功能材料rGO/TiO₂复合光催化剂的合成与研究

Preparation and Study on Composite Photocatalysts of rGO/TiO₂ Function Materials

摘要: 本文设计采用碱性一步水热法低温下控制合成了不同石墨烯含量的rGO/TiO₂复合材料(石墨烯质量分数为0%，1%，5%，10%，15%)。通过XRD，SEM，Raman，Nitrogen adsorption-desorption等表征手段和光催化降解亚甲基蓝溶液(MB)测试，研究了石墨烯及其含量对TiO₂结构、形貌以及光催化活性的影响。结果表明：(1)强碱水热反应中GO被还原为薄片状石墨烯，用于修饰TiO₂不改变其晶相结构；适量的石墨烯掺杂使复合物的粒径减小，比表面积增大，电子扩散、迁移阻抗减小。(2)适量的石墨烯不仅可增强污染物与光催化剂的有效接触，还可作为电子受体促进TiO₂电子-空穴的分离，使TiO₂的光催化活性提高。(3)但过量的石墨烯不光会覆盖TiO₂的部分活性位点，还易于参与形成团聚产物，不利于TiO₂光催化活性的提高。因此，当石墨烯含量为5%时，rGO/TiO₂对MB的光催化活性提高到86.3%，光催化性能最佳。这为碳材料改性TiO₂光催化剂的绿色开发提供了一种可靠途径。

Abstract: In this paper, rGO/TiO₂ composites with different amount of graphene were controllably synthesized by alkaline one-step hydrothermal method (the content of graphene is 0%, 1%, 5%, 10% and 15%). By XRD, SEM, Raman, Nitrogen adsorption-desorption and photocatalytic degradation of methylene blue solution (MB), we explored the effect of graphene and its contents on optimizing TiO₂ structure, morphology and photocatalytic activity. The results indicated that: (1) GO was reduced to thin-flake graphene in the strong alkaline hydrothermal reaction. Besides, the doping of graphene did not change the crystalline phase structure of TiO₂, but resulted in the decrease of particle size and increase of surface area when it comes to composites. Secondly, it also reduced the diffusion and transfer impedance of electrons. (2) Appropriate amount of graphene not only enhanced the effective contact between pollutants and photocatalysts, but also can be used as electron acceptor to promote the separation of electron-hole of TiO₂, thus improving the photocatalytic activity of TiO₂. (3) But excessive graphene would be able to covered partial ac-tive-sites of TiO₂ and participated in the formation of agglomeration products, which was not conducive to the improvement of TiO₂ photocatalytic activity. Therefore, rGO/TiO₂ with 5% gra-phene revealed the best photocatalytic performance, and its photocatalytic activity to MB solution increased to 86.3%. This provides a reliable way for the ecological development of Carbon materials modified TiO₂ photocatalyst.