This paper reports a novel strategy for preparing redox-active electrolyte through introducing a redox-mediator(p-phenylenediamine,PPD) into KOH electrolyte for the application of ball-milled MnO 2-based supercapacitors.The morphology and compositions of ball-milled MnO 2 were characterized using scanning electron microscopy(SEM) and X-ray diffraction(XRD).The electrochemical properties of the supercapacitor were evaluated by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD),and electrochemical impedance spectroscopy(EIS) techniques.The introduction of p-phenylenediamine significantly improves the performance of the supercapacitor.The electrode specific capacitance of the supercapacitor is 325.24 F g-1,increased by 6.25 folds compared with that of the unmodified system(44.87 F g-1) at the same current density,and the energy density has nearly a 10-fold increase,reaching 10.12 Wh Kg-1.In addition,the supercapacitor exhibits good cycle-life stability.
The flower-like microsphere Bi2WO6 with an average diameter of 2.5 μm is synthesized by a simple hydrothermal method in the presence of surfactant sodium dodecyl sulfate （SDS） or polyvinylpyrrolidone （PVP）. The crystalline phase, compositions, morphology, microstructure, surface area and band gap energy of the Bi2WO6 are characterized by X-ray diffraction, X-ray energy-dispersive spectrum, scanning electron microscopy, transmission electron microscopy and absorption spectra. It is found that surfactant has a significant influence on the microstructure and properties of the samples. The surfaetant SDS en- hances the surface area and photocatalytic activity of Bi2WO6, while the surfactant PVP has an opposite effect. Under Xe lamp irradiation, the Bi2WO6 sample prepared in the presence of SDS can degrade dye Rhodamine B （RhB） effectively.
HUANG Yi,WU JiHuai,HUANG MiaoLiang,LIN JianMing & HUANG YunFang Engineering Research Center of Environment-Friendly Functional Materials,Ministry of Education
An upconversion luminescence powder TiO2:(Er3+,Yb3+) is prepared by a hydrothermal method and used to fabricate dye-sensitized solar cell (DSSC).The TiO2:(Er3+,Yb3+) powder undergoes upconversion luminescence,converting infrared light which the dye can not absorb into visible light with wavelengths of 510-700 nm which the dye can absorb,increasing the photocurrent of the DSSC.TiO2:(Er3+,Yb3+) also acts as a p-type dopant,heightening the Fermi level of the oxide film,which increases the photovoltage of the DSSC.The best performance of the DSSC is found when the ratio of TiO2/luminescence powder is 1/3 in the luminescence layer.Under simulated solar irradiation of 100 mW cm-2 (AM 1.5),the DSSC containing TiO2:(Er3+,Yb3+) doping achieves a light-to-electricity energy conversion efficiency of 7.28% compared with 6.41% for the undoped DSSC.
Gd_2O_3 :Eu^(3+) downconversion luminescent powder was prepared using the homogeneous precipitation method. Its optical properties were analyzed and it was introduced into a dye-sensitized solar cell (DSSC). As a luminescence medium, Gd_2O_3 :Eu^(3+) improved light harvesting via conversion luminescence and increased the photocurrent of the DSSC. As a p-type dopant insulating rare earth oxides form an energy barrier, and the Gd_2O_3 :Eu^(3+) elevated the energy level of the oxide film and increased the photovoltage. The photoelectric conversion efficiency for a DSSC with Gd_2O_3 :Eu^(3+) doping (6 : 100) reached 7.01%, which was 17.4% higher than the photoelectrical conversion efficiency of a DSSC without Gd 2 O 3 :Eu 3+ doping.
LI QingBei LIN JianMing WU JiHuai LAN Zhang WANG JiangLi WANG Yue PENG FuGuo HUANG MiaoLiang XIAO YaoMing
