Research on the Spectral Analysis and Stability of Ultraviolet-Enhanced Thin Films with Stable and Tunable Graphene Oxide-Rare Earth Complexes
LI Zhi-yuan1, LIU Xue-lian1,2, ZHENG An-dong1, WANG Guo-dong1, XIA Guo1,3, LU Hong-bo1,2*
1. National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009, China
2. Key Laboratory of Advanced Functional Materials and Devices, Anhui Province, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China
3. Key Laboratory of Optical Calibration and Characterization, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Abstract：As a new two-dimensional sheet material, graphene oxide sheets (GOSs) offers many advantages, such as high specific surface area, abundant surface oxygen-containing functional groups and good photothermal stability. In particular, rare earth complexes formed with GOSs exhibit excellent fluorescent characteristics from the combination of the inorganic rare earth element and the organic ligand. In order to combine the physicochemical properties of the two types of materials for applications in the field of ultraviolet (UV) spectroscopy, GOSs was compounded with rare earth complexes through means of hydrogen bond self-assembly, with appropriate organic ligands, namely phenanthroline (phen) and 2’2-bipyrimidine (bpm), being used as bridging molecules. This method was used to prepare the highly stable and tunable GOSs-rare earth complex fluorescent materials GOSs-Eu(BA)3phen and GOSs-Eu(TTA)3bpm. A corresponding poly vinyl alcohol (PVA) mixed UV enhanced film was also prepared for each GOSs-rare earth complex, respectively. The properties of the materials were studied using infrared (IR) spectroscopy, scanning electron microscopy (SEM), and metallographic microscopy. The films were also characterized by their absorption and fluorescence spectra. In addition, the thermal stability of the UV-enhanced materials was tested using thermogravimetric analysis (TGA), and the photostability of the UV-enhanced film before and after reacting with the hydrogen bonds of the GOSs was tested using fluorescence intensity experiments. IR spectroscopy results showed that the characteristic absorption peaks of the organic ligands shifted after the complex formation, indicating that there is significant coordination between Eu3+ and the ligands in the rare earth complex. In addition, the characteristic chemical shift peaks of the bridging ligands also shifted, showing that the GOSs and the rare earth complexes were combined through hydrogen bonding of the bridging molecules. The absorption and fluorescence spectra results indicated that the absorption peak of the enhanced film was in the range of 200～400 nm, and that the main fluorescence peak was at about 612 nm, which is the characteristic red fluorescent peak of Eu3+. Different ligands achieved different absorption ranges, thus leading to differences in fluorescence behavior. The pictures from SEM and metallographic microscopy clearly showed that the rare earth complex particles adhered to the graphene sheet after the compositing process. The photostability test further showed that, following the compositing process, the photobleaching degree of Eu(BA)3phen and Eu(TAA)3bpm rare earth complex fluorescent materials decreased by 4.26% and 6.41% respectively, after 25 fluorescence intensity tests. The TGA results showed that the thermal stability of the rare earth complexes was greatly improved after the formation of hydrogen bonds with GOSs. In summary, the prepared UV-enhanced materials were shown to exhibit excellent fluorescent characteristics and stability, and will have broad applications in UV detection, especially in the field of narrow-band differential detection.
李志远，刘雪连，郑安东，王国栋，夏 果，陆红波. GOSs-稀土配合物紫外增强材料的光谱分析与稳定性研究[J]. 光谱学与光谱分析, 2020, 40(02): 379-384.
LI Zhi-yuan, LIU Xue-lian, ZHENG An-dong, WANG Guo-dong, XIA Guo, LU Hong-bo. Research on the Spectral Analysis and Stability of Ultraviolet-Enhanced Thin Films with Stable and Tunable Graphene Oxide-Rare Earth Complexes. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(02): 379-384.
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