钛基石墨烯复合材料的制备及其光催化还原Cr（VI）的研究

通过改进的Hummers法制备氧化石墨烯(GO),再将氧化石墨烯和钛酸四丁酯作为初始反应物,利用溶剂热法制备Ti O_2/RGO纳米复合材料.利用SEM、TEM、XPS、XRD等分析手段对Ti O_2/RGO纳米复合材料进行表征,考察其在可见光照射条件下光催化还原水中Cr(Ⅵ)的效能,并对光催化还原机制进行了初步探讨.结果表明,Ti O_2/RGO复合材料的光催化还原能力与单一Ti O_2(P25)相比有了显著提高;复合材料中RGO含量、溶液p H值、催化剂投加量、Cr(Ⅵ)初始浓度均对光催化还原过程有所影响,当复合材料中RGO含量比例为2%、溶液p H值为2,催化剂投加量为40 mg时,光催化还原Cr(Ⅵ)的效率可达98%.光催化还原Cr(Ⅵ)的过程是吸附过程和光催化还原过程的共同作用结果,RGO不但提高了复合材料的吸附能力,还作为复合材料的电子导体,抑制了光生电子-空穴对的复合,增强了复合材料的光催化性能.经过5次循环使用后,复合材料的光催化还原效率仍然保持在90%左右.

Preparation of Titanium based graphene composites and their photo-catalytic reduction of Cr (VI)

The grapheme oxide (GO) was synthesized with the modified Hummers method, and the TiO₂/RGO nanocomposites were prepared through solvothermal method using GO and tetrabutyl titanate as precursors. These composites were characterized by using SEM, TEM, XPS and XRD, and their capability of photocatalytic reduction of Cr(VI) irradiated under simulated visible light was investigated. In addition, the mechanism of photocatalytic reduction was also discussed. The results indicate that the photocatalytic reduction capability of TiO₂/RGO nanocomposites was significantly higher than that of P25. The photocatalytic reduction capability was influenced by the loading ratio of RGO, pH, amount of catalyst and initial concentration of Cr(VI). Under the RGO content of 2%, pH 2, and 40 mg of catalyst, the efficiency of photocatalytic reduction reached 98%. This high photocatalytic reduction of Cr (VI) was resulted from the synergistic effect of adsorption and reduction. Not only the adsorption capacity of the composite material was improved, but also electron-hole pair recombination as the electronic conductor was inhibited and the photocatalytic properties was enhanced by the addition of RGO. After recycling 5 cycles, photocatalytic reduction efficiency of the composites still remained at around 90%.