OBs)of nucleopolyhedroviruses (NPVs) fromdegradation by sunlight. However, in thepresence of sunlight and water, TiO2catalyzes the formation of hydrogen peroxide,which can degrade OBs. We tested microfineTiO2 that had been photostabilized(particles were coated to prevent catalyticactivity), as a UV protectant for the OBs ofthe NPV of Helicoverpa zea (Boddie). Inthe absence of UV, activity of the OBs wasreduced by nonphotostabilized TiO2 but wasunaffected by photostabilized TiO2 or byzinc oxide (ZnO). None of these materialsinfluenced larval feeding rates. Undersimulated sunlight, photostabilizedTiO2 protected the OBs to a greater degreethan did ZnO. Photostabilized TiO2 wascompatible with a viral enhancer, thefluorescent brightener Blankophor HRS. Undersimulated sunlight, both materials increasedactivity of the OBs, relative to OBs withneither material, in a largely additive manner. In bioassays of foliage collected from fieldplots of lima bean plants sprayed with OBs withor without one or both of these materials,TiO2 increased persistence of the OBs, butBlankophor HRS had no significant effect. 相似文献
16.
Kimura Sonoko D. Schmidtke Knut Tajima Ryosuke Yoshida Koichi Nakashima Hiroshi Rauber Rolf 《Plant and Soil》2004,258(1):91-101
The adzuki bean (Vigna angularis (Wild.) Ohwi and Ohashi) and common bean (Phaseolus vulgaris L.) have a high physiological demand for N. A 2-year field study was conducted to investigate the seasonal change of available soil N and symbiotic N2 fixation usage. The beans were seeded at two densities, 22.2 plants m–2 with a row spacing of 0.3 m and 11.1 plants m–2 with a row spacing of 0.6 m. The amount of fixed N2 in the shoot was calculated using the 15N natural abundance method. The common bean demonstrated low N2 fixation and the ability to accumulate high levels of soil N. Soil nitrate under the common bean was continually absorbed. The adzuki bean, on the other hand, had a remarkable peak of N accumulation in the early reproductive stage. This was mainly due to N2 fixation, though the soil nitrate level was high. Narrowing the plant row spacing increased the dry matter yield of both species, but the origin of the increased N differed between the species. For the first 77 DAP in 1999 (73 DAP in 2000) the N increase for both beans was due to both soil and atmospheric N2. At harvest, though, the increase of N in common bean was mainly due to soil N, while that in adzuki bean was mainly due to atmospheric N2. It can be concluded that the low symbiotic N2 fixation ability of common bean was due to its high soil N uptake ability and constant N accumulation, which enabled an efficient soil N absorption. Adzuki bean absorbed N mainly for a short period and depended more on symbiotically fixed N2 and, in contrast to common bean, left a high level of NO3-N remaining in the soil after cropping. 相似文献
17.
Previous research showed that nano-TiO2 could significantly promote photosynthesis and greatly improve growth of spinach, but, we also speculated that an increase
of spinach growth by nano-TiO2 treatment might be closely related to the change of nitrogen metabolism. The effects of nano-anatase TiO2 on the nitrogen metabolism of growing spinach were studied by treating them with nano-anatase TiO2. The results showed that, nano-anatase TiO2 treatment could obviously increase the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and
glutamic-pyruvic transaminase during the growing stage. Nano-anatase TiO2 treatment could also promote spinach to absorb nitrate, accelerate, inorganic nitrogen (such as NO
3
t-
−N and NH
4
+
−N) to be translated into organic nitrogen (such as protein and chlorophyll), and enhance the fresh weight and dry weights. 相似文献
18.
Minerals such as titanium dioxide, TiO2, and zinc oxide, ZnO, are well known active semiconductor photocatalysts used extensively in heterogeneous photocatalysis to destroy environmental pollutants that are organic in nature. They are also extensively used in sunscreen lotions as active broadband sunscreens that screen both UVB (290-320 nm) and UVA (320-400 nm) sunlight radiation and as high SPF makers. When so photoactivated by UV light, however, these two particular metal oxides are known to generate highly oxidizing radicals (OH and ) and other reactive oxygen species (ROS) such as H2O2 and singlet oxygen, 1O2, which are known to be cytotoxic and/or genotoxic. Hydroxyl (OH) radicals photogenerated from photoactive TiO2 specimens extracted from commercial sunscreen lotions [R. Dunford, A. Salinaro, L. Cai, N. Serpone, S. Horikoshi, H. Hidaka, J. Knowland, FEBS Lett. 418 (1997) 87] induce damage to DNA plasmids in vitro and to whole human skin cells in cultures. Accordingly, the titanium dioxide particle surface was modified to produce TiO2 specimens of considerably reduced photoactivity. Deactivation of TiO2 diminishes considerably, in some cases completely suppresses damage caused to DNA plasmids, to human cells, and to yeast cells compared to non-modified specimens exposed to UVB/UVA simulated solar radiation. The photostabilities of sunscreen organic active agents in neat polar and apolar solvents and in actual commercial formulations have been examined [N. Serpone, A. Salinaro, A.V. Emeline, S. Horikoshi, H. Hidaka, J. Zhao, Photochem. Photobiol. Sci. 1 (2002) 970]. With rare exceptions, the active ingredients undergo photochemical changes (in some cases form free radicals) and the sunscreen lotions lose considerable Sun protection efficacy only after a relatively short time when exposed to simulated sunlight UVB/UVA radiation, confirming the recent findings by Sayre et al. [R.M. Sayre, J.C. Dowdy, A.J. Gerwig, W.J. Shields, R.V. Lloyd, Photochem. Photobiol. 81 (2005) 452]. 相似文献
19.
Su M Mingyu S Wu X Xiao W Liu C Chao L Qu C Chunxiang Q Liu X Xiaoqing L Chen L Liang C Huang H Hao H Hong F Fashui H 《Biological trace element research》2007,119(2):183-192
Being a proven photocatalyst, nano-anatase is capable of undergoing electron transfer reactions under light. In previous studies
we had proven that nano-anatase improved photosynthesis and greatly promoted spinach growth. The mechanisms by which nano-anatase
promotes energy transfer and the conversion efficiency of the process are still not clearly understood. In the present paper,
we report the results obtained with the photosystem II (PSII) isolated from spinach and treated by nano-anatase TiO2 and studied the effect of nano-anatase TiO2 on energy transfer in PSII by spectroscopy and on oxygen evolution. The results showed that nano-anatase TiO2 treatment at a suitable concentration could significantly change PSII microenvironment and increase absorbance for visible
light, improve energy transfer among amino acids within PSII protein complex, and accelerate energy transport from tyrosine
residue to chlorophyll a. The photochemical activity of PSII (fluorescence quantum yield) and its oxygen-evolving rate were enhanced by nano-anatase
TiO2. This is viewed as evidence that nano-anatase TiO2 can promote energy transfer and oxygen evolution in PSII of spinach. 相似文献
20.
P.V.V. Jayaweera 《Inorganica chimica acta》2008,361(3):707-711
In Gratzel’s cell, the electrons injected by the photo-excitation of dye molecules, anchored to a mesoporous TiO2 film, efficiently diffuse to the back contact achieving solar energy conversion at efficiencies exceeding 10%. The mesoporous TiO2 surface constituted of randomly arranged nanocrystallites with a roughness factor of the order 1000 is heavily populated with traps, defects and adsorbed species which act as recombination centers. Nevertheless, the cell functions, mitigating recombination expected to occur via the interaction electrons at the surface. Evidence based mainly on 1/f noise measurements is presented to show that dye bonded to the TiO2 surface passivates recombination centers. Furthermore the suppression of trapping-detrapping events at the surface increases the diffusion coefficient of the electrons through the nanocrystalline matrix facilitating electron transport to the back contact. The Gratzel cell is also unique, none of the high bandgap oxide materials other than TiO2 yield energy conversion and quantum efficiencies as high as that of the cells based on TiO2. 1/f noise measurements also reveal a distinct difference between TiO2 and ZnO mesoporous films suggesting that the films made from the latter material are more intensely populated with surface states that mediate recombination. 相似文献