The Study Of Properties And Applications Of Ternary Hydrotalcite-like Compounds And Their Composite Oxides

Series of ZnAl、ZnAlLa and ZnCdAl hydrotalcite-like compounds (HTlc) were prepared by urea method and their composite oxides were obtained after calcined at 500℃. The structure, morphology, energy band, surface properties of HTlc and composite oxides were characterized by XRD, TG-DTA, SEM, N2 adsorption, UV-vis and FT-IR. Composite oxides were used as photoanode materials, and then the application in DSSC was studied systematically. The photocatalytic activity of ZnAlLa and ZnCdAl composite oxides was tested using methyl orange (MO) and Rhodamine B (RhB) as the model reaction. The research results show that:(1) The ZnAl-HT1c with different molar ratio (Zn:Al= 2,4,6,8) were prepared by urea method and composite oxides were prepared by calcining the HTlc at 500℃. Results showed that the crystallinity of samples was relatively good, the compactness of particles decreased with the molar ratio increase, and band gaps of composites were narrower than ZnO.(2) ZnAlLa and ZnCdAl HT1c with different comcentration of La3+ and Cd2+ were prepared. Rseults showed that the influence of La3+ and Cd2+ on the structure and morphology was little. The analysis results indicated that La3+ and Cd2+ had entered into hydrotalcite structure.(3) DSSC were prepared by assembling using ZnAl composite oxides as photoanode, N719, N3, D205 as sensitizer respectively, then comprehensive performance of DSSC were studied systematically. I-V test, stability test and electrochemical impedance spectroscopy test were used. Results showed that the performances of the D205 system DSSC were much well than others. The efficiency of DSSC rose with the increase of ZnAl molar ratio under the same dye system. The stability of the cells is good, and that relatively high efficiency can maintain a long time; EIS test results explain the performance of DSSC in terms of internal resistance.(4) DSSC were prepared by assembling using ZnAlLa and ZnCdAl composite oxides as photoanode, N3 and D205 as sensitizer respectively, then comprehensive performance of DSSC were studied systematically. Ⅰ-Ⅴ test, stability test and electrochemical impedance spectroscopy were used. Results showed that the performances of the D205 system DSSC were much well tthan others. The stability of the cells is good. The efficiency firstly increased and then decreased which consistent with results of N2 adsorption. EIS test results explain the performance of DSSC in terms of internal resistance.(5) The methyl orange and rhodamine B photocatalytic experiments were carried out using ZnAlLa composite oxides as photocatalyst. Results showed that the heterojunction formed by La2O3 and ZnO had the very good photocatalytic ability. The photocatalytic efficiency firstly increased and then decreased with La3+ concentration increasing. The photocatalytic result was analyzed by the energy band and the charge transfer, the properties of La3+and adsorption capacity of composite oxides.(6) The methyl orange and rhodamine B photocatalytic experiments were carried out using ZnCdA1 composite oxides as photocatalyst. Results showed that the heterojunction formed by ZnO and CdO had the very good photocatalytic ability. The photocatalytic efficiency firstly increased and then decreased with Cd2+ concentration increasing. The photocatalytic result was analyzed by the energy band and the charge transfer of composite oxides.