Direct Nanocoupling between Sulfide- and Oxide-Semiconductors by a Photodeposition Technique

利用TiO_2的光诱导性质、表面的亲水性和可降解性，发展了一种简单而通用的光沉积技术，用于纳米尺度上金属硫化物量子点与TiO_2的偶联。金属硫化物-TiO_2耦合体系具有以下特点：（I）在相当短的时间内可以在TiO_2上直接形成大量的金属硫化物，并且具有良好的再现性。（II）金属硫化物量子点的能带能量可以通过照射时间或表面改性剂浓度进行宽范围的调节，（III）金属硫化物量子点不仅可以沉积在介孔TiO_2纳米晶薄膜的外表面，而且可以沉积在介孔TiO_2纳米晶薄膜的内表面，而不会堵塞孔道，（V）该技术具有将TiO_2与窄禁带金属硫化物偶联的广泛可能性，适合于太阳能转换的应用。这些独特的功能产生了优异的性能，作为光催化剂和QD-SSC和QD-SPEC电池的光阳极，从水制氢的所得heteronanojunaction系统。

Simple and versatile photodeposition techniques taking advantage of the photoinduced properties of TiO_2, photocatalysis and surface superhydrophilicity, have been developed for coupling metal sulfide QDs and TiO_2 at a nonoscale. The coupled metal sulfide-TiO_2 systems possess the following characteristics : (I) a large amount of metal sulfides can be directly formed on TiO_2 during a fairly short period with excellent reproducibility, (II) the band energies of metal sulfides QDs are widely tunable by irradiation time or surface modifier concentration, (III) metal sulfide QDs can be deposited on not only the external surfaces but also the inner ones of mesoporous TiO_2 nanocrystalline films without pore-blocking, (IV) the simple solution-based technique at low temperature enables the low-cost production, (V) this technique has a wide possibility for coupling TiO_2 and narrow gap metal sulfides suitable for the applications to the solar energy conversion. These unique features produce the excellent performances of the resulting heteronanojunaction systems as photocatalysts and the photoanodes for QD-SSC and QD-SPEC cells for hydrogen production from water.