Xu Jimeng, Sang Huanxin, Wang Xitao, Wang Kang
Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
Dalton Trans. 2015 May 28;44(20):9528-37. doi: 10.1039/c5dt00293a.
In the present study, ZnS-CdS solid solution sensitized ZnO nanorods were anchored on graphene sheets by combining a hydrothermal process and ion exchange technique, and the significant influence of CdS content in the shell on photo absorption and photocatalytic performance were investigated. Electron microscopic images reveal that the as-prepared nanocomposites display a sandwich-like 3D structure, consisting of ZnO nanorods with a ZnxCd1-xS or CdS shell grown vertically on both sides of the graphene sheets. UV/Vis DRS shows that the solid solution sensitized nanocomposites have enhanced visible light absorption and also exhibited a red-shift of the band-edge as compared to RGO/ZnO and RGO/ZnO@ZnS. Fluorescence emission spectra indicate that the deposition of CdS on the shell with an appropriate CdS/ZnS ratio and the incorporation of graphene causes improved charge separation. The photocatalytic experiments demonstrate that the RGO/ZnO@ZnxCd1-xS nanocomposites possess much higher photocatalytic activity for H2 evolution than the RGO/ZnO nanorods and RGO/ZnO@ZnS core/shell nanorods. Under the irradiation of a 300 W Xe lamp, the highest photocatalytic hydrogen production rate of 1865 μmol h(-1) g(-1) is observed over the RGO/ZnO@Zn0.6Zn0.4S sample, which is about 2.1 and 1.4 times more active than RGO/ZnO and RGO/ZnO@ZnS, respectively. Under the irradiation of visible light (>420 nm), the RGO/ZnO and RGO/ZnO@ZnS nanorods are barely active, whereas RGO/ZnO@Zn0.6Zn0.4S displays a hydrogen production rate of 160 μmol h(-1) g(-1). The highly improved performance of the composites can be ascribed to the increased light absorption and efficient charge separation.
在本研究中，通过水热法和离子交换技术相结合，将ZnS - CdS固溶体敏化的ZnO纳米棒锚定在石墨烯片上，并研究了壳层中CdS含量对光吸收和光催化性能的显著影响。电子显微镜图像显示，所制备的纳米复合材料呈现出三明治状的三维结构，由在石墨烯片两侧垂直生长的具有ZnxCd1 - xS或CdS壳层的ZnO纳米棒组成。紫外/可见漫反射光谱表明，固溶体敏化的纳米复合材料增强了可见光吸收，并且与RGO/ZnO和RGO/ZnO@ZnS相比，其带边也出现了红移。荧光发射光谱表明，以适当的CdS/ZnS比例在壳层上沉积CdS以及引入石墨烯可改善电荷分离。光催化实验表明，RGO/ZnO@ZnxCd1 - xS纳米复合材料对H2析出的光催化活性远高于RGO/ZnO纳米棒和RGO/ZnO@ZnS核壳纳米棒。在300 W氙灯照射下，RGO/ZnO@Zn0.6Zn0.4S样品的最高光催化产氢速率为1865 μmol h(-1) g(-1)，分别比RGO/ZnO和RGO/ZnO@ZnS活性高约2.1倍和1.4倍。在可见光（>420 nm）照射下，RGO/ZnO和RGO/ZnO@ZnS纳米棒几乎没有活性，而RGO/ZnO@Zn0.6Zn0.4S的产氢速率为160 μmol h(-1) g(-1)。复合材料性能的高度提升可归因于光吸收的增加和有效的电荷分离。
