Synthesis and Photo-chemical Properites of Semiconductors Incorporated in the Interlayer

制备了层间掺杂半导体纳米粒子的层状化合物/半导体纳米复合材料，并研究了其光化学性质。半导体如CdS、Fe_2O_3。CuO、NiO、MnO、TiO_2等依次嵌入到H_2Ti_4O_9、H_4Nb_6O_6、<17>HCaNb_3O_6<10>、HNbWO_6、HTaWO_6等层状化合物中，嵌入的半导体颗粒厚度小于1 nm，带隙能量略大于普通无支撑半导体晶体。在可见光（波长&gt;400 nm）照射下，掺入CdS、Fe_2O_3、CuO、NiO和MnO等小禁带半导体的纳米复合材料具有良好的析氢活性。另一方面，TiO_2和/或TiO_2与Pt的纳米复合材料能够在不牺牲空穴受体的情况下通过带隙辐照将水转化为氢和氧。半导体纳米粒子的光催化活性主要是通过电子转移实现的电荷分离。通过分析CdS和TiO_2在H_2T_O_9和H_4Nb_6O_2中的荧光寿命<14>，<17>证实了中间层中CdS和/或TiO_2中的光生电子迅速转移到基质层。测得CdS与H_2Ti_4O_9和/或H_4Nb_6O_3之间的电子转移速率常数<17>为ca。从TiO_2到H_2T_O_9和H_4Nb_6O_3的反应速率<14><17>为108 sec ~（-1）<-1>。

Layered compound/semiconductor nonocomposites incorporating semiconductor nanoparticles in the interlayer of layered compounds were fabricated and their photo-chemical properties were investigate. Semiconductors such as CdS, Fe_2O_3. CuO, NiO, MnO, TiO_2, etc. were successively intercalated in various layered compounds such as H_2Ti_4O_9, H_4Nb_6O_<17>, HCaNb_3O_<10>, HNbWO_6, HTaWO_6, etc. The thickness of semiconductor particles incorporated was less than 1 nm and the band gap energy was slightly larger than that of normal unsupported semiconductor crystals. Nonocomposites incorporating small band gap semiconductor such as CdS, Fe_2O_3, CuO, NiO and MnO showed efficient hydrogen evolution activity under visible light irradiation (wave length>400 am). On the other hand, nanocomposites incorporating TiO_2 and/or TiO_2 and Pt were capable to clevage water into hydrogen and oxygen without sacrificial hole acceptor by band gap irradiation. The excellent photocatalytic activity of semiconductor particles incorporated wad attributed to the charge separation by guest to host electron transfer. By analyzing the fluorescence life times of CdS and TiO_2 incorporated in H_2T_<14>O_9 and H4Nb_6O_<17>, it was confirmed that photoinduced electron in CdS and/or TiO_2 in the interlayer quickly transfer to the host layers. The electron transfer rate constant from CdS to H2Ti4O9 and/or H_4Nb_6O_<17> were determined as ca. 10^6 sec-1 and those from TiO_2 to H_2T_<14>O_9 and H_4Nb_6O_<17> were l08 sec^<-1>.