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71.
The effects of adding dispersed powders of various forms of titanium(IV) dioxide on the photodegradation of polystyrene have been examined using FT-IR spectroscopy from the following points of view: effect of crystal form, concentration of pigment, transition metal ion, dopant concentration, calcination temperature of pigment, and pigment coating.The rate of photodegradation of polystyrene is reduced by adding certain grades of TiO2 such as coated TiO2 particles or TiO2 doped with small percentages of Cr or Mn ions. The rate is increased on adding TiO2 doped with V and especially Mo or W ions. The anatase form of TiO2 is more photoactive than the rutile form, as is the effect of increasing the calcination temperature of the pigment. The concentration dependences of the degradation rates are complex, but can be directly related to the percentage of anatase achieved after calcination. Even the most aggressive of the metal-doped pigments are less photoactive than a Degussa P25 material, containing rutile and anatase. 相似文献
72.
Douglas Gouvêa Gilberto J. PereiraLéon Gengembre Marlu C. SteilPascal Roussel Annick RubbensPilar Hidalgo Ricardo H.R. Castro 《Applied Surface Science》2011,257(9):4219-4226
In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO2 nanoparticles plays an important role in the system's energetics and stability. Using X-ray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO2 with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO2 nanoparticles stability. 相似文献
73.
Tiago Pinheiro Braga Ant?nio Narcísio Pinheiro Edson R. Leite Regina Cláudia R. dos Santos Antoninho Valentini 《催化学报》2015,(5)
Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an u... 相似文献
74.
钙钛矿太阳能电池(PSCs)因易于制备、生产成本低和能量转换效率高而受到广泛关注。聚乙撑二氧噻吩-聚(苯乙烯磺酸盐)(PEDOT∶PSS)由于具有易低温加工、透光度高和适宜空穴迁移率等特点而成为PSCs中空穴传输层的研究热点。本文简述了倒置PSCs的结构及工作原理,重点介绍了掺杂PEDOT∶PSS空穴传输层在PSCs领域的研究现状。分别从有机化合物掺杂剂、无机化合物掺杂剂和表面活性剂掺杂剂三个类别概述了掺杂PEDOT∶PSS空穴传输层对PSCs性能的影响。最后,对该领域存在的问题提出潜在措施以改善PEDOT∶PSS掺杂层在PSCs中的应用。 相似文献
75.
76.
Polyaniline (PANI) microspheres were prepared by electrochemical polymerization. To obtain PANI having novel micro- and nanostructures,
by the potential scan technique, aniline was electropolymerized in the presence of DNA using four polymerizing solutions containing
different acids: H2SO4, C6H5SO3H, HClO4, and CF3COOH. The growth rate of the PANI film on the electrode surface decreased by the presence of DNA, suggesting that DNA interacted
with the growing PANI molecules during the electropolymerization. The growth rate also depended on the type of acid, i.e.,
the anion, in the polymerizing solution and was in the order of SO4
2− > C6H5SO3
− > ClO4
− > CF3COO−, which significantly coincided with the reverse order of the Hofmeister series representing the lyophilicity of the anion.
When aniline was electropolymerized in the CF3COOH polymerizing solution containing DNA, PANI microspheres were obtained without any templates. This PANI showed a sufficient
redox activity in the less acidic solution in which the ordinary PANI has a slight redox activity. On the other hand, the
electronic state of the PANI differed from the ordinary ones; a new absorption band was evident at 620 nm. The difference
in the redox activity and electronic state suggested that the DNA molecules were incorporated in the PANI and electronically
interacted with the PANI molecules. 相似文献
77.
MesomorphicCharacteristicsofInducedChiralNematicPhaseof[SmecticLCP,PS(4BC/DM)/NematicLC,E7/ChiralDopant,CB┐15]┐TernaryComposi... 相似文献
78.
A. T. Davidson A. G. Kozakiewicz T. E. Derry J. D. Comins M. Suszynska 《辐射效应与固体损伤》2013,168(6-12):629-636
Pure and europium doped NaCl and KCl crystals have been irradiated with 60 Co gamma rays and with ultraviolet light. The dose was 10 v kGy and temperatures during irradiation were ambient and liquid nitrogen. The effects of irradiation are determined using optical absorption and thermoluminescence. The role of the europium dopant is compared for the two materials. Factors investigated include the temperature of irradiation, the concentration of the dopant and the state of impurity aggregation and precipitation. A link is indicated between impurity precipitates and UV stimulated thermoluminescence. 相似文献
79.
A series of novel hyperbranched polymers(HBPs) consisting of a 2,7-subsituted 9-(heptadecan-9-yl)-9H-carbazole unit(A_2+A_2') and a tetra-substituted green thermally activated delayed fluorescence(TADF) dye of 2,3,5,6-tetra(9Hcarbazol-9-yl)-4-pyridinecarbonitrile(4CzCNPy, B4) have been synthesized via Suzuki cross-coupling reaction following an "A2+A2'+B_4" method. The polymers are named according to the polymerization ratio of 4CzCNPy monomer(5 mol%, 10 mol% and 15 mol% for HBPs of P2-P4 respectively, and 0 mol% for the control linear polymer P1). Their thermal, optoelectronic and electrochemical properties have been characterized by a combination of techniques. All the polymers exhibit high thermal stability with the decomposition temperatures(Td) above 400 ℃ and glass transition temperatures(Tg) up to 98 ℃. Unfortunately, the incorporation of TADF moiety into these HBP materials induced non-TADF characteristics. However, when the HBPs functionalized as the host for our previously developed 4CzCNPy TADF dopant in solution processed devices, maximum external quantum efficiency of 5.7% and current efficiency of 17.9 cd/A have been achieved in P3-based device, which is significantly higher than those of 1.5% and 4.2 cd/A for the linear polymer P1. 相似文献
80.
Tiago Pinheiro Braga Ant?nio Narcísio Pinheiro Edson R.Leite Regina Cláudia R.dos Santos Antoninho Valentini 《催化学报》2015,(5):712-720
Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity. 相似文献