煤基石墨烯/TiO_2复合材料的制备及光催化性能

Preparation of coal-based graphene/TiO_2 composites and their photocatalytic activity

以资源丰富的褐煤为原料,经高温石墨化处理后,采用改进的Hummers法制备氧化石墨烯(GO),再以四氯化钛(TiCl_4)为钛源,通过水热合成法制备煤基石墨烯/TiO_2(CRGO/TiO_2)复合材料。利用扫描电镜(SEM)、能谱仪(EDS)、透射电镜(TEM)、X射线衍射仪(XRD)、低温氮气物理吸附仪、傅里叶红外光谱仪(FTIR)对复合材料的微观结构进行系统表征,并重点研究不同GO添加量下所制CRGO/TiO_2复合材料对液相中罗丹明B的光催化降解性能。结果表明:以褐煤为碳质前体,TiCl_4为钛源,采用水热合成法可合成具有介孔特征的煤基石墨烯/TiO_2复合材料,其比表面积可达88.53~169.64m^2/g,孔径主要分布在2~12nm,且随着GO添加量的增加,复合材料的孔径分布逐渐变窄。复合材料中的TiO_2纳米颗粒主要以锐钛矿晶型均匀分散于层状石墨烯表面。GO添加量是影响复合材料光催化降解性能的重要因素。当GO添加量为8%时,CRGO/TiO_2复合材料在可见光下对罗丹明B的降解率可达98.9%。

Graphene oxide(GO)was prepared from high temperature graphited lignite by modifiedHummers method.The coal-based graphene/TiO2composites were synthesized subsequently viahydrothermal method using four titanium chloride(TiCl4)as titanium source and graphene oxide ascarbon source.The microstructure of the CRGO/TiO2composites was characterized by scanningelectron microscopy(SEM),energy dispersive spectrometer(EDS),transmission electron microscope(TEM),X-ray diffraction(XRD),low temperature nitrogen adsorption and fourier transform infraredspectrometer(FTIR).The rhodamine B(RhB)photocatalytic degradation performance in liquid phaseof CRGO/TiO2prepared at different additive amount of GO were also systematically investigated.Theresults show that coal-based graphene/TiO2composites with mesoporous characteristics can be synthesized via hydrothermal method using lignite as carbonaceous precursor and TiCl4as titanium source.Thespecific surface areas of CRGO/TiO2composites are as high as88.53～169.64m2/g and the pore size ismainly in the range of2～12nm.Moreover,the pore size distribution of CRGO/TiO2compositesbecomes more narrow with the increase of GO.The TiO2particles mainly in anatase phasehomogeneously distribute on the surface or layers of graphene.The additive amount of GO is animportant factor affecting the photocatalytic degradation performance of composites,and the removalrate of CRGO/TiO2for RhB can reach98.9%under visible light irradiation when the amount of GO is8%.