Abstract Highly porous nanocrystalline TiO2 films were sensitized with ZnS semiconductor nanocrystals by using a three-step facile strategy. The TiO2 matrices were firstly impregnated with the zinc bis(benzyl)thiol precursor that, unlike many other metal chalcogenides, is easily dispersible in the most common organic solvents. In the second step of the adopted synthetic strategy, the TiO2 impregnated with zinc thiolate was annealed at 250 °C in order to induce nucleation and growth of ZnS nanocrystals inside the porous matrices as well as on the film surface. A final cleavage in dichloromethane allowed us to remove all residual organic reagents and products. The size of the ZnS nanocrystals can be tuned by variation of the annealing time as shown by X-ray diffraction measurements, without changing the crystallographic phase structure (zincblende structure). Scanning electron microscopy analysis showed a random spatial dispersion of the ZnS nanocrystals and no remarkable aggregation was observed. The sensor device based on TiO2-ZnS nanocomposite was able to detect NO2 gas at 270 °C down to 1 ppm with negligible response towards reducing gases (CO, CH4). Compared to bare TiO2 film, the TiO2-ZnS nanocomposite shows higher sensitivity and lower recovery time towards an oxidant NO2 gas.

中文翻译：

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用于增强 NO2 气体传感的纳米晶 ZnS/TiO2 薄膜的合成

摘要 通过三步简便的策略，用 ZnS 半导体纳米晶体敏化了高度多孔的纳米 TiO2 薄膜。TiO2 基体首先用双（苄基）硫醇锌前体浸渍，与许多其他金属硫属元素化物不同，它很容易分散在最常见的有机溶剂中。在所采用的合成策略的第二步中，用硫醇锌浸渍的 TiO2 在 250°C 下退火，以诱导多孔基质内部以及薄膜表面上 ZnS 纳米晶体的成核和生长。在二氯甲烷中的最后裂解使我们能够去除所有残留的有机试剂和产物。如 X 射线衍射测量所示，可以通过改变退火时间来调整 ZnS 纳米晶体的尺寸，不改变晶相结构（锌闪石结构）。扫描电子显微镜分析显示 ZnS 纳米晶体的随机空间分散，没有观察到显着的聚集。基于 TiO2-ZnS 纳米复合材料的传感器装置能够在 270 °C 下检测低至 1 ppm 的 NO2 气体，对还原性气体（CO、CH4）的响应可以忽略不计。与裸 TiO2 薄膜相比，TiO2-ZnS 纳米复合材料对氧化性 NO2 气体显示出更高的灵敏度和更短的恢复时间。