CdS纳米棒/酞菁氧钛复合光导体的光电导性能

采用以溶剂热方法合成的CdS纳米棒与酞菁氧钛复合制备的复合光导体,在570nm光照下其光电导性能明显提高,将质量分数为5%的CdS纳米棒与TiOPc复合使光敏性能提高32%.电子结构的数据和表面光电压谱分析结果表明,复合体系中存在从CdS纳米棒到TiOPc的光致空穴转移,TiOPc因被CdS纳米棒敏化而表现出高的光电导性能.

Effects of Variation of Elemental Compositions of Cesium Salts of Keggin Type Heteropolyacids on Selectively Catalytic Oxidation Performance of Propane

The selective catalytic oxidation behavior of propane over the cesium salts of heteropoly acids with different elemental compositions were systematically studied. Special attentions were paid to the series of H_3+n-xCs_xPMo_12-nV_nO_40 catalysts(n=0_4, x=0_3) as well as the H_0.5Cs_2.5PW_12O_40, H_1.5Cs_2.5PW_11VO_40 and H_1.5Cs_2.5SiMo_12O_40 catalysts. The catalysts were characterized by means of BET, UV-Vis diffuse reflectance spectroscopy, FTIR, XRD, TPR and SEM to understand their physico-chemical properties. The substitution of Mo~6+ with V~5+ increased the acidity and oxidation ability of the HPAs of H_3+nPMo_12-nV_nO_40(n=0_4) samples. Substitution of proton with Cs~+ not only modified the surface acidity, but also affected the redox property as well as the structural stability of the samples, therefore, had a substantial impact on the catalytic performance for the series of H_3+n-xCs_xPMo_12-nV_nO_40(n=0_4, x=0_3) catalysts. It was found that the structural stability of HPCs increased steadily with increasing the number of cesium cation up to 3. The optimal number of cesium substitution varied along with the number of vanadium atoms existing in the primary structure of heteropoly anions. The appropriate elemental composition of heteropoly anions was found to be the key factor determining the overall catalytic behavior of the Keggin type heteropoly compounds, and the best results was {achieved} over the H_1.5Cs_2.5PMo_11VO_40 catalyst. The reaction data collected on various HPCs in this study suggest that the composition of structural atoms of heteropoly anions and the number of balanced cations are closely related to acidity, redox property and catalytic performance of HPCs, and these data also accord well with the theoretical predictions.