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

制备了层状化合物/半导体纳米复合材料，并对其光化学性质进行了研究。在层状化合物H_2Ti_4O_9、H_4Nb_6O_(17)、HCaNb_3O_(10)、HNbWO_6、HNbWO_6、HTaWO_6等层状化合物中，先后插入了半导体Cd、Fe_2O_3、CuO、NiO、MnO、TiO_2等。在可见光(波长400Am)照射下，含小禁带半导体的纳米复合材料表现出高效的析氢活性。另一方面，通过带隙辐射，纳米二氧化钛和/或二氧化钛与铂复合后，可以在没有牺牲空穴受主的情况下将水转化为氢气和氧气。所掺入的半导体粒子具有优异的光催化活性，这归功于客体到主体电子转移的电荷分离。通过对掺入H_2T_(14)和H_4Nb_6O_(17)和H_4Nb_6O_(？)测定了硫化镉与H_2Ti4O_9和/或H_4Nb_6O_(17)的电子转移速率常数约为10^6秒~(-1)，从TiO_2到H_2T_(14)O_9和H_4Nb_6O_(17)的电子转移速率常数为108秒~(-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>.