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以左旋多巴胺(L-3,4-dihydroxyphenylalanine,DOPA)为稳定剂,采用日光辐射光还原法,合成了强荧光发射的银纳米簇(silver nanoclusters,Ag NCs)。透射电镜分析表明,所合成的Ag NCs表现亚纳米非晶态结构。Ag NCs在可见-近红外波长范围内(400~750 nm)有明显光吸收带,最大荧光激发和发射峰分别为550和630 nm,荧光量子产率为2.3%(相对于罗丹明B)。Ag NCs的荧光强度与合成时的日光辐射时间、DOPA浓度以及pH值等因素有关。进一步优化了合成Ag NCs的条件。基于荧光猝灭原理,所合成的DOPA功能化的Ag NCs能选择性地灵敏响应Fe3+。修饰在Ag NCs表面的配体DOPA能够选择性地结合Fe3+,导致Ag NCs显著聚集,伴随荧光猝灭。Ag NCs具有的较高量子产率和红荧光发射特性,有利于提高Fe3+的分析灵敏度。 相似文献
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首先以大麻杆为前驱体,利用化学活化法,在氮气保护下高温炭化制备多孔结构碳材料。利用扫描电镜、X射线粉末衍射、氮吸脱附实验等探究温度和碱碳比对碳材料结构和孔径分布的影响。结果表明:当温度一定时,随着碱碳比增大比表面积呈抛物线上升。在碱碳比一定的情况下,温度升高,比表面积明显增大,比表面积可达1622.10 m^2·g^-1。然后,利用光还原法,以大麻杆碳材料为载体,磷钨酸为光催化还原剂、稳定剂和包覆剂,异丙醇作供电子体,在紫外光的照射下一步合成多酸基@Pt大麻杆碳复合材料并考察其电化学性能。研究表明此复合材料电催化氧化甲醇得到峰电流密度为4.87 mA·cm^-2,表现出了较好的催化活性和稳定性。 相似文献
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以左旋多巴胺(L-3,4-dihydroxyphenylalanine,DOPA)为稳定剂,采用日光辐射光还原法,合成了强荧光发射的银纳米簇(silvernanoclusters,AgNCs)。透射电镜分析表明,所合成的AgNCs表现亚纳米非晶态结构。AgNCs在可见-近红外波长范围内(400~750nm)有明显光吸收带,最大荧光激发和发射峰分别为550和630nm,荧光量子产率为2.3%(相对于罗丹明B)。AgNCs的荧光强度与合成时的日光辐射时间、DOPA浓度以及pH值等因素有关。进一步优化了合成AgNCs的条件。基于荧光猝灭原理,所合成的DOPA功能化的AgNCs能选择性地灵敏响应Fe3+。修饰在AgNCs表面的配体DOPA能够选择性地结合Fe3+,导致AgNCs显著聚集,伴随荧光猝灭。AgNCs具有的较高量子产率和红荧光发射特性,有利于提高Fe3+的分析灵敏度。 相似文献
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Polyacrylamide (PAM)–metal (M = gold, palladium) nanocomposites with metal nanoparticles homogeneously dispersed in the polymer matrix have been prepared via a novel ultraviolet irradiation technique at room temperature, which is based on the simultaneous occurrence of photo-reduction formation of the colloidal metal particles and photo-polymerization of the acrylamide (AM) monomer. The UV–vis absorption spectra and TEM were employed to characterize the M-PAM nanocomposites by different irradiation times. The average sizes of the colloidal gold and palladium particles dispersed in the nanocomposites were calculated by XRD patterns and TEM images. The present method may be extended to prepare other metal–polymer hybrid nanocomposite materials. 相似文献
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The photo-induced reduction of flavin mononucleotide (FMN) in aqueous solutions is studied by absorption spectra measurement under aerobic and anaerobic conditions. Samples without exogenous reducing agent and with the exogenous reducing agents ethylene-diamine-tetraacetic acid (EDTA) and dithiothreitol (DTT) are investigated. Under anaerobic conditions the photo-induced reduction with and without reducing agents is irreversible. Under aerobic conditions the photo-reduction without added reducing agent is small compared to the photo-degradation, and the photo-reduction of FMN by the reducing agents is reversible (re-oxidation in the dark). During photo-excitation of FMN the dissolved oxygen is consumed by singlet oxygen formation and subsequent chemical reaction. After light switch-off slow re-oxidation (slow absorption recovery) occurs due to air in-diffusion from surface. EDTA degradation by FMN excitation leads to oxygen scavenging. The quantum efficiencies of photo-reduction under aerobic and anaerobic conditions are determined. The re-oxidation of reduced FMN under aerobic conditions and due to air injection is investigated. 相似文献
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Coating films containing Au, Ag, Pt and Pd metal colloids have been prepared by sol-gel processing. It is shown that for oxide films the temperature where the metal particles are precipitated by heating in air depends on metal species: 200°C for Au, 600°C for Ag, 800°C for Pt and 1000°C for Pd. The use of reducing atmosphere lowers the temperature for formation of noble metal colloids. This procedure can be used for direct formation of metal colloids from metal ions in the film as well as reduction of oxide particles to metal particles in the film. For an organic-inorganic matrix, noble metal colloids are precipitated by thermal reduction or photo-reduction. Thermal reduction occurs as a result of reduction by decomposing organic matter. Photo-reduction occurs as a result of UV irradiation. 相似文献
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