SnO_2量子点/石墨烯复合结构的合成及其光催化性能研究

Synthesis of SnO_2 quantum dots/graphene composite and its photocatalytic performance

本文以SnCl4·5H2O和氧化石墨烯为先驱物,乙醇水溶液为溶剂,采用一种简单的水热法一步合成了具有可见光催化活性的SnO2量子点(约3—5 nm)与石墨烯复合结构,利用透射电子显微镜(TEM),高分辨透射电子显微镜(HRTEM),X射线衍射仪(XRD),傅里叶变换红外光谱(FT-IR)等技术对其结构进行了表征,利用紫外可见吸收光谱(UV-vis)分析了其光学性能,罗丹明-B染料为目标降解物研究了SnO2量子点/石墨烯复合结构可见光催化性能.结果表明:与纯SnO2、纯石墨烯相比,复合结构显示出了很高的可见光催化活性.通过对其结构进行分析,我们提出了SnO2量子点/石墨烯复合结构的形成机制及其可见光催化活性机理.

With SnCl4·5H2O and graphene oxide as raw materials and aqueous solution of ethanol as the solvent, we have prepared SnO2 quantum dots（diameter about 3–5 nm）/graphene nanocomposites using a facile hydrothermal method in one step, and solved the reunion of quantum dots successfully. The visible-light-driven photocatalytic efficiency of SnO2 quantum dots depends to a great extent on their dispersity. Because of the large-sized two-dimensional surface,the graphene sheet could behave as a solid support for quantum dots through interfacial interaction to avoid particle aggregation. Composites of SnO2 quantum dot/graphene show a great photocatalytic performance in visible light, and the morphology and structure of the product are characterized by X-ray powder diffraction（XRD）, transmission electron microscopy（TEM）, high-resolution transmission electron microscopy（HRTEM）, Fourier transform infrared Spectrometer（FT-IR） and other techniques. The optical properties are investigated by using UV-visible（UV-vis） absorption spectrum.Additionally, the photocatalytic activity of the product is measured by the degradation of rhodamine-B dye solution in visible light. Results show that the preparation of samples with high catalytic activity in visible light, the shift in the optical response of composites may produce a positive effect on the improvement of photocatalytic efficiency in UV to visible spectral range Moreover, owing to its special π-conjugation structure, large specific surface area as well as high conductivity, graphene can enhance the photocatalytic activity. Compared with the pure SnO2, pure graphene catalytic performance is greatly improved in visible light, its excellent photocatalytic activity is due to the combination of strong absorption and effective separation of photogenerated carriers in the samples. Finally, the formation mechanism of the composite and its photocatalytic mechanism are studied.