He Lili,Han Xiao,Ge Chunhua,Zhang Rui,Hou Yufang,Zhang Xiangdong
Hydrothermal carbon microsphere (HTC) is a carbon-based fluorescent material, which can be synthesized by hydrothermal carbonization of glucose. In this article, a series of 4ZnO·B 2 O 3 ·H 2 O:Ln 3+ /HTC (where Ln = Eu or Tb) composites were prepared under hydrothermal conditions. The effects of the glucose concentration on the morphology, photoluminescence (PL) intensity and emission color of Zn 3.64 :Eu 0.24 [B 2 O 7 ]·H 2 O/HTCx and Zn 3.55 :Tb 0.3 [B 2 O 7 ]·H 2 O/HTC y were investigated. The relationship between morphology and PL intensity of composites was discussed. The results revealed that the presence of HTC did not change the original emission color of 4ZnO·B 2 O 3 ·H 2 O:Ln 3+ (where Ln = Eu or Tb) materials, but greatly increased their PL intensity, the sphere-like morphology composites have the strongest PL intensity. The Zn 3.64 :Eu 0.24 [B 2 O 7 ]·H 2 O/HTCx and Zn 3.55 :Tb 0.3 [B 2 O 7 ]·H 2 O/HTC y emit bright red light and green light, respectively, under respective excitation wavelengths. The present research suggests that the 4ZnO·B 2 O 3 ·H 2 O:Ln 3+ /HTC (where Ln = Eu or Tb) composites may be candidates of red and green phosphors for display and lighting applications.
The practical application of conventional Ti/SnO 2 -Sb electrodes is hindered by their low oxygen evolution potential (OEP) and rapid deactivation. Rare earth doping has been proposed to enhance electrode stability and catalytic activity; however, the comparative effects of different rare earth elements (e.g., La vs. Eu) on both structural and electrochemical properties remain unclear. In this paper, the fabrication of lanthanum- and europium-doped Ti/SnO 2 -Sb (TSS) electrodes and the electrochemical degradation of methylene blue (MB) were investigated. Although both lanthanum (La) and europium (Eu) are rare earth elements with many similarities, lanthanum (La)-modified electrode exhibits distinct performance characteristics. It is indicated that the Ti/SnO 2 -Sb-La (TSSL) electrode has a comparatively better crystal phase, enhanced surface hydrophobicity, and better electrochemical performance. The TSSL electrode exhibits a higher OEP of 1.84 V than other electrodes, showing a 0.15 V increase when compared with the undoped electrode. The peak oxidation current reaches 0.82 mA/cm 2 , which provides more active sites for the catalytic reaction. It is found that the La-doped electrode has better performance in wastewater treatment; the TSSL electrode shows a 45% increase in degradation efficiency when compared with the Ti/SnO 2 -Sb-Eu (TSSE) electrode for treatment of 50 ppm MB in 25 min. Moreover, the effects of current density and the initial concentration of MB were also investigated. Considering the degradation rate and energy consumption, the optimum current density for wastewater treatment is 20 mA/cm 2 . The outcome indicated that the degradation of MB was up to 98.5% in 25 min.
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