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81.
We prepared hyper-oxidized graphene (HOG) as a form of graphene derivative by additional oxidation of graphene oxide (GO) sheets. HOG, which formed more functional groups and isolated conjugated clusters on the sheets, accordingly showed high solubility in water and alcohols, high transmittance and film transparence, longer fluorescence decay constant time, and enhanced fluorescence in states of solution and solid. By contrast, GO has much weaker fluorescence in solution and its fluorescence is totally quenched in solid. The influences of concentration, metallic ions, and pH on HOG fluorescence in aqueous solution were also investigated in detail. Due to HOG’s strong fluorescence, direct visualization was realized on substrates and in solution. In addition, direct 3D fluorescence visualizations of HOG phase in polymer composites were achieved. These results show the great potential of HOG in a broad range of applications, from biological labeling, probes, and drug carriers to high-performance composites and nanomanipulation. 相似文献
82.
Dr. Nuo‐Wei Zhang Prof. Chuan‐Jing Huang Xiao‐Quan Zhu Jing‐Dong Xu Prof. Wei‐Zheng Weng Prof. Hui‐Lin Wan 《化学:亚洲杂志》2012,7(8):1895-1901
The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ‐Al2O3 catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N2 adsorption, X‐ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature‐programmed reduction (H2‐TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction. On the other hand, the effect of calcination temperature was less significant. Although the initial activity was increased by an increased calcination temperature, the catalyst without the feedstock pretreatment suffered a rapid deactivation. The reaction‐atmosphere pretreatment was revealed as a process that mainly modified the surface structure of the catalyst. In that process, the formation of a CoAl2O4‐like compound led to high Co metal dispersion after reduction, and the transformation of the carrier into α‐Al2O3 occurred over the catalyst surface. Both the high dispersion of cobalt and the presence of α‐Al2O3 surface phase were assumed as the important factors resulting in an excellent catalytic performance in terms of high activity and high stability. 相似文献
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Yan-Ning Liu Xiao-Long Weng Peng Zhang Wen-Xin Li Yu Gong Li Zhang Tian-Cheng Han Pei-Heng Zhou Long-Jiang Deng 《中国物理快报》2021,(3):44-49
Infrared metamaterial absorber(MMA) based on metal-insulator-metal(MIM) configuration with flexible design,perfect and selective absorption,has attracted much attention recently for passive radiative cooling applications.To cool objects passively,broadband infrared absorption(i.e.8-14 μm) is desirable to emit thermal energy through atmosphere window.We present a novel MMA composed of multilayer MIM resonators periodically arranged on a PbTe/MgF_2 bilayer substrate.Verified by the rigorous coup led-wave analysis method,the proposed MMA shows a relative bandwidth of about 45%(from 8.3 to 13.1 μm with the absorption intensity over 0.8).The broadband absorption performs stably over a wide incident angle range(below 50°) and predicts 12 K cooling below ambient temperature at nighttime.Compared with the previous passive radiative coolers,our design gets rid of the continuous metal substrate and provides an almost ideal transparency window(close to 100%)for millimeter waves over 1 mm.The structure is expected to have potential applications in thermal control of integrated devices,where millimeter wave signal compatibility is also required. 相似文献
87.
Xiaoting Li Tao Hu Biao Wang Wenjian Weng Gaorong Han Chenglu Song Ning Ma Piyi Du 《Journal of Physics and Chemistry of Solids》2013
(100) Oriented (PbxSr1−x)TiO3 (PST) thin films were prepared on indium tin oxide coated glass substrates by sol–gel technique with rapid thermal processing. The dielectric permittivity and tunability of the thin films with different dispersion degrees of orientation were investigated in detail by characterizing the full width at half maximum of their (100) peak based on rocking curves at different annealing temperatures. Influence of orientation dispersion on dielectric properties was exhibited in the tunable dielectric thin films. It shows that the dielectric constant and hence the tunability of the sol–gel derived PST thin films are improved with the decrease in the dispersion degree of orientation of the perovskite phase other than the increase in the content of crystalline phase in the thin films. The dielectric constant (capacitance) and figure of merit of the oriented thin films are 3–6 times and 1 times higher than that of randomly oriented thin film respectively. 相似文献
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Reagen Ying‐Tai Su Li‐Ko Chiu Shan‐Wei Weng Ying‐Shiun Chou Raymond Chien‐Chao Tsiang 《Journal of Polymer Science.Polymer Physics》2012,50(4):280-288
White polymeric light‐emitting diode (WPLED) based on a single polymer, poly(3‐hexylthiophene‐alt‐9,9‐dioctylfluorene) (PTAF), has been successfully demonstrated. This conjugated alternating copolymer, PTAF, comprises 50 mol % of 3‐hexylthiophene which is an orange‐red color chromophore and 50 mol % 9,9‐dioctylfluorene which is a bluish‐green color chromophore. It was synthesized by Suzuki cross‐coupling reaction and has a molecular weight of 15,021 and polydispersity of 1.36. Nanocomposite consisting PTAF and graphene nanosheets enhances the optoelectronic properties and the device fabricated with a configuration of ITO/PEDOT:PSS/(PTAF + 1% graphene)/Ca/Al shows two‐color white electroluminescence with CIE 1931 coordinates of (0.28, 0.34). The white luminescence from a single polymer affords the WPLED device a simple structure and low fabrication cost. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献